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    Opioid Agonists and Other Drug Combinations

    BOXED WARNING

    Accidental exposure, alcoholism, depression, ethanol intoxication, hepatic disease, hepatitis, hepatotoxicity, hypovolemia, malnutrition, opioid overdose, opioid use disorder, potential for overdose or poisoning, substance abuse, suicidal ideation

    Do not prescribe tramadol; acetaminophen for patients who have suicidal ideation or are addiction-prone; consider use of non-narcotic analgesics in patients who are suicidal or depressed. Use tramadol; acetaminophen with caution in patients with a history of misuse or who are taking central nervous system active drugs, including tranquilizers or antidepressants or alcohol in excess, and patients who suffer from emotional disturbance or depression. As an opioid, tramadol exposes users to the risks of addiction, abuse, and misuse. Although the risk of addiction in any individual is unknown, it can occur in patients appropriately prescribed tramadol. Addiction can occur at recommended dosages and if the drug is misused or abused. Assess each patient's risk for opioid addiction, abuse, or misuse before prescribing tramadol; acetaminophen, and monitor all patients receiving tramadol; acetaminophen for the development of these behaviors or conditions. Risks are increased in patients with a personal or family history of substance abuse (including alcoholism) or mental illness (e.g., major depression). The potential for these risks should not prevent the proper management of pain in any given patient. Patients at increased risk may be prescribed opioids such as tramadol, but use in such patients necessitates intensive counseling about the risks and proper use of tramadol along with intensive monitoring for signs of addiction, abuse, and misuse. Tramadol; acetaminophen should be kept out of the reach of pediatric patients, others for whom the drug was not prescribed, and pets as accidental exposure or improper use may cause respiratory failure and a fatal overdose. Abuse and addiction are separate and distinct from physical dependence and tolerance; patients with addiction may not exhibit tolerance and symptoms of physical dependence. Opioids are sought by drug abusers and people with addiction disorders and are subject to criminal diversion. Abuse of tramadol; acetaminophen has the potential for overdose or poisoning and death. Consider these risks when prescribing or dispensing tramadol; acetaminophen. Strategies to reduce these risks include prescribing the drug in the smallest appropriate quantity. Discuss the availability of naloxone with all patients and consider prescribing it in patients who are at increased risk of opioid overdose, such as patients who are also using other CNS depressants, who have a history of opioid use disorder (OUD), who have experienced a previous opioid overdose, or who have household members or other close contacts at risk for accidental exposure or opioid overdose. Accidental exposure of even a single dose of tramadol, especially by younger persons, can result in a fatal overdose of tramadol. Tramadol; acetaminophen use is not recommended in patients with hepatic disease. Tramadol exposure was higher and half-lives of tramadol and metabolite M1 were longer in patients with advanced cirrhosis of the liver than in subjects with normal hepatic function. Acetaminophen has the potential for overdose or poisoning causing hepatotoxicity and acute liver failure, at times resulting in liver transplantation and death. Most cases of liver injury are associated with the use of acetaminophen at doses exceeding 4 g/day and often involve the use of more than 1 acetaminophen-containing product. Use caution during the measurement of oral liquid dosage forms to minimize the risk of dosing errors that can result in accidental overdose. Advise patients receiving acetaminophen to carefully read OTC and prescription labels, to avoid excessive and/or duplicate medications, and to seek medical help immediately if more than 4 g/day of acetaminophen is ingested, even if they feel well. It is important to note that the risk of acetaminophen-induced hepatotoxicity is increased in patients with pre-existing hepatic disease (e.g., hepatitis), those who ingest alcohol (e.g., ethanol intoxication, alcoholism), those with chronic malnutrition, and those with severe hypovolemia. In patients with chronic hepatic disease, acetaminophen can be used safely in recommended doses and is often preferred to nonsteroidal anti-inflammatory drugs (NSAIDs) due to the absence of platelet impairment, gastrointestinal toxicity, and nephrotoxicity. Though the half-life of acetaminophen may be prolonged, repeated dosing does not result in drug or metabolite accumulation. In addition, cytochrome P450 activity is not increased and glutathione stores are not depleted in hepatically impaired patients taking therapeutic doses, therefore toxic metabolite formation and accumulation is not altered. Although it is always prudent to use the smallest dose of acetaminophen for the shortest duration necessary, courses less than 2 weeks in length have been administered safely to adult patients with stable chronic liver disease.

    Asthma, chronic obstructive pulmonary disease (COPD), coadministration with other CNS depressants, cor pulmonale, hypoxemia, respiratory depression, respiratory insufficiency, sleep apnea

    Tramadol; acetaminophen is contraindicated in patients with significant respiratory depression and those with acute or severe asthma in an unmonitored setting or in the absence of resuscitative equipment. Avoid coadministration with other CNS depressants when possible, as this significantly increases the risk for profound sedation, respiratory depression, coma, and death. Reserve concomitant prescribing of these drugs for use in patients for whom alternative treatment options are inadequate; if concurrent use is necessary, use the lowest effective dosages and minimum treatment durations needed. Monitor patients closely for signs or symptoms of respiratory depression and sedation. [61143] Patients with chronic obstructive pulmonary disease (COPD), cor pulmonale, respiratory insufficiency, hypoxemia, hypercapnia, or preexisting respiratory depression are at increased risk of decreased respiratory drive even at recommended doses. Patients with advanced age, cachexia, or debilitation are also at an increased risk for opioid-induced respiratory depression. Monitor such patients closely, particularly when initiating and titrating the opioid; consider the use of non-opioid analgesics in these patients. Opioids increase the risk of central sleep apnea (CSA) and sleep-related hypoxemia in a dose-dependent fashion. Consider decreasing the opioid dosage in patients with CSA. Respiratory depression, if left untreated, may cause respiratory arrest and death. Carbon dioxide retention from respiratory depression may also worsen opioid sedating effects. Careful monitoring and dose titration is required, particularly when CYP3A4 inhibitors or inducers and/or CYP2D6 inhibitors are used concomitantly. The effects of concomitant use or discontinuation of CYP3A4 inhibitors or inducers or CYP2D6 inhibitors on concentrations of tramadol and its active metabolite, M1, are complex and may potentiate the risk of fatal respiratory depression or result in opioid withdrawal and reduced efficacy. Management of respiratory depression may include observation, necessary supportive measures, and opioid antagonist use when indicated.

    Adenoidectomy, children, infants, neonates, neuromuscular disease, obesity, pulmonary disease, respiratory infection, tonsillectomy

    Tramadol; acetaminophen is contraindicated in neonates, infants, and children younger than 12 years and for postoperative pain management in pediatric patients younger than 18 years after a tonsillectomy and/or adenoidectomy. Avoid use in patients 12 to 18 years of age who have other risk factors for respiratory depression unless the benefits outweigh the risks. Risk factors include conditions associated with hypoventilation such as postoperative status, obstructive sleep apnea, obesity, respiratory infection, asthma, severe pulmonary disease, neuromuscular disease, and concomitant use of other respiratory depressants. When prescribing codeine for adolescents, choose the lowest effective dose for the shortest period of time and inform patients and caregivers of the risks and the signs of opioid overdose. Ultrarapid metabolizers of CYP2D6 substrates may convert tramadol to its active metabolite, O-desmethyltramadol, more quickly and completely than usual, leading to higher than normal opioid blood concentrations that can result in fatal respiratory failure. Because some children who are normal metabolizers can covert opioids at similar rates to ultrarapid metabolizers, this concern extends to all pediatric patients.

    Labor, neonatal opioid withdrawal syndrome, obstetric delivery, pregnancy

    Data are insufficient to inform a drug-associated risk for major birth defects or miscarriage with tramadol; acetaminophen use in human pregnancy. Tramadol and acetaminophen cross the placenta. Based on animal data, tramadol; acetaminophen may cause fetal harm; advise pregnant women of the potential risk to the fetus. In animal studies of tramadol, decreased fetal weights and reduced ossification were observed in mice, rats, and rabbits at 1.4, 0.6, and 3.6 times the maximum recommended human daily dosage (MRHD). Decreased body weight and increased mortality were observed in pups at tramadol doses of 1.2 and 1.9 times the MRHD. Tramadol; acetaminophen is not recommended for use during and immediately before labor when other analgesic techniques are more appropriate. Opioids can prolong labor and obstetric delivery by temporarily reducing the strength, duration, and frequency of uterine contractions. This effect is not consistent and may be offset by an increased rate of cervical dilatation, which may shorten labor. Opioids cross the placenta and may produce respiratory depression and psycho-physiologic effects in the neonate. Monitor neonates exposed to opioid analgesics during labor for signs of excess sedation and respiratory depression. An opioid antagonist (e.g., naloxone) should be available for reversal of opioid-induced respiratory depression in the neonate. The mean ratio of serum tramadol in the umbilical veins compared to maternal veins was 0.83 for 40 women treated with tramadol during labor. Further, prolonged maternal use of opioids during pregnancy may result in neonatal opioid withdrawal syndrome (NOWS). Monitor the exposed neonate for withdrawal symptoms, including irritability, hyperactivity and abnormal sleep pattern, high-pitched cry, tremor, vomiting, diarrhea, and failure to gain weight, and manage accordingly. Onset, duration, and severity of opioid withdrawal may vary based on the specific opioid used, duration of use, timing and amount of last maternal use, and rate of elimination by the newborn. [55881] Guidelines recommend early universal screening of pregnant patients for opioid use and opioid use disorder at the first prenatal visit. Obtain a thorough history of substance use and review the Prescription Drug Monitoring Program to determine if patients have received prior prescriptions for opioids or other high-risk drugs such as benzodiazepines. Discuss the risks and benefits of opioid use during pregnancy, including the risk of becoming physiologically dependent on opioids, the possibility for NOWS, and how long-term opioid use may affect care during a future pregnancy.[64838] [64909] In women undergoing uncomplicated normal spontaneous vaginal birth, consider opioid therapy only if expected benefits for both pain and function are anticipated to outweigh risks to the patient. If opioids are used, use in combination with nonpharmacologic therapy and nonopioid pharmacologic therapy, as appropriate. Use immediate-release opioids instead of extended-release or long-acting opioids; order the lowest effective dosage and prescribe no greater quantity of opioids than needed for the expected duration of such pain severe enough to require opioids.[64909] For women using opioids for chronic pain, consider strategies to avoid or minimize the use of opioids, including alternative pain therapies (i.e., nonpharmacologic) and nonopioid pharmacologic treatments. Opioid agonist pharmacotherapy (e.g., methadone or buprenorphine) is preferable to medically supervised withdrawal in pregnant women with opioid use disorder.[64838] Published epidemiological studies have not reported a clear association with acetaminophen use during pregnancy and birth defects, miscarriage, or adverse maternal or fetal outcomes. Large observational studies of newborns exposed to oral acetaminophen during the first trimester have not shown an increased risk for congenital malformations or major birth defects; however, these studies cannot definitely establish the absence of risk because of methodological limitations. Acetaminophen does cross the placenta and should be used during pregnancy only if the benefits to the mother outweigh the potential risks to the fetus or infant. No overall increase in fetal mortality, determined by pregnancy outcomes of mothers that overdosed on various amounts of oral acetaminophen, was apparent amongst 300 women. Treatment with acetylcysteine or methionine did not appear to affect fetal or neonatal toxicity. Of 235 infants exposed to an overdose of only acetaminophen, 168 were normal, 8 had malformations, 16 were spontaneously aborted, and 43 were electively terminated. None of the infants with malformations were exposed during the first trimester, but all of the spontaneous abortions were subsequent to first trimester exposure.

    DEA CLASS

    Rx, schedule IV

    DESCRIPTION

    Oral combination of an opioid analgesic and a non-opioid, non-salicylate analgesic
    Used for the treatment of acute pain, severe enough to require an opioid analgesic and for which alternative treatments are inadequate
    Tramadol is associated with risk for seizures and suicidal tendency; acetaminophen doses above the maximum recommended are associated with hepatotoxicity

    COMMON BRAND NAMES

    Ultracet

    HOW SUPPLIED

    Tramadol Hydrochloride, Acetaminophen/Tramadol, Acetaminophen/Ultracet Oral Tab: 37.5-325mg

    DOSAGE & INDICATIONS

    For the treatment of acute severe pain requiring an opioid analgesic and for which alternative treatments are inadequate.
    Oral dosage (tablets containing tramadol 37.5 mg and acetaminophen 325 mg)
    Adults

    2 tablets PO every 4 to 6 hours as needed. Max: 8 tablets/day. Tramadol; acetaminophen is not FDA-approved for use for more than 5 days.

    For the treatment of diabetic neuropathy†.
    Oral dosage (tablets containing tramadol 37.5 mg and acetaminophen 325 mg)
    Adults

    1 tablet PO at bedtime as needed on days 1 to 3, followed by 1 tablet PO twice daily as needed on days 4 to 6, followed by 1 tablet PO 3 times daily as needed on days 7 to 9, then by 1 tablet PO 4 times daily as needed on day 10, and thereafter, 1 to 2 tablets PO 4 times daily as needed. Max: 8 tablets/day. Guidelines consider tramadol;acetaminophen probably effective in lessening the pain of diabetic neuropathy.

    †Indicates off-label use

    MAXIMUM DOSAGE

    Adults

    300 mg/day PO tramadol and 2,600 mg/day PO acetaminophen.

    Geriatric

    300 mg/day PO tramadol and 2,600 mg/day PO acetaminophen.

    Adolescents

    Safety and efficacy have not been established.

    Children

    12 years: Safety and efficacy have not been established.
    1 to 11 years: Use is contraindicated.

    Infants

    Use is contraindicated.

    DOSING CONSIDERATIONS

    Hepatic Impairment

    Use in patients with hepatic impairment is not recommended.

    Renal Impairment

    CrCl 30 mL/minute or more: No dosage adjustment needed.
    CrCl less than 30 mL/minute: Do not exceed 2 tablets PO every 12 hours.

    ADMINISTRATION

    For storage information, see specific product information within the How Supplied section.

    Oral Administration

    May administer with or without food.
    Storage: Keep tramadol; acetaminophen secured in a location not accessible by others.
    Disposal: Mix (do not crush) unused medication with an unpalatable substance such as dirt, cat litter, or unused coffee grounds, place in a sealed container, and throw the container in the household trash when it is no longer needed if a drug take-back option is not readily available.

    STORAGE

    Generic:
    - Store at controlled room temperature (between 68 and 77 degrees F)
    Ultracet:
    - Store at controlled room temperature (between 68 and 77 degrees F)

    CONTRAINDICATIONS / PRECAUTIONS

    Acetaminophen hypersensitivity, opiate agonist hypersensitivity

    Tramadol; acetaminophen is contraindicated in patients with known acetaminophen hypersensitivity, tramadol hypersensitivity, opiate agonist hypersensitivity, or hypersensitivity to any other component of the product. Serious and rarely fatal anaphylactic reactions have been reported in patients receiving tramadol, often after the first dose. Patients with a history of hypersensitivity reactions to tramadol and other opioids may be at increased risk and therefore should not receive tramadol. If anaphylaxis or other hypersensitivity occurs, discontinue tramadol and do not rechallenge with any formulation of tramadol. Advise patients to seek immediate medical attention if they experience any symptoms of a hypersensitivity reaction. Acetaminophen hypersensitivity reactions are rare, but severe sensitivity reactions are possible. Patients who have experienced a serious skin reaction with acetaminophen should not take the drug again; discuss alternative pain relievers/fever reducers with these patients and/or their caregivers.

    Accidental exposure, alcoholism, depression, ethanol intoxication, hepatic disease, hepatitis, hepatotoxicity, hypovolemia, malnutrition, opioid overdose, opioid use disorder, potential for overdose or poisoning, substance abuse, suicidal ideation

    Do not prescribe tramadol; acetaminophen for patients who have suicidal ideation or are addiction-prone; consider use of non-narcotic analgesics in patients who are suicidal or depressed. Use tramadol; acetaminophen with caution in patients with a history of misuse or who are taking central nervous system active drugs, including tranquilizers or antidepressants or alcohol in excess, and patients who suffer from emotional disturbance or depression. As an opioid, tramadol exposes users to the risks of addiction, abuse, and misuse. Although the risk of addiction in any individual is unknown, it can occur in patients appropriately prescribed tramadol. Addiction can occur at recommended dosages and if the drug is misused or abused. Assess each patient's risk for opioid addiction, abuse, or misuse before prescribing tramadol; acetaminophen, and monitor all patients receiving tramadol; acetaminophen for the development of these behaviors or conditions. Risks are increased in patients with a personal or family history of substance abuse (including alcoholism) or mental illness (e.g., major depression). The potential for these risks should not prevent the proper management of pain in any given patient. Patients at increased risk may be prescribed opioids such as tramadol, but use in such patients necessitates intensive counseling about the risks and proper use of tramadol along with intensive monitoring for signs of addiction, abuse, and misuse. Tramadol; acetaminophen should be kept out of the reach of pediatric patients, others for whom the drug was not prescribed, and pets as accidental exposure or improper use may cause respiratory failure and a fatal overdose. Abuse and addiction are separate and distinct from physical dependence and tolerance; patients with addiction may not exhibit tolerance and symptoms of physical dependence. Opioids are sought by drug abusers and people with addiction disorders and are subject to criminal diversion. Abuse of tramadol; acetaminophen has the potential for overdose or poisoning and death. Consider these risks when prescribing or dispensing tramadol; acetaminophen. Strategies to reduce these risks include prescribing the drug in the smallest appropriate quantity. Discuss the availability of naloxone with all patients and consider prescribing it in patients who are at increased risk of opioid overdose, such as patients who are also using other CNS depressants, who have a history of opioid use disorder (OUD), who have experienced a previous opioid overdose, or who have household members or other close contacts at risk for accidental exposure or opioid overdose. Accidental exposure of even a single dose of tramadol, especially by younger persons, can result in a fatal overdose of tramadol. Tramadol; acetaminophen use is not recommended in patients with hepatic disease. Tramadol exposure was higher and half-lives of tramadol and metabolite M1 were longer in patients with advanced cirrhosis of the liver than in subjects with normal hepatic function. Acetaminophen has the potential for overdose or poisoning causing hepatotoxicity and acute liver failure, at times resulting in liver transplantation and death. Most cases of liver injury are associated with the use of acetaminophen at doses exceeding 4 g/day and often involve the use of more than 1 acetaminophen-containing product. Use caution during the measurement of oral liquid dosage forms to minimize the risk of dosing errors that can result in accidental overdose. Advise patients receiving acetaminophen to carefully read OTC and prescription labels, to avoid excessive and/or duplicate medications, and to seek medical help immediately if more than 4 g/day of acetaminophen is ingested, even if they feel well. It is important to note that the risk of acetaminophen-induced hepatotoxicity is increased in patients with pre-existing hepatic disease (e.g., hepatitis), those who ingest alcohol (e.g., ethanol intoxication, alcoholism), those with chronic malnutrition, and those with severe hypovolemia. In patients with chronic hepatic disease, acetaminophen can be used safely in recommended doses and is often preferred to nonsteroidal anti-inflammatory drugs (NSAIDs) due to the absence of platelet impairment, gastrointestinal toxicity, and nephrotoxicity. Though the half-life of acetaminophen may be prolonged, repeated dosing does not result in drug or metabolite accumulation. In addition, cytochrome P450 activity is not increased and glutathione stores are not depleted in hepatically impaired patients taking therapeutic doses, therefore toxic metabolite formation and accumulation is not altered. Although it is always prudent to use the smallest dose of acetaminophen for the shortest duration necessary, courses less than 2 weeks in length have been administered safely to adult patients with stable chronic liver disease.

    Renal disease, renal failure, renal impairment

    Dosing reduction is recommended for tramadol; acetaminophen in patients with creatinine clearance less than 30 mL/minute. The excretion of tramadol and metabolite M1 is reduced in patients with renal impairment or renal failure. Some studies have suggested an association between chronic use of acetaminophen and renal effects. There is negligible evidence to suggest chronic use of acetaminophen causes analgesic nephropathy; however, there is a weak association between chronic acetaminophen use and the prevalence of chronic renal failure and end-stage renal disease.[54096] In a case-controlled study of adults with early renal failure, the regular use of acetaminophen (without aspirin) was associated with a risk of chronic renal failure that was 2.5-times higher than that for non-acetaminophen users. The risk increased with an increasing cumulative acetaminophen lifetime dose. The average dose used during periods of regular acetaminophen use also correlated with risk, as those who took at least 1.4 g/day during periods of regular use had an odds ratio for chronic renal failure of 5.3; duration of therapy was unrelated to risk.[27368] Guidelines consider acetaminophen as the non-narcotic analgesic of choice for episodic pain in patients with chronic renal disease but discourage habitual consumption.[54096]

    G6PD deficiency

    Patients with G6PD deficiency who overdose with acetaminophen may be at increased risk for drug-induced hemolysis. Practitioners should be aware of this potential complication and monitor at-risk patients for signs and symptoms of hemolysis. Conflicting data exists on whether therapeutic doses of acetaminophen can cause hemolysis in G6PD deficient patients. However, a direct cause and effect relationship has not been well established and therefore, therapeutic doses are generally considered safe in this population.

    Bone marrow suppression, immunosuppression, infection, neutropenia

    Symptoms of acute infection (e.g., fever, pain) can be masked during treatment with acetaminophen in patients with bone marrow suppression, especially neutropenia, or immunosuppression.

    Asthma, chronic obstructive pulmonary disease (COPD), coadministration with other CNS depressants, cor pulmonale, hypoxemia, respiratory depression, respiratory insufficiency, sleep apnea

    Tramadol; acetaminophen is contraindicated in patients with significant respiratory depression and those with acute or severe asthma in an unmonitored setting or in the absence of resuscitative equipment. Avoid coadministration with other CNS depressants when possible, as this significantly increases the risk for profound sedation, respiratory depression, coma, and death. Reserve concomitant prescribing of these drugs for use in patients for whom alternative treatment options are inadequate; if concurrent use is necessary, use the lowest effective dosages and minimum treatment durations needed. Monitor patients closely for signs or symptoms of respiratory depression and sedation. [61143] Patients with chronic obstructive pulmonary disease (COPD), cor pulmonale, respiratory insufficiency, hypoxemia, hypercapnia, or preexisting respiratory depression are at increased risk of decreased respiratory drive even at recommended doses. Patients with advanced age, cachexia, or debilitation are also at an increased risk for opioid-induced respiratory depression. Monitor such patients closely, particularly when initiating and titrating the opioid; consider the use of non-opioid analgesics in these patients. Opioids increase the risk of central sleep apnea (CSA) and sleep-related hypoxemia in a dose-dependent fashion. Consider decreasing the opioid dosage in patients with CSA. Respiratory depression, if left untreated, may cause respiratory arrest and death. Carbon dioxide retention from respiratory depression may also worsen opioid sedating effects. Careful monitoring and dose titration is required, particularly when CYP3A4 inhibitors or inducers and/or CYP2D6 inhibitors are used concomitantly. The effects of concomitant use or discontinuation of CYP3A4 inhibitors or inducers or CYP2D6 inhibitors on concentrations of tramadol and its active metabolite, M1, are complex and may potentiate the risk of fatal respiratory depression or result in opioid withdrawal and reduced efficacy. Management of respiratory depression may include observation, necessary supportive measures, and opioid antagonist use when indicated.

    Biliary tract disease, GI obstruction, ileus, pancreatitis

    Tramadol is contraindicated in patients with known or suspected GI obstruction, including paralytic ileus. Tramadol may cause spasm of the sphincter of Oddi. Opioids may cause increases in serum amylase. Monitor patients with biliary tract disease, including acute pancreatitis, for worsening symptoms.

    Abrupt discontinuation

    Avoid abrupt discontinuation of tramadol in a physically-dependent patient. When a patient who has been taking opioids regularly and may be physically dependent no longer requires therapy with tramadol, taper the dose gradually while monitoring carefully for signs and symptoms of withdrawal. If the patient develops these signs or symptoms, raise the dose to the previous level and taper more slowly, either by increasing the interval between decreases, decreasing the amount of change in dose, or both. Consider tapering to reduced opioid dosage, or tapering and discontinuing long-term opioid therapy, when pain improves; the patient requests dosage reduction or discontinuation; pain and function are not meaningfully improved; the patient is receiving higher opioid doses without evidence of benefit from the higher dose; the patient has current evidence of opioid misuse; the patient experiences side effects that diminish quality of life or impair function; the patient experiences an overdose or other serious event (e.g., hospitalization, injury) or has warning signs for an impending event such as confusion, sedation, or slurred speech; the patient is receiving medications (e.g., benzodiazepines) or has medical conditions (e.g., lung disease, sleep apnea, liver disease, kidney disease, fall risk, advanced age) that increase risk for adverse outcomes; or the patient has been treated with opioids for a prolonged period and current benefit-harm balance is unclear. If the patient has a serious mental illness, is at high suicide risk, or has suicidal ideation, offer or arrange for consultation with a behavioral health provider before initiating a taper. In patients with opioid use disorder, offer or arrange for medication-assisted treatment. Individualize opioid tapering schedules. The longer the duration of previous opioid therapy, the longer the taper may take. Common tapers involve dose reduction of 5% to 20% every 4 weeks; a faster taper may be appropriate for some patients. Significant opioid withdrawal symptoms may indicate the need to pause or slow the taper. Opioids may be stopped, if appropriate, when taken less often than once daily. Advise patients that there is an increased risk for overdose on abrupt return to a previously prescribed higher dose; provide opioid overdose education, and consider offering naloxone. Monitor patients closely for anxiety, depression, suicidal ideation, and opioid use disorder, and offer support and referral as needed.[64906]

    Brain tumor, CNS depression, coma, head trauma, increased intracranial pressure, intracranial mass

    Avoid tramadol use in patients with CNS depression, impaired consciousness, or coma; opioids may obscure the clinical course in a patient with a head trauma injury. Monitor patients who may be susceptible to the intracranial effect of carbon dioxide retention (e.g., those with evidence of increased intracranial pressure, brain tumor, or intracranial mass) for signs of sedation and respiratory depression, particularly when initiating tramadol therapy. Tramadol may reduce respiratory drive and resultant carbon dioxide retention can further increase intracranial pressure.

    Driving or operating machinery

    Warn patients against performing potentially hazardous activities such as driving or operating machinery unless they are tolerant to the effects of tramadol and know how they will react to the medication. Tramadol may impair mental or physical abilities required to perform such tasks.

    Shock

    Tramadol may cause severe hypotension, including orthostatic hypotension and syncope in ambulatory patients. There is an increased risk in patients whose ability to maintain blood pressure has already been compromised by hypovolemia or concurrent administration of certain CNS depressant drugs (e.g., phenothiazines, general anesthetics). Monitor these patients for signs of hypotension after initiating or titrating the opioid dosage. Avoid the use of tramadol in patients with circulatory shock; it may cause vasodilation that can further reduce cardiac output and blood pressure.

    Seizure disorder, seizures

    Seizures have been reported in patients receiving tramadol within the recommended dosage range; seizure risk is increased with doses of tramadol above the recommended range. Risk of seizure may also increase in patients with a seizure disorder, history of seizures, recognized risk for seizure (such as head trauma, metabolic disorders, alcohol and drug withdrawal, CNS infections), or concomitant use of other drugs that reduce the seizure threshold. In tramadol overdose, naloxone administration may increase the risk of seizure.

    CYP2D6 ultrarapid metabolizers

    Do not use tramadol; acetaminophen in patients who are CYP2D6 ultrarapid metabolizers. Some individuals may be ultrarapid metabolizers due to a specific CYP2D6 genotype (gene duplications noted as *1/*1xN or *1/*2xN). These individuals convert tramadol into its active metabolite, O-desmethyltramadol (M1), more rapidly and completely than other people. This rapid conversion results in higher than expected serum M1 concentrations. Even at labeled dosage regimens, individuals who are ultrarapid metabolizers may have life-threatening or fatal respiratory depression or experience signs of overdose (such as extreme sleepiness, confusion, or shallow breathing). The prevalence of this CYP2D6 phenotype varies widely and has been estimated at 1% to 10% in White patients, 3% to 4% in Black patients, 1% to 2% in East Asian patients (Chinese, Japanese, Korean), and may be greater than 10% in certain racial/ethnic groups (e.g., Oceanian, Northern African, Middle Eastern, Ashkenazi Jews, Puerto Rican). Approximately 7% to 10% of the White patient population lacks functional CYP2D6 activity.

    Geriatric

    Use tramadol; acetaminophen with caution in geriatric patients, starting at the low end of the dosing range and titrating slowly. Monitor for signs of central nervous system and respiratory depression. Geriatric patients may have increased sensitivity to tramadol, reflecting the greater frequency of decreased hepatic, renal, or cardiac function and concomitant disease or other drug therapy. According to the Beers Criteria, caution is recommended when using tramadol in older adults because the drug can cause or exacerbate hyponatremia and SIADH and the elderly are at increased risk of developing these conditions. Sodium concentrations should be closely monitored when starting or changing dosages in older adults. In addition, it is recommended to reduce the dose of immediate-release tramadol in geriatric patients with a creatinine clearance less than 30 mL/minute due to the potential for adverse CNS effects. Opioids are considered potentially inappropriate medications (PIMs) in geriatric patients with a history of falls or fractures and should be avoided in these patient populations, except in the setting of severe acute pain, since opioids can produce ataxia, impaired psychomotor function, syncope, and additional falls. If an opioid must be used, consider reducing the use of other medications that increase the risk of falls and fractures and implement strategies to reduce fall risk.[63923] The federal Omnibus Budget Reconciliation Act (OBRA) regulates medication use in residents of long-term care facilities (LTCFs). Monitor for adverse CNS and gastrointestinal effects, physical and psychological dependency, and unintended respiratory depression, especially in individuals with compromised pulmonary function. Some adverse effects can lead to other consequences such as falls. The initiation of longer-acting opioids is not recommended unless shorter-acting opioids have been unsuccessful, or titration of shorter-acting doses has established a clear daily dose of opioid analgesic that can be provided by using a long-acting form. According to OBRA, daily doses of acetaminophen more than 4 g/day from all sources (alone or as part of combination products) may increase the risk of hepatotoxicity. For acetaminophen doses greater than the maximum recommended daily dose, OBRA guidelines recommend a documented assessment reflecting periodic monitoring of liver function and an indication that the benefits of therapy outweigh the risks.[60742]

    Adenoidectomy, children, infants, neonates, neuromuscular disease, obesity, pulmonary disease, respiratory infection, tonsillectomy

    Tramadol; acetaminophen is contraindicated in neonates, infants, and children younger than 12 years and for postoperative pain management in pediatric patients younger than 18 years after a tonsillectomy and/or adenoidectomy. Avoid use in patients 12 to 18 years of age who have other risk factors for respiratory depression unless the benefits outweigh the risks. Risk factors include conditions associated with hypoventilation such as postoperative status, obstructive sleep apnea, obesity, respiratory infection, asthma, severe pulmonary disease, neuromuscular disease, and concomitant use of other respiratory depressants. When prescribing codeine for adolescents, choose the lowest effective dose for the shortest period of time and inform patients and caregivers of the risks and the signs of opioid overdose. Ultrarapid metabolizers of CYP2D6 substrates may convert tramadol to its active metabolite, O-desmethyltramadol, more quickly and completely than usual, leading to higher than normal opioid blood concentrations that can result in fatal respiratory failure. Because some children who are normal metabolizers can covert opioids at similar rates to ultrarapid metabolizers, this concern extends to all pediatric patients.

    MAOI therapy

    Tramadol is contraindicated in patients receiving MAOI therapy or who have received an MAOI within the previous 14 days due to the risks for potentiation of adverse effects, including confusion, respiratory depression, and coma.

    Labor, neonatal opioid withdrawal syndrome, obstetric delivery, pregnancy

    Data are insufficient to inform a drug-associated risk for major birth defects or miscarriage with tramadol; acetaminophen use in human pregnancy. Tramadol and acetaminophen cross the placenta. Based on animal data, tramadol; acetaminophen may cause fetal harm; advise pregnant women of the potential risk to the fetus. In animal studies of tramadol, decreased fetal weights and reduced ossification were observed in mice, rats, and rabbits at 1.4, 0.6, and 3.6 times the maximum recommended human daily dosage (MRHD). Decreased body weight and increased mortality were observed in pups at tramadol doses of 1.2 and 1.9 times the MRHD. Tramadol; acetaminophen is not recommended for use during and immediately before labor when other analgesic techniques are more appropriate. Opioids can prolong labor and obstetric delivery by temporarily reducing the strength, duration, and frequency of uterine contractions. This effect is not consistent and may be offset by an increased rate of cervical dilatation, which may shorten labor. Opioids cross the placenta and may produce respiratory depression and psycho-physiologic effects in the neonate. Monitor neonates exposed to opioid analgesics during labor for signs of excess sedation and respiratory depression. An opioid antagonist (e.g., naloxone) should be available for reversal of opioid-induced respiratory depression in the neonate. The mean ratio of serum tramadol in the umbilical veins compared to maternal veins was 0.83 for 40 women treated with tramadol during labor. Further, prolonged maternal use of opioids during pregnancy may result in neonatal opioid withdrawal syndrome (NOWS). Monitor the exposed neonate for withdrawal symptoms, including irritability, hyperactivity and abnormal sleep pattern, high-pitched cry, tremor, vomiting, diarrhea, and failure to gain weight, and manage accordingly. Onset, duration, and severity of opioid withdrawal may vary based on the specific opioid used, duration of use, timing and amount of last maternal use, and rate of elimination by the newborn. [55881] Guidelines recommend early universal screening of pregnant patients for opioid use and opioid use disorder at the first prenatal visit. Obtain a thorough history of substance use and review the Prescription Drug Monitoring Program to determine if patients have received prior prescriptions for opioids or other high-risk drugs such as benzodiazepines. Discuss the risks and benefits of opioid use during pregnancy, including the risk of becoming physiologically dependent on opioids, the possibility for NOWS, and how long-term opioid use may affect care during a future pregnancy.[64838] [64909] In women undergoing uncomplicated normal spontaneous vaginal birth, consider opioid therapy only if expected benefits for both pain and function are anticipated to outweigh risks to the patient. If opioids are used, use in combination with nonpharmacologic therapy and nonopioid pharmacologic therapy, as appropriate. Use immediate-release opioids instead of extended-release or long-acting opioids; order the lowest effective dosage and prescribe no greater quantity of opioids than needed for the expected duration of such pain severe enough to require opioids.[64909] For women using opioids for chronic pain, consider strategies to avoid or minimize the use of opioids, including alternative pain therapies (i.e., nonpharmacologic) and nonopioid pharmacologic treatments. Opioid agonist pharmacotherapy (e.g., methadone or buprenorphine) is preferable to medically supervised withdrawal in pregnant women with opioid use disorder.[64838] Published epidemiological studies have not reported a clear association with acetaminophen use during pregnancy and birth defects, miscarriage, or adverse maternal or fetal outcomes. Large observational studies of newborns exposed to oral acetaminophen during the first trimester have not shown an increased risk for congenital malformations or major birth defects; however, these studies cannot definitely establish the absence of risk because of methodological limitations. Acetaminophen does cross the placenta and should be used during pregnancy only if the benefits to the mother outweigh the potential risks to the fetus or infant. No overall increase in fetal mortality, determined by pregnancy outcomes of mothers that overdosed on various amounts of oral acetaminophen, was apparent amongst 300 women. Treatment with acetylcysteine or methionine did not appear to affect fetal or neonatal toxicity. Of 235 infants exposed to an overdose of only acetaminophen, 168 were normal, 8 had malformations, 16 were spontaneously aborted, and 43 were electively terminated. None of the infants with malformations were exposed during the first trimester, but all of the spontaneous abortions were subsequent to first trimester exposure.

    Breast-feeding

    Breast-feeding is not recommended during treatment with tramadol; acetaminophen because of the potential for serious adverse events, including excess sedation and respiratory depression in the breast-fed infant. If an infant is exposed to tramadol through breast milk, monitor the infant for excessive sedation and respiratory depression. Withdrawal symptoms can occur in breast-fed infants when maternal use of an opioid is stopped or when breast-feeding is stopped. Alternative analgesics that previous American Academy of Pediatrics recommendations considered as usually compatible with breast-feeding include acetaminophen, ibuprofen, and morphine. Tramadol and its metabolite (M1) are excreted into human milk. There is no information on the effects of tramadol on milk production. An infant nursing from an ultrarapid metabolizer mother taking tramadol could potentially be exposed to high metabolite concentrations and experience life-threatening respiratory depression. In women with normal tramadol metabolism (normal CYP2D6 activity), the amount of tramadol secreted into human milk is low and dose-dependent. After a single IV dose of tramadol 100 mg, the cumulative excretion in breast milk within 16 hours was 100 mcg of tramadol (0.1% of the maternal dose) and 27 mcg of M1. Samples of breast milk taken from 75 women 2 to 4 days postpartum after receiving at least 4 doses of tramadol indicated that an exclusively breast-fed infant would receive 2.24% of the maternal weight adjusted dose of tramadol and 0.64% of its metabolite. Assessments of the infants of these mothers using the Neurologic and Adaptive Capacity Score found no difference when compared to infants in a control group. Forty-nine percent of mothers in the tramadol group and 100% of mothers in the control group were also receiving other opioids (mostly oxycodone). Limited published studies report acetaminophen passes rapidly into human milk with similar concentrations in the milk and plasma. Average and maximum neonatal doses of 1% and 2%, respectively, of the weight-adjusted maternal dose are reported after a single oral dose of 1,000 mg. There is a well-documented report of rash occurring in a breast-fed infant that resolved with drug discontinuation and recurred with resumption.[42289]

    Infertility, reproductive risk

    Chronic opioid use may influence the hypothalamic-pituitary-gonadal axis, leading to hormonal changes that may manifest as hypogonadism (gonadal suppression) and pose a reproductive risk. Although the exact causal role of opioids in the clinical manifestations of hypogonadism is unknown, patients could experience libido decrease, impotence, amenorrhea, or infertility. It is not known whether the effects on fertility are reversible. Monitor patients for symptoms of opioid-induced endocrinopathy. Patients presenting with signs or symptoms of androgen deficiency should undergo laboratory evaluation.

    ADVERSE REACTIONS

    Severe

    oliguria / Early / 0-1.0
    respiratory arrest / Rapid / Incidence not known
    SIADH / Delayed / Incidence not known
    pulmonary edema / Early / Incidence not known
    torsade de pointes / Rapid / Incidence not known
    renal failure (unspecified) / Delayed / Incidence not known
    renal papillary necrosis / Delayed / Incidence not known
    interstitial nephritis / Delayed / Incidence not known
    renal tubular necrosis / Delayed / Incidence not known
    methemoglobinemia / Early / Incidence not known
    hemolytic anemia / Delayed / Incidence not known
    agranulocytosis / Delayed / Incidence not known
    pancytopenia / Delayed / Incidence not known
    serotonin syndrome / Delayed / Incidence not known
    seizures / Delayed / Incidence not known
    hepatic necrosis / Delayed / Incidence not known
    GI bleeding / Delayed / Incidence not known
    hepatic failure / Delayed / Incidence not known
    hepatotoxicity / Delayed / Incidence not known
    anaphylactic shock / Rapid / Incidence not known
    angioedema / Rapid / Incidence not known
    exfoliative dermatitis / Delayed / Incidence not known
    toxic epidermal necrolysis / Delayed / Incidence not known
    acute generalized exanthematous pustulosis (AGEP) / Delayed / Incidence not known
    anaphylactoid reactions / Rapid / Incidence not known
    bronchospasm / Rapid / Incidence not known
    Stevens-Johnson syndrome / Delayed / Incidence not known
    neonatal opioid withdrawal syndrome / Delayed / Incidence not known
    fetal death / Delayed / Incidence not known

    Moderate

    constipation / Delayed / 6.0-6.0
    melena / Delayed / 0-1.0
    dysphagia / Delayed / 0-1.0
    amnesia / Delayed / 0-1.0
    hallucinations / Early / 0-1.0
    depression / Delayed / 0-1.0
    migraine / Early / 0-1.0
    urinary retention / Early / 0-1.0
    impotence (erectile dysfunction) / Delayed / 0-1.0
    chest pain (unspecified) / Early / 0-1.0
    dyspnea / Early / 0-1.0
    hypotension / Rapid / 0-1.0
    hypertension / Early / 0-1.0
    palpitations / Early / 0-1.0
    sinus tachycardia / Rapid / 0-1.0
    anemia / Delayed / 0-1.0
    hypertonia / Delayed / 0-1.0
    ataxia / Delayed / 0-1.0
    withdrawal / Early / 0-1.0
    confusion / Early / 1.0
    euphoria / Early / 1.0
    hot flashes / Early / 1.0
    respiratory depression / Rapid / Incidence not known
    hyponatremia / Delayed / Incidence not known
    infertility / Delayed / Incidence not known
    adrenocortical insufficiency / Delayed / Incidence not known
    orthostatic hypotension / Delayed / Incidence not known
    QT prolongation / Rapid / Incidence not known
    neutropenia / Delayed / Incidence not known
    thrombocytopenia / Delayed / Incidence not known
    hemolysis / Early / Incidence not known
    thrombocytosis / Delayed / Incidence not known
    elevated hepatic enzymes / Delayed / Incidence not known
    jaundice / Delayed / Incidence not known
    hepatitis / Delayed / Incidence not known
    hypoprothrombinemia / Delayed / Incidence not known
    encephalopathy / Delayed / Incidence not known
    contact dermatitis / Delayed / Incidence not known
    erythema / Early / Incidence not known
    tolerance / Delayed / Incidence not known
    physiological dependence / Delayed / Incidence not known
    psychological dependence / Delayed / Incidence not known
    edema / Delayed / Incidence not known

    Mild

    drowsiness / Early / 6.0-6.0
    hyperhidrosis / Delayed / 4.0-4.0
    diarrhea / Early / 3.0-3.0
    anorexia / Delayed / 3.0-3.0
    nausea / Early / 3.0-3.0
    dizziness / Early / 3.0-3.0
    xerostomia / Early / 2.0-2.0
    insomnia / Early / 2.0-2.0
    pruritus / Rapid / 2.0-2.0
    paranoia / Early / 0-1.0
    syncope / Early / 0-1.0
    emotional lability / Early / 0-1.0
    paresthesias / Delayed / 0-1.0
    nightmares / Early / 0-1.0
    muscle cramps / Delayed / 0-1.0
    chills / Rapid / 0-1.0
    weight loss / Delayed / 0-1.0
    vertigo / Early / 0-1.0
    tinnitus / Delayed / 0-1.0
    dyspepsia / Early / 1.0
    abdominal pain / Early / 1.0
    vomiting / Early / 1.0
    flatulence / Early / 1.0
    tremor / Early / 1.0
    headache / Early / 1.0
    anxiety / Delayed / 1.0
    asthenia / Delayed / 1.0
    rash / Early / 1.0
    fatigue / Early / 1.0
    gonadal suppression / Delayed / Incidence not known
    amenorrhea / Delayed / Incidence not known
    libido decrease / Delayed / Incidence not known
    miosis / Early / Incidence not known
    mydriasis / Early / Incidence not known
    urticaria / Rapid / Incidence not known
    maculopapular rash / Early / Incidence not known
    fever / Early / Incidence not known
    purpura / Delayed / Incidence not known

    DRUG INTERACTIONS

    Abacavir; Lamivudine, 3TC; Zidovudine, ZDV: (Minor) Both acetaminophen and zidovudine, ZDV undergo glucuronidation. Competition for the metabolic pathway is thought to have caused a case of acetaminophen-related hepatotoxicity. This interaction may be more clinically significant in patients with depleted glutathione stores, such as patients with acquired immunodeficiency syndrome, poor nutrition, or alcoholism.
    Abiraterone: (Moderate) Monitor for reduced efficacy of tramadol and signs of opioid withdrawal if coadministration with abiraterone is necessary; also monitor for tramadol-related adverse reactions, including seizures and serotonin syndrome. Consider increasing the dose of tramadol if clinically appropriate. If abiraterone is discontinued, consider a dose reduction of tramadol and frequently monitor for signs or respiratory depression and sedation. Tramadol is metabolized by CYP2D6 to its active metabolite, M1; M1 is critical to the activity of tramadol. Abiraterone is a moderate CYP2D6 inhibitor. Concomitant use with CYP2D6 inhibitors may result in an increase in tramadol plasma levels and a decrease in the levels of the active metabolite, M1. In patients who have developed physical dependence to tramadol, decreased M1 levels may result in opioid withdrawal or reduced efficacy while increased tramadol levels may cause serotonin syndrome or seizures.
    Acetaminophen; Aspirin, ASA; Caffeine: (Moderate) Prolonged concurrent use of acetaminophen and salicylates is not recommended. High-dose, chronic administration of the combined analgesics significantly increases the risk of analgesic nephropathy, renal papillary necrosis, and end-stage renal disease. Do not exceed the recommended individual maximum doses when these agents are given concurrently for short-term therapy.
    Acetaminophen; Caffeine; Dihydrocodeine: (Major) Concomitant use of tramadol increases the seizure risk in patients taking opiate agonists. Also, tramadol can cause additive CNS depression and respiratory depression when used with opiate agonists; avoid concurrent use whenever possible. If used together, extreme caution is needed, and a reduced tramadol dose is recommended.
    Acetaminophen; Caffeine; Magnesium Salicylate; Phenyltoloxamine: (Moderate) Prolonged concurrent use of acetaminophen and salicylates is not recommended. Although salicylates are rarely associated with nephrotoxicity, high-dose, chronic administration of salicylates combined other analgesics, including acetaminophen, significantly increases the risk of analgesic nephropathy, renal papillary necrosis, and end-stage renal disease. Additive hepatic toxicity may occur, especially in combined overdose situations. Do not exceed the recommended individual maximum doses when these agents are given concurrently for short-term therapy.
    Acetaminophen; Chlorpheniramine: (Moderate) Concomitant use of opioid agonists with chlorpheniramine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with chlorpheniramine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Acetaminophen; Chlorpheniramine; Dextromethorphan: (Moderate) Concomitant use of opioid agonists with chlorpheniramine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with chlorpheniramine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Acetaminophen; Chlorpheniramine; Dextromethorphan; Phenylephrine: (Moderate) Concomitant use of opioid agonists with chlorpheniramine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with chlorpheniramine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Acetaminophen; Chlorpheniramine; Dextromethorphan; Pseudoephedrine: (Moderate) Concomitant use of opioid agonists with chlorpheniramine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with chlorpheniramine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Acetaminophen; Chlorpheniramine; Phenylephrine : (Moderate) Concomitant use of opioid agonists with chlorpheniramine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with chlorpheniramine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Acetaminophen; Chlorpheniramine; Phenylephrine; Phenyltoloxamine: (Moderate) Concomitant use of opioid agonists with chlorpheniramine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with chlorpheniramine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Acetaminophen; Codeine: (Major) Concomitant use of tramadol increases the seizure risk in patients taking opiate agonists. Also, tramadol can cause additive CNS depression and respiratory depression when used with opiate agonists; avoid concurrent use whenever possible. If used together, extreme caution is needed, and a reduced tramadol dose is recommended.
    Acetaminophen; Dextromethorphan; Doxylamine: (Moderate) Concomitant use of opioid agonists with doxylamine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with doxylamine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Acetaminophen; Diphenhydramine: (Moderate) Concomitant use of opioid agonists with diphenhydramine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with diphenhydramine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Acetaminophen; Hydrocodone: (Major) Concomitant use of tramadol increases the seizure risk in patients taking opiate agonists. Also, tramadol can cause additive CNS depression and respiratory depression when used with opiate agonists; avoid concurrent use whenever possible. If used together, extreme caution is needed, and a reduced tramadol dose is recommended.
    Acetaminophen; Oxycodone: (Major) Concomitant use of tramadol increases the seizure risk in patients taking opiate agonists. Also, tramadol can cause additive CNS depression and respiratory depression when used with opiate agonists; avoid concurrent use whenever possible. If used together, extreme caution is needed, and a reduced tramadol dose is recommended.
    Acetaminophen; Pamabrom; Pyrilamine: (Moderate) Concomitant use of opioid agonists with pyrilamine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with pyrilamine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Acetaminophen; Pentazocine: (Major) Avoid the concomitant use of pentazocine and opiate agonists, such as tramadol. Pentazocine is a mixed opiate agonist/antagonist that may block the effects of opiate agonists and reduce analgesic effects. Pentazocine may cause withdrawal symptoms in patients receiving chronic opiate agonists. There is also a potential increased risk of seizures if tramadol and pentazocine are given concurrently. Concurrent use of pentazocine with other opiate agonists can cause additive CNS, respiratory, and hypotensive effects. The additive or antagonistic effects are dependent upon the dose of the opiate agonist used; antagonistic effects are more common at low to moderate doses of the opiate agonist.
    Acetaminophen; Propoxyphene: (Major) As propoxyphene is a moderate CYP2D6 inhibitor and tramadol is primarily metabolized by CYP2D6 (and CYP3A4), concurrent therapy may decrease tramadol metabolism. This interaction may result in decreased tramadol efficacy and/or increased tramadol-induced risks of serotonin syndrome or seizures. The analgesic activity of tramadol is due to the activity of both the parent drug and the O-desmethyltramadol metabolite (M1), and M1 formation is dependent on CYP2D6. Therefore, use of tramadol with a CYP2D6-inhibitor may alter tramadol efficacy. In addition, inhibition of either or both CYP2D6 and CYP3A4 is expected to result in reduced metabolic clearance of tramadol. This in turn may increase the risk of tramadol-related adverse events including serotonin syndrome and seizures. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death.
    Acrivastine; Pseudoephedrine: (Major) Avoid coadministration of opioid agonists with acrivastine due to the risk of additive CNS depression.
    Aldesleukin, IL-2: (Moderate) Aldesleukin, IL-2 may affect CNS function significantly. Therefore, psychotropic pharmacodynamic interactions could occur following concomitant administration of drugs with significant CNS or psychotropic activity such as opiate agonists. In addition, aldesleukin, IL-2, is a CYP3A4 inhibitor and may increase oxycodone plasma concentrations and related toxicities including potentially fatal respiratory depression. If therapy with both agents is necessary, monitor patients for an extended period and adjust oxycodone dosage as necessary.
    Alfentanil: (Major) Concomitant use of tramadol increases the seizure risk in patients taking opiate agonists. Also, tramadol can cause additive CNS depression and respiratory depression when used with opiate agonists; avoid concurrent use whenever possible. If used together, extreme caution is needed, and a reduced tramadol dose is recommended.
    Aliskiren; Amlodipine: (Moderate) Consider a tramadol dosage reduction until stable drug effects are achieved if coadministration with amlodipine is necessary. Closely monitor for seizures, serotonin syndrome, and signs of sedation and respiratory depression. Respiratory depression from increased tramadol exposure may be fatal. Concurrent use of amlodipine, a weak CYP3A4 inhibitor, may increase tramadol exposure and result in greater CYP2D6 metabolism thereby increasing exposure to the active metabolite M1, which is a more potent mu-opioid agonist.
    Aliskiren; Amlodipine; Hydrochlorothiazide, HCTZ: (Moderate) Consider a tramadol dosage reduction until stable drug effects are achieved if coadministration with amlodipine is necessary. Closely monitor for seizures, serotonin syndrome, and signs of sedation and respiratory depression. Respiratory depression from increased tramadol exposure may be fatal. Concurrent use of amlodipine, a weak CYP3A4 inhibitor, may increase tramadol exposure and result in greater CYP2D6 metabolism thereby increasing exposure to the active metabolite M1, which is a more potent mu-opioid agonist. (Moderate) Monitor for decreased diuretic efficacy and additive orthostatic hypotension when thiazide diuretics are administered with tramadol. Adjustments to diuretic therapy may be needed in some patients. The efficacy of diuretics may be reduced due to opioid-induced release of antidiuretic hormone.
    Aliskiren; Hydrochlorothiazide, HCTZ: (Moderate) Monitor for decreased diuretic efficacy and additive orthostatic hypotension when thiazide diuretics are administered with tramadol. Adjustments to diuretic therapy may be needed in some patients. The efficacy of diuretics may be reduced due to opioid-induced release of antidiuretic hormone.
    Almotriptan: (Moderate) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering tramadol with serotonin-receptor agonists. Inform patients taking this combination of the possible increased risks and monitor for the emergence of serotonin syndrome particularly during treatment initiation and dose adjustment. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs.
    Alosetron: (Major) Patients taking medications that decrease GI motility may be at greater risk for serious complications from alosetron, like constipation, via a pharmacodynamic interaction. Constipation is the most frequently reported adverse effect with alosetron. Alosetron, if used with drugs such as opiate agonists, may seriously worsen constipation, leading to events such as GI obstruction/impaction or paralytic ileus.
    Alprazolam: (Major) Concomitant use of opiate agonists with benzodiazepines may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opiate pain medications with benzodiazepines to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If an opiate agonist is initiated in a patient taking a benzodiazepine, use a lower initial dose of the opiate and titrate to clinical response. If a benzodiazepine is prescribed for an indication other than epilepsy in a patient taking an opiate agonist, use a lower initial dose of the benzodiazepine and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Alvimopan: (Moderate) Patients should not take alvimopan if they have received therapeutic doses of opiate agonists for more than seven consecutive days immediately before initiation of alvimopan therapy. Patients recently exposed to opioids are expected to be more sensitive to the effects of mu-opioid receptor antagonists and may experience adverse effects localized to the gastrointestinal tract such as abdominal pain, nausea, vomiting, and diarrhea.
    Amifampridine: (Major) Carefully consider concomitant use of amifampridine with tramadol due to increased seizure risk. The concomitant use of amifampridine and other drugs that lower the seizure threshold, such as tramadol, may lead to an increased risk of seizures.
    Amiloride: (Moderate) Monitor for decreased diuretic efficacy and additive orthostatic hypotension when amiloride is administered with tramadol. Adjustments to diuretic therapy may be needed in some patients. The efficacy of diuretics may be reduced due to opioid-induced release of antidiuretic hormone.
    Amiloride; Hydrochlorothiazide, HCTZ: (Moderate) Monitor for decreased diuretic efficacy and additive orthostatic hypotension when amiloride is administered with tramadol. Adjustments to diuretic therapy may be needed in some patients. The efficacy of diuretics may be reduced due to opioid-induced release of antidiuretic hormone. (Moderate) Monitor for decreased diuretic efficacy and additive orthostatic hypotension when thiazide diuretics are administered with tramadol. Adjustments to diuretic therapy may be needed in some patients. The efficacy of diuretics may be reduced due to opioid-induced release of antidiuretic hormone.
    Amiodarone: (Moderate) Use of amiodarone concurrently with tramadol may inhibit tramadol metabolism. Decreased efficacy and possibly increased side effects may occur due to increased tramadol serum concentrations and decreased serum concentrations of the active metabolite.
    Amlodipine: (Moderate) Consider a tramadol dosage reduction until stable drug effects are achieved if coadministration with amlodipine is necessary. Closely monitor for seizures, serotonin syndrome, and signs of sedation and respiratory depression. Respiratory depression from increased tramadol exposure may be fatal. Concurrent use of amlodipine, a weak CYP3A4 inhibitor, may increase tramadol exposure and result in greater CYP2D6 metabolism thereby increasing exposure to the active metabolite M1, which is a more potent mu-opioid agonist.
    Amlodipine; Atorvastatin: (Moderate) Consider a tramadol dosage reduction until stable drug effects are achieved if coadministration with amlodipine is necessary. Closely monitor for seizures, serotonin syndrome, and signs of sedation and respiratory depression. Respiratory depression from increased tramadol exposure may be fatal. Concurrent use of amlodipine, a weak CYP3A4 inhibitor, may increase tramadol exposure and result in greater CYP2D6 metabolism thereby increasing exposure to the active metabolite M1, which is a more potent mu-opioid agonist.
    Amlodipine; Benazepril: (Moderate) Consider a tramadol dosage reduction until stable drug effects are achieved if coadministration with amlodipine is necessary. Closely monitor for seizures, serotonin syndrome, and signs of sedation and respiratory depression. Respiratory depression from increased tramadol exposure may be fatal. Concurrent use of amlodipine, a weak CYP3A4 inhibitor, may increase tramadol exposure and result in greater CYP2D6 metabolism thereby increasing exposure to the active metabolite M1, which is a more potent mu-opioid agonist.
    Amlodipine; Celecoxib: (Moderate) Consider a tramadol dosage reduction until stable drug effects are achieved if coadministration with amlodipine is necessary. Closely monitor for seizures, serotonin syndrome, and signs of sedation and respiratory depression. Respiratory depression from increased tramadol exposure may be fatal. Concurrent use of amlodipine, a weak CYP3A4 inhibitor, may increase tramadol exposure and result in greater CYP2D6 metabolism thereby increasing exposure to the active metabolite M1, which is a more potent mu-opioid agonist. (Moderate) Monitor for reduced efficacy of tramadol and signs of opioid withdrawal if coadministration with celecoxib is necessary; also monitor for tramadol-related adverse reactions, including seizures and serotonin syndrome. Consider increasing the dose of tramadol if clinically appropriate. If celecoxib is discontinued, consider a dose reduction of tramadol and frequently monitor for signs or respiratory depression and sedation. Tramadol is metabolized by CYP2D6 to its active metabolite, M1; M1 is critical to the activity of tramadol. Celecoxib is a CYP2D6 inhibitor. Concomitant use with CYP2D6 inhibitors may result in an increase in tramadol plasma concentrations and a decrease in the concentrations of the active metabolite, M1. In patients who have developed physical dependence to tramadol, decreased M1 concentrations may result in opioid withdrawal or reduced efficacy while increased tramadol concentrations may cause serotonin syndrome or seizures.
    Amlodipine; Olmesartan: (Moderate) Consider a tramadol dosage reduction until stable drug effects are achieved if coadministration with amlodipine is necessary. Closely monitor for seizures, serotonin syndrome, and signs of sedation and respiratory depression. Respiratory depression from increased tramadol exposure may be fatal. Concurrent use of amlodipine, a weak CYP3A4 inhibitor, may increase tramadol exposure and result in greater CYP2D6 metabolism thereby increasing exposure to the active metabolite M1, which is a more potent mu-opioid agonist.
    Amlodipine; Valsartan: (Moderate) Consider a tramadol dosage reduction until stable drug effects are achieved if coadministration with amlodipine is necessary. Closely monitor for seizures, serotonin syndrome, and signs of sedation and respiratory depression. Respiratory depression from increased tramadol exposure may be fatal. Concurrent use of amlodipine, a weak CYP3A4 inhibitor, may increase tramadol exposure and result in greater CYP2D6 metabolism thereby increasing exposure to the active metabolite M1, which is a more potent mu-opioid agonist.
    Amlodipine; Valsartan; Hydrochlorothiazide, HCTZ: (Moderate) Consider a tramadol dosage reduction until stable drug effects are achieved if coadministration with amlodipine is necessary. Closely monitor for seizures, serotonin syndrome, and signs of sedation and respiratory depression. Respiratory depression from increased tramadol exposure may be fatal. Concurrent use of amlodipine, a weak CYP3A4 inhibitor, may increase tramadol exposure and result in greater CYP2D6 metabolism thereby increasing exposure to the active metabolite M1, which is a more potent mu-opioid agonist. (Moderate) Monitor for decreased diuretic efficacy and additive orthostatic hypotension when thiazide diuretics are administered with tramadol. Adjustments to diuretic therapy may be needed in some patients. The efficacy of diuretics may be reduced due to opioid-induced release of antidiuretic hormone.
    Amobarbital: (Major) Concomitant use of tramadol with barbiturates may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medications with barbiturates to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation. Additionally, concomitant use of tramadol with a barbiturate can decrease tramadol concentrations; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence. Monitor for reduced efficacy of tramadol and signs of opioid withdrawal. Discontinuation of a barbiturate may increase the risk of seizures, serotonin syndrome, and the risk of opioid-related adverse reactions, such as fatal respiratory depression. Barbiturates induce CYP3A4; tramadol is a CYP3A4 substrate. (Minor) Chronic therapy with barbiturates can increase the metabolism and decrease the effectiveness of acetaminophen. During acute overdoses, barbiturates can enhance the formation of toxic acetaminophen metabolites.
    Amoxapine: (Major) Concomitant use of tramadol with amoxapine may cause excessive sedation and somnolence and increase the risk for seizures. Limit the use of tramadol with amoxapine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. Educate patients about the risks and symptoms of excessive CNS depression and the potential increased risk for seizures.
    Amphetamine; Dextroamphetamine Salts: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering amphetamines with other drugs that have serotonergic properties such as tramadol. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Further study is needed to fully elucidate the severity and frequency of adverse effects that may occur from concomitant administration of amphetamines and tramadol. Patients receiving tramadol and an amphetamine should be monitored for the emergence of serotonin syndrome, particularly during treatment initiation and during dosage increases. The amphetamine and tramadol should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated. In addition, the risk of seizures from the use of tramadol may be increased with concomitant use of CNS stimulants that may induce seizures, including the amphetamines. Extreme caution and close clinical monitoring is recommended if these agents must be used together.
    Antacids: (Minor) Antacids can delay the oral absorption of acetaminophen, but the interactions are not likely to be clinically significant as the extent of acetaminophen absorption is not appreciably affected.
    Anticholinergics: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when tramadol is used concomitantly with an anticholinergic drug. The concomitant use of tramadol and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Apalutamide: (Moderate) Monitor for reduced efficacy of tramadol and signs of opioid withdrawal if coadministration with apalutamide is necessary; consider increasing the dose of tramadol as needed. If apalutamide is discontinued, consider a dose reduction of tramadol and frequently monitor for signs or respiratory depression and sedation. Tramadol is a CYP3A4 substrate and apalutamide is a strong CYP3A4 inducer. Concomitant use with CYP3A4 inducers can decrease tramadol levels; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence.
    Apomorphine: (Major) Concomitant use of opioid agonists with apomorphine may cause excessive sedation and somnolence. Limit the use of opioid pain medications with apomorphine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. Educate patients about the risks and symptoms of excessive CNS depression. Dopaminergic agents like apomorphine have also been associated with sudden sleep onset during activities of daily living such as driving, which has resulted in accidents in some cases. Prescribers should re-assess patients for drowsiness or sleepiness regularly throughout treatment, especially since events may occur well after the start of treatment.
    Apraclonidine: (Minor) Theoretically, apraclonidine might potentiate the effects of CNS depressant drugs such as opiate agonists. Although no specific drug interactions were identified with systemic agents and apraclonidine during clinical trials, apraclonidine can cause dizziness and somnolence.
    Aprepitant, Fosaprepitant: (Moderate) Use caution if tramadol and aprepitant, fosaprepitant are used concurrently and monitor for an increase in tramadol-related adverse effects for several days after administration of a multi-day aprepitant regimen. Tramadol is a CYP3A4 substrate. Aprepitant, when administered as a 3-day oral regimen (125 mg/80 mg/80 mg), is a moderate CYP3A4 inhibitor and inducer and may increase plasma concentrations of tramadol. For example, a 5-day oral aprepitant regimen increased the AUC of another CYP3A4 substrate, midazolam (single dose), by 2.3-fold on day 1 and by 3.3-fold on day 5. After a 3-day oral aprepitant regimen, the AUC of midazolam (given on days 1, 4, 8, and 15) increased by 25% on day 4, and then decreased by 19% and 4% on days 8 and 15, respectively. As a single 125 mg or 40 mg oral dose, the inhibitory effect of aprepitant on CYP3A4 is weak, with the AUC of midazolam increased by 1.5-fold and 1.2-fold, respectively. After administration, fosaprepitant is rapidly converted to aprepitant and shares many of the same drug interactions. However, as a single 150 mg intravenous dose, fosaprepitant only weakly inhibits CYP3A4 for a duration of 2 days; there is no evidence of CYP3A4 induction. Fosaprepitant 150 mg IV as a single dose increased the AUC of midazolam (given on days 1 and 4) by approximately 1.8-fold on day 1; there was no effect on day 4. Less than a 2-fold increase in the midazolam AUC is not considered clinically important. (Minor) Use caution if acetaminophen and aprepitant are used concurrently and monitor for an increase in acetaminophen-related adverse effects for several days after administration of a multi-day aprepitant regimen. Acetaminophen is a minor (10 to 15%) substrate of CYP3A4. Aprepitant, when administered as a 3-day oral regimen (125 mg/80 mg/80 mg), is a moderate CYP3A4 inhibitor and inducer and may increase plasma concentrations of acetaminophen. For example, a 5-day oral aprepitant regimen increased the AUC of another CYP3A4 substrate, midazolam (single dose), by 2.3-fold on day 1 and by 3.3-fold on day 5. After a 3-day oral aprepitant regimen, the AUC of midazolam (given on days 1, 4, 8, and 15) increased by 25% on day 4, and then decreased by 19% and 4% on days 8 and 15, respectively. As a single 125 mg or 40 mg oral dose, the inhibitory effect of aprepitant on CYP3A4 is weak, with the AUC of midazolam increased by 1.5-fold and 1.2-fold, respectively. After administration, fosaprepitant is rapidly converted to aprepitant and shares many of the same drug interactions. However, as a single 150 mg intravenous dose, fosaprepitant only weakly inhibits CYP3A4 for a duration of 2 days; there is no evidence of CYP3A4 induction. Fosaprepitant 150 mg IV as a single dose increased the AUC of midazolam (given on days 1 and 4) by approximately 1.8-fold on day 1; there was no effect on day 4. Less than a 2-fold increase in the midazolam AUC is not considered clinically important.
    Aripiprazole: (Moderate) Concomitant use of tramadol with aripiprazole may cause excessive sedation, somnolence, and increased risk of seizure. Limit the use of tramadol with aripiprazole to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. Educate patients about the risks and symptoms of excessive CNS depression and seizures.
    Artemether; Lumefantrine: (Moderate) Lumefantrine is an inhibitor and tramadol is a substrate/inhibitor of the CYP2D6 isoenzyme; therefore, coadministration may lead to increased tramadol concentrations. Concomitant use warrants caution due to the potential for increased side effects.
    Articaine; Epinephrine: (Moderate) Coadministration of articaine with oxidizing agents, such as acetaminophen, may increase the risk of developing methemoglobinemia. Monitor patients closely for signs and symptoms of methemoglobinemia if coadministration is necessary. If methemoglobinemia occurs or is suspected, discontinue articaine and any other oxidizing agents. Depending on the severity of symptoms, patients may respond to supportive care; more severe symptoms may require treatment with methylene blue, exchange transfusion, or hyperbaric oxygen.
    Asciminib: (Moderate) Consider a tramadol dosage reduction until stable drug effects are achieved if coadministration with asciminib is necessary. Closely monitor for seizures, serotonin syndrome, and signs of sedation and respiratory depression. Respiratory depression from increased tramadol exposure may be fatal. Concurrent use of asciminib, a weak CYP3A inhibitor, may increase tramadol exposure and result in greater CYP2D6 metabolism thereby increasing exposure to the active metabolite M1, which is a more potent mu-opioid agonist.
    Asenapine: (Moderate) Concomitant use of tramadol with asenapine may cause excessive sedation, somnolence, and increased risk of seizure. Limit the use of tramadol with asenapine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. Educate patients about the risks and symptoms of excessive CNS depression and seizures.
    Aspirin, ASA: (Moderate) Prolonged concurrent use of acetaminophen and salicylates is not recommended. High-dose, chronic administration of the combined analgesics significantly increases the risk of analgesic nephropathy, renal papillary necrosis, and end-stage renal disease. Do not exceed the recommended individual maximum doses when these agents are given concurrently for short-term therapy.
    Aspirin, ASA; Butalbital; Caffeine: (Major) Concomitant use of tramadol with barbiturates may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medications with barbiturates to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation. Additionally, concomitant use of tramadol with a barbiturate can decrease tramadol concentrations; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence. Monitor for reduced efficacy of tramadol and signs of opioid withdrawal. Discontinuation of a barbiturate may increase the risk of seizures, serotonin syndrome, and the risk of opioid-related adverse reactions, such as fatal respiratory depression. Barbiturates induce CYP3A4; tramadol is a CYP3A4 substrate. (Moderate) Prolonged concurrent use of acetaminophen and salicylates is not recommended. High-dose, chronic administration of the combined analgesics significantly increases the risk of analgesic nephropathy, renal papillary necrosis, and end-stage renal disease. Do not exceed the recommended individual maximum doses when these agents are given concurrently for short-term therapy. (Minor) Chronic therapy with barbiturates can increase the metabolism and decrease the effectiveness of acetaminophen. During acute overdoses, barbiturates can enhance the formation of toxic acetaminophen metabolites.
    Aspirin, ASA; Butalbital; Caffeine; Codeine: (Major) Concomitant use of tramadol increases the seizure risk in patients taking opiate agonists. Also, tramadol can cause additive CNS depression and respiratory depression when used with opiate agonists; avoid concurrent use whenever possible. If used together, extreme caution is needed, and a reduced tramadol dose is recommended. (Major) Concomitant use of tramadol with barbiturates may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medications with barbiturates to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation. Additionally, concomitant use of tramadol with a barbiturate can decrease tramadol concentrations; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence. Monitor for reduced efficacy of tramadol and signs of opioid withdrawal. Discontinuation of a barbiturate may increase the risk of seizures, serotonin syndrome, and the risk of opioid-related adverse reactions, such as fatal respiratory depression. Barbiturates induce CYP3A4; tramadol is a CYP3A4 substrate. (Moderate) Prolonged concurrent use of acetaminophen and salicylates is not recommended. High-dose, chronic administration of the combined analgesics significantly increases the risk of analgesic nephropathy, renal papillary necrosis, and end-stage renal disease. Do not exceed the recommended individual maximum doses when these agents are given concurrently for short-term therapy. (Minor) Chronic therapy with barbiturates can increase the metabolism and decrease the effectiveness of acetaminophen. During acute overdoses, barbiturates can enhance the formation of toxic acetaminophen metabolites.
    Aspirin, ASA; Caffeine: (Moderate) Prolonged concurrent use of acetaminophen and salicylates is not recommended. High-dose, chronic administration of the combined analgesics significantly increases the risk of analgesic nephropathy, renal papillary necrosis, and end-stage renal disease. Do not exceed the recommended individual maximum doses when these agents are given concurrently for short-term therapy.
    Aspirin, ASA; Caffeine; Dihydrocodeine: (Major) Concomitant use of tramadol increases the seizure risk in patients taking opiate agonists. Also, tramadol can cause additive CNS depression and respiratory depression when used with opiate agonists; avoid concurrent use whenever possible. If used together, extreme caution is needed, and a reduced tramadol dose is recommended. (Moderate) Prolonged concurrent use of acetaminophen and salicylates is not recommended. High-dose, chronic administration of the combined analgesics significantly increases the risk of analgesic nephropathy, renal papillary necrosis, and end-stage renal disease. Do not exceed the recommended individual maximum doses when these agents are given concurrently for short-term therapy.
    Aspirin, ASA; Caffeine; Orphenadrine: (Major) Concomitant use of tramadol with a skeletal muscle relaxant may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medications with a skeletal muscle relaxant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation. (Moderate) Prolonged concurrent use of acetaminophen and salicylates is not recommended. High-dose, chronic administration of the combined analgesics significantly increases the risk of analgesic nephropathy, renal papillary necrosis, and end-stage renal disease. Do not exceed the recommended individual maximum doses when these agents are given concurrently for short-term therapy.
    Aspirin, ASA; Carisoprodol: (Major) Concomitant use of tramadol with a skeletal muscle relaxant may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medications with a skeletal muscle relaxant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation. (Moderate) Prolonged concurrent use of acetaminophen and salicylates is not recommended. High-dose, chronic administration of the combined analgesics significantly increases the risk of analgesic nephropathy, renal papillary necrosis, and end-stage renal disease. Do not exceed the recommended individual maximum doses when these agents are given concurrently for short-term therapy.
    Aspirin, ASA; Carisoprodol; Codeine: (Major) Concomitant use of tramadol increases the seizure risk in patients taking opiate agonists. Also, tramadol can cause additive CNS depression and respiratory depression when used with opiate agonists; avoid concurrent use whenever possible. If used together, extreme caution is needed, and a reduced tramadol dose is recommended. (Major) Concomitant use of tramadol with a skeletal muscle relaxant may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medications with a skeletal muscle relaxant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation. (Moderate) Prolonged concurrent use of acetaminophen and salicylates is not recommended. High-dose, chronic administration of the combined analgesics significantly increases the risk of analgesic nephropathy, renal papillary necrosis, and end-stage renal disease. Do not exceed the recommended individual maximum doses when these agents are given concurrently for short-term therapy.
    Aspirin, ASA; Citric Acid; Sodium Bicarbonate: (Moderate) Prolonged concurrent use of acetaminophen and salicylates is not recommended. High-dose, chronic administration of the combined analgesics significantly increases the risk of analgesic nephropathy, renal papillary necrosis, and end-stage renal disease. Do not exceed the recommended individual maximum doses when these agents are given concurrently for short-term therapy. (Minor) Antacids can delay the oral absorption of acetaminophen, but the interactions are not likely to be clinically significant as the extent of acetaminophen absorption is not appreciably affected.
    Aspirin, ASA; Dipyridamole: (Moderate) Prolonged concurrent use of acetaminophen and salicylates is not recommended. High-dose, chronic administration of the combined analgesics significantly increases the risk of analgesic nephropathy, renal papillary necrosis, and end-stage renal disease. Do not exceed the recommended individual maximum doses when these agents are given concurrently for short-term therapy.
    Aspirin, ASA; Omeprazole: (Moderate) Prolonged concurrent use of acetaminophen and salicylates is not recommended. High-dose, chronic administration of the combined analgesics significantly increases the risk of analgesic nephropathy, renal papillary necrosis, and end-stage renal disease. Do not exceed the recommended individual maximum doses when these agents are given concurrently for short-term therapy.
    Aspirin, ASA; Oxycodone: (Major) Concomitant use of tramadol increases the seizure risk in patients taking opiate agonists. Also, tramadol can cause additive CNS depression and respiratory depression when used with opiate agonists; avoid concurrent use whenever possible. If used together, extreme caution is needed, and a reduced tramadol dose is recommended. (Moderate) Prolonged concurrent use of acetaminophen and salicylates is not recommended. High-dose, chronic administration of the combined analgesics significantly increases the risk of analgesic nephropathy, renal papillary necrosis, and end-stage renal disease. Do not exceed the recommended individual maximum doses when these agents are given concurrently for short-term therapy.
    Aspirin, ASA; Pravastatin: (Moderate) Prolonged concurrent use of acetaminophen and salicylates is not recommended. High-dose, chronic administration of the combined analgesics significantly increases the risk of analgesic nephropathy, renal papillary necrosis, and end-stage renal disease. Do not exceed the recommended individual maximum doses when these agents are given concurrently for short-term therapy.
    Atazanavir; Cobicistat: (Major) As cobicistat is a CYP2D6 and CYP3A4 inhibitor and tramadol is primarily metabolized by CYP2D6 and CYP3A4, concurrent therapy may decrease tramadol metabolism; reduced tramadol dose may be needed during coadministration. This interaction may result in decreased tramadol efficacy and/or increased tramadol-induced risks of serotonin syndrome or seizures. The analgesic activity of tramadol is due to the activity of both the parent drug and the O-desmethyltramadol metabolite (M1), and M1 formation is dependent on CYP2D6. Therefore, use of tramadol with a CYP2D6-inhibitor may alter tramadol efficacy. In addition, inhibition of either or both CYP2D6 and CYP3A4 is expected to result in reduced metabolic clearance of tramadol. This in turn may increase the risk of tramadol-related adverse events including serotonin syndrome and seizures. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death.
    Atenolol; Chlorthalidone: (Moderate) Monitor for decreased diuretic efficacy and additive orthostatic hypotension when thiazide diuretics are administered with tramadol. Adjustments to diuretic therapy may be needed in some patients. The efficacy of diuretics may be reduced due to opioid-induced release of antidiuretic hormone.
    Atropine: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when tramadol is used concomitantly with an anticholinergic drug. The concomitant use of tramadol and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Atropine; Benzoic Acid; Hyoscyamine; Methenamine; Methylene Blue; Phenyl Salicylate: (Contraindicated) Tramadol use is contraindicated in patients who are receiving or who have received monoamine oxidase inhibitors (MAOIs) within the previous 14 days. Methylene blue is a reversible inhibitor of MAO. Concomitant use of tramadol with other serotonergic drugs such as MAOIs may result in serious adverse effects including serotonin syndrome or seizures. MAOIs may cause additive CNS depression, respiratory depression, drowsiness, dizziness, or hypotension when used with opiate agonists such as tramadol. (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when tramadol is used concomitantly with an anticholinergic drug. The concomitant use of tramadol and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Atropine; Difenoxin: (Moderate) Concurrent administration of diphenoxylate/difenoxin with other opiate agonists can potentiate the CNS-depressant effects of diphenoxylate/difenoxin. Use caution during coadministration. In addition, diphenoxylate/difenoxin use may cause constipation; cases of severe GI reactions including toxic megacolon and adynamic ileus have been reported. Reduced GI motility when combined with opiate agonists may increase the risk of serious GI related adverse events. (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when tramadol is used concomitantly with an anticholinergic drug. The concomitant use of tramadol and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Atropine; Edrophonium: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when tramadol is used concomitantly with an anticholinergic drug. The concomitant use of tramadol and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Avacopan: (Moderate) Consider a tramadol dosage reduction until stable drug effects are achieved if coadministration with avacopan is necessary. Closely monitor for seizures, serotonin syndrome, and signs of sedation and respiratory depression. Respiratory depression from increased tramadol exposure may be fatal. Concurrent use of avacopan, a weak CYP3A inhibitor, may increase tramadol exposure and result in greater CYP2D6 metabolism thereby increasing exposure to the active metabolite M1, which is a more potent mu-opioid agonist.
    Azelastine: (Major) Concomitant use of opioid agonists with azelastine may cause excessive sedation and somnolence. Limit the use of opioid pain medications with azelastine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. Educate patients about the risks and symptoms of excessive CNS depression.
    Azelastine; Fluticasone: (Major) Concomitant use of opioid agonists with azelastine may cause excessive sedation and somnolence. Limit the use of opioid pain medications with azelastine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. Educate patients about the risks and symptoms of excessive CNS depression.
    Azilsartan; Chlorthalidone: (Moderate) Monitor for decreased diuretic efficacy and additive orthostatic hypotension when thiazide diuretics are administered with tramadol. Adjustments to diuretic therapy may be needed in some patients. The efficacy of diuretics may be reduced due to opioid-induced release of antidiuretic hormone.
    Baclofen: (Major) Concomitant use of tramadol with a skeletal muscle relaxant may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medications with a skeletal muscle relaxant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Barbiturates: (Major) Concomitant use of tramadol with barbiturates may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medications with barbiturates to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation. Additionally, concomitant use of tramadol with a barbiturate can decrease tramadol concentrations; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence. Monitor for reduced efficacy of tramadol and signs of opioid withdrawal. Discontinuation of a barbiturate may increase the risk of seizures, serotonin syndrome, and the risk of opioid-related adverse reactions, such as fatal respiratory depression. Barbiturates induce CYP3A4; tramadol is a CYP3A4 substrate. (Minor) Chronic therapy with barbiturates can increase the metabolism and decrease the effectiveness of acetaminophen. During acute overdoses, barbiturates can enhance the formation of toxic acetaminophen metabolites.
    Belladonna Alkaloids; Ergotamine; Phenobarbital: (Major) Concomitant use of tramadol with barbiturates may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medications with barbiturates to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation. Additionally, concomitant use of tramadol with a barbiturate can decrease tramadol concentrations; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence. Monitor for reduced efficacy of tramadol and signs of opioid withdrawal. Discontinuation of a barbiturate may increase the risk of seizures, serotonin syndrome, and the risk of opioid-related adverse reactions, such as fatal respiratory depression. Barbiturates induce CYP3A4; tramadol is a CYP3A4 substrate. (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when tramadol is used concomitantly with an anticholinergic drug. The concomitant use of tramadol and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect. (Minor) Chronic therapy with barbiturates can increase the metabolism and decrease the effectiveness of acetaminophen. During acute overdoses, barbiturates can enhance the formation of toxic acetaminophen metabolites.
    Belladonna; Opium: (Major) Concomitant use of tramadol increases the seizure risk in patients taking opiate agonists. Also, tramadol can cause additive CNS depression and respiratory depression when used with opiate agonists; avoid concurrent use whenever possible. If used together, extreme caution is needed, and a reduced tramadol dose is recommended. (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when tramadol is used concomitantly with an anticholinergic drug. The concomitant use of tramadol and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Belumosudil: (Moderate) Consider a tramadol dosage reduction until stable drug effects are achieved if coadministration with belumosudil is necessary. Closely monitor for seizures, serotonin syndrome, and signs of sedation and respiratory depression. Respiratory depression from increased tramadol exposure may be fatal. Concurrent use of belumosudil, a weak CYP3A inhibitor, may increase tramadol exposure and result in greater CYP2D6 metabolism thereby increasing exposure to the active metabolite M1, which is a more potent mu-opioid agonist.
    Belzutifan: (Moderate) Monitor for reduced efficacy of tramadol and signs of opioid withdrawal if coadministration with belzutifan is necessary; consider increasing the dose of tramadol as needed. If belzutifan is discontinued, consider a dose reduction of tramadol and frequently monitor for seizures, serotonin syndrome, and signs of respiratory depression and sedation. Tramadol is a CYP3A substrate and belzutifan is a weak CYP3A inducer. Concomitant use with CYP3A inducers can decrease tramadol levels; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence.
    Benazepril; Hydrochlorothiazide, HCTZ: (Moderate) Monitor for decreased diuretic efficacy and additive orthostatic hypotension when thiazide diuretics are administered with tramadol. Adjustments to diuretic therapy may be needed in some patients. The efficacy of diuretics may be reduced due to opioid-induced release of antidiuretic hormone.
    Bendroflumethiazide; Nadolol: (Moderate) Monitor for decreased diuretic efficacy and additive orthostatic hypotension when thiazide diuretics are administered with tramadol. Adjustments to diuretic therapy may be needed in some patients. The efficacy of diuretics may be reduced due to opioid-induced release of antidiuretic hormone.
    Benzhydrocodone; Acetaminophen: (Major) Concomitant use of other opiate agonists with tramadol may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of other opiate pain medications with tramadol to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If benzhydrocodone is initiated in a patient taking tramadol, reduce the initial dosage and titrate to clinical response. If tramadol is prescribed in a patient taking benzhydrocodone, use a lower initial dose of tramadol and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation. Careful monitoring, particularly during treatment initiation and dose adjustment, is recommended during coadministration of benzhydrocodone and tramadol because of the potential risk of serotonin syndrome. Discontinue benzhydrocodone if serotonin syndrome is suspected. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. Concomitant use of tramadol increases the seizure risk in patients taking other opiate agonists.
    Benzoic Acid; Hyoscyamine; Methenamine; Methylene Blue; Phenyl Salicylate: (Contraindicated) Tramadol use is contraindicated in patients who are receiving or who have received monoamine oxidase inhibitors (MAOIs) within the previous 14 days. Methylene blue is a reversible inhibitor of MAO. Concomitant use of tramadol with other serotonergic drugs such as MAOIs may result in serious adverse effects including serotonin syndrome or seizures. MAOIs may cause additive CNS depression, respiratory depression, drowsiness, dizziness, or hypotension when used with opiate agonists such as tramadol. (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when tramadol is used concomitantly with an anticholinergic drug. The concomitant use of tramadol and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Benzphetamine: (Moderate) Serotonin syndrome may occur during coadministration of serotonergic drugs such as amphetamines and tramadol. At high doses, amphetamines can increase serotonin release, as well as act as serotonin agonists. An additive risk of seizures is also possible. Inform patients taking this combination of the possible increased risk of serotonin syndrome and seizures and monitor for adverse effects particularly after a dose increase or the addition of interacting medications. Discontinue all serotonergic agents if serotonin syndrome occurs and implement appropriate medical management.
    Benztropine: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when tramadol is used concomitantly with an anticholinergic drug. The concomitant use of tramadol and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Berotralstat: (Moderate) Concurrent use of tramadol with berotralstat may produce unpredictable effects, including prolonged opioid-related adverse reactions, such as fatal respiratory depression, a withdrawal syndrome in those with physical dependence to opioid agonists, seizures, or serotonin syndrome. Consider dose adjustments of tramadol until stable drug effects are achieved. Monitor patients closely for respiratory depression and sedation at frequent intervals. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. Tramadol is primarily metabolized by CYP2D6 to the active metabolite M1, and by CYP3A4; berotralstat is a moderate inhibitor of CYP3A4 and CYP2D6. CYP3A4 inhibitors may increase tramadol-related adverse effects while CYP2D6 inhibitors may reduce efficacy.
    Bethanechol: (Moderate) Bethanechol facilitates intestinal and bladder function via parasympathomimetic actions. Opiate agonists impair the peristaltic activity of the intestine. Thus, these drugs can antagonize the beneficial actions of bethanechol on GI motility.
    Bicalutamide: (Moderate) Consider a tramadol dosage reduction until stable drug effects are achieved if coadministration with bicalutamide is necessary. Closely monitor for seizures, serotonin syndrome, and signs of sedation and respiratory depression. Respiratory depression from increased tramadol exposure may be fatal. Concurrent use of bicalutamide, a weak CYP3A4 inhibitor, may increase tramadol exposure and result in greater CYP2D6 metabolism thereby increasing exposure to the active metabolite M1, which is a more potent mu-opioid agonist.
    Bismuth Subcitrate Potassium; Metronidazole; Tetracycline: (Moderate) Additive constipation may be seen with concurrent use of opiate agonists and antidiarrheals. Opioids increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Bismuth Subsalicylate: (Moderate) Additive constipation may be seen with concurrent use of opiate agonists and antidiarrheals. Opioids increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect. (Moderate) Prolonged concurrent use of acetaminophen and salicylates is not recommended. Although salicylates are rarely associated with nephrotoxicity, high-dose, chronic administration of salicylates combined other analgesics, including acetaminophen, significantly increases the risk of analgesic nephropathy, renal papillary necrosis, and end-stage renal disease. Additive hepatic toxicity may occur, especially in combined overdose situations. Do not exceed the recommended individual maximum doses when these agents are given concurrently for short-term therapy.
    Bismuth Subsalicylate; Metronidazole; Tetracycline: (Moderate) Additive constipation may be seen with concurrent use of opiate agonists and antidiarrheals. Opioids increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect. (Moderate) Prolonged concurrent use of acetaminophen and salicylates is not recommended. Although salicylates are rarely associated with nephrotoxicity, high-dose, chronic administration of salicylates combined other analgesics, including acetaminophen, significantly increases the risk of analgesic nephropathy, renal papillary necrosis, and end-stage renal disease. Additive hepatic toxicity may occur, especially in combined overdose situations. Do not exceed the recommended individual maximum doses when these agents are given concurrently for short-term therapy.
    Bisoprolol; Hydrochlorothiazide, HCTZ: (Moderate) Monitor for decreased diuretic efficacy and additive orthostatic hypotension when thiazide diuretics are administered with tramadol. Adjustments to diuretic therapy may be needed in some patients. The efficacy of diuretics may be reduced due to opioid-induced release of antidiuretic hormone.
    Boceprevir: (Moderate) Close clinical monitoring is advised when administering acetaminophen with boceprevir due to an increased potential for acetaminophen-related adverse events. If acetaminophen dose adjustments are made, re-adjust the dose upon completion of boceprevir treatment. Although this interaction has not been studied, predictions about the interaction can be made based on the metabolic pathway of acetaminophen. Acetaminophen is partially metabolized by the hepatic isoenzyme CYP3A4; boceprevir inhibits this isoenzyme. Coadministration may result in elevated acetaminophen plasma concentrations. (Moderate) Close clinical monitoring is advised when administering tramadol with boceprevir due to an increased potential for tramadol-related adverse events. If tramadol dose adjustments are made, re-adjust the dose upon completion of boceprevir treatment. Although this interaction has not been studied, predictions about the interaction can be made based on the metabolic pathway of tramadol. Tramadol is partially metabolized by the hepatic isoenzyme CYP3A4; boceprevir inhibits this isoenzyme. Coadministration may result in elevated tramadol plasma concentrations.
    Brexpiprazole: (Major) Concomitant use of tramadol with brexpiprazole may cause excessive sedation, somnolence, and increased risk of seizures. Limit the use of opioid pain medications with brexpiprazole to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. Educate patients about the risks and symptoms of excessive CNS depression and seizures.
    Brigatinib: (Moderate) Monitor for reduced efficacy of tramadol and signs of opioid withdrawal if coadministration with brigatinib is necessary; consider increasing the dose of tramadol as needed. If brigatinib is discontinued, consider a dose reduction of tramadol and frequently monitor for seizures, serotonin syndrome, and signs of respiratory depression and sedation. Tramadol is a CYP3A4 substrate and brigatinib is a weak CYP3A4 inducer. Concomitant use with CYP3A4 inducers can decrease tramadol levels; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence.
    Brimonidine: (Moderate) Based on the sedative effects of brimonidine in individual patients, brimonidine administration has potential to enhance the CNS depressants effects of opiate agonists.
    Brimonidine; Brinzolamide: (Moderate) Based on the sedative effects of brimonidine in individual patients, brimonidine administration has potential to enhance the CNS depressants effects of opiate agonists.
    Brimonidine; Timolol: (Moderate) Based on the sedative effects of brimonidine in individual patients, brimonidine administration has potential to enhance the CNS depressants effects of opiate agonists.
    Brompheniramine: (Moderate) Concomitant use of opioid agonists with brompheniramine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with brompheniramine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Brompheniramine; Carbetapentane; Phenylephrine: (Moderate) Concomitant use of opioid agonists with brompheniramine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with brompheniramine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. (Moderate) Drowsiness has been reported during administration of carbetapentane. An enhanced CNS depressant effect may occur when carbetapentane is combined with other CNS depressants including morphine.
    Brompheniramine; Dextromethorphan; Guaifenesin: (Moderate) Concomitant use of opioid agonists with brompheniramine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with brompheniramine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Brompheniramine; Dextromethorphan; Phenylephrine: (Moderate) Concomitant use of opioid agonists with brompheniramine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with brompheniramine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Brompheniramine; Guaifenesin; Hydrocodone: (Major) Concomitant use of tramadol increases the seizure risk in patients taking opiate agonists. Also, tramadol can cause additive CNS depression and respiratory depression when used with opiate agonists; avoid concurrent use whenever possible. If used together, extreme caution is needed, and a reduced tramadol dose is recommended. (Moderate) Concomitant use of opioid agonists with brompheniramine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with brompheniramine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Brompheniramine; Hydrocodone; Pseudoephedrine: (Major) Concomitant use of tramadol increases the seizure risk in patients taking opiate agonists. Also, tramadol can cause additive CNS depression and respiratory depression when used with opiate agonists; avoid concurrent use whenever possible. If used together, extreme caution is needed, and a reduced tramadol dose is recommended. (Moderate) Concomitant use of opioid agonists with brompheniramine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with brompheniramine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Brompheniramine; Phenylephrine: (Moderate) Concomitant use of opioid agonists with brompheniramine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with brompheniramine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Brompheniramine; Pseudoephedrine: (Moderate) Concomitant use of opioid agonists with brompheniramine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with brompheniramine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Brompheniramine; Pseudoephedrine; Dextromethorphan: (Moderate) Concomitant use of opioid agonists with brompheniramine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with brompheniramine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Budesonide; Glycopyrrolate; Formoterol: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when tramadol is used concomitantly with an anticholinergic drug. The concomitant use of tramadol and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Bumetanide: (Moderate) Monitor for decreased diuretic efficacy and additive orthostatic hypotension when loop diuretics are administered with tramadol. Adjustments to diuretic therapy may be needed in some patients. The efficacy of diuretics may be reduced due to opioid-induced release of antidiuretic hormone.
    Bupivacaine Liposomal: (Moderate) Coadministration of bupivacaine with oxidizing agents, such as acetaminophen, may increase the risk of developing methemoglobinemia. Monitor patients closely for signs and symptoms of methemoglobinemia if coadministration is necessary. If methemoglobinemia occurs or is suspected, discontinue bupivacaine and any other oxidizing agents. Depending on the severity of symptoms, patients may respond to supportive care; more severe symptoms may require treatment with methylene blue, exchange transfusion, or hyperbaric oxygen.
    Bupivacaine: (Moderate) Coadministration of bupivacaine with oxidizing agents, such as acetaminophen, may increase the risk of developing methemoglobinemia. Monitor patients closely for signs and symptoms of methemoglobinemia if coadministration is necessary. If methemoglobinemia occurs or is suspected, discontinue bupivacaine and any other oxidizing agents. Depending on the severity of symptoms, patients may respond to supportive care; more severe symptoms may require treatment with methylene blue, exchange transfusion, or hyperbaric oxygen.
    Bupivacaine; Lidocaine: (Moderate) Coadministration of bupivacaine with oxidizing agents, such as acetaminophen, may increase the risk of developing methemoglobinemia. Monitor patients closely for signs and symptoms of methemoglobinemia if coadministration is necessary. If methemoglobinemia occurs or is suspected, discontinue bupivacaine and any other oxidizing agents. Depending on the severity of symptoms, patients may respond to supportive care; more severe symptoms may require treatment with methylene blue, exchange transfusion, or hyperbaric oxygen. (Moderate) Coadministration of lidocaine with oxidizing agents, such as acetaminophen, may increase the risk of developing methemoglobinemia. Monitor patients closely for signs and symptoms of methemoglobinemia if coadministration is necessary. If methemoglobinemia occurs or is suspected, discontinue lidocaine and any other oxidizing agents. Depending on the severity of symptoms, patients may respond to supportive care; more severe symptoms may require treatment with methylene blue, exchange transfusion, or hyperbaric oxygen.
    Bupivacaine; Meloxicam: (Moderate) Coadministration of bupivacaine with oxidizing agents, such as acetaminophen, may increase the risk of developing methemoglobinemia. Monitor patients closely for signs and symptoms of methemoglobinemia if coadministration is necessary. If methemoglobinemia occurs or is suspected, discontinue bupivacaine and any other oxidizing agents. Depending on the severity of symptoms, patients may respond to supportive care; more severe symptoms may require treatment with methylene blue, exchange transfusion, or hyperbaric oxygen.
    Buprenorphine: (Major) Buprenorphine is a mixed opiate agonist/antagonist with strong affinity for the mu-receptor that may partially block the effects of full mu-receptor opiate agonists and reduce analgesic effects. In some cases of acute pain, trauma, or during surgical management, opiate-dependent patients receiving buprenorphine maintenance therapy may require concurrent treatment with opiate agonists, such as tramadol. In these cases, health care professionals must exercise caution in opiate agonist dose selection, as higher doses of an opiate agonist may be required to compete with buprenorphine at the mu-receptor. Management strategies may include adding a short-acting opiate agonist to achieve analgesia in the presence of buprenorphine, discontinuation of buprenorphine and use of an opiate agonist to avoid withdrawal and achieve analgesia, or conversion of buprenorphine to methadone while using additional opiate agonists if needed. Closely monitor patients for CNS or respiratory depression. When buprenorphine is used for analgesia, avoid co-use with opiate agonists. Buprenorphine may cause withdrawal symptoms in patients receiving chronic opiate agonists as well as possibly potentiate CNS, respiratory, and hypotensive effects. The additive or antagonistic effects are dependent upon the dose of the opiate agonist used; antagonistic effects are more common at low to moderate doses of the opiate agonist. Additionally, concurrent use of opiates with other drugs that modulate serotonergic function, such as tramadol, has resulted in serotonin syndrome in some cases. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. If combination treatment is required, patients should be carefully observed, particularly during treatment initiation and during dose adjustments of the serotonergic drug; discontinue buprenorphine if serotonin syndrome is suspected. Consider a dose reduction of one or both drugs because of the potential for additive pharmacological effects. There is also a potential for increased risk of seizures if tramadol is given with other opiates.
    Buprenorphine; Naloxone: (Major) Buprenorphine is a mixed opiate agonist/antagonist with strong affinity for the mu-receptor that may partially block the effects of full mu-receptor opiate agonists and reduce analgesic effects. In some cases of acute pain, trauma, or during surgical management, opiate-dependent patients receiving buprenorphine maintenance therapy may require concurrent treatment with opiate agonists, such as tramadol. In these cases, health care professionals must exercise caution in opiate agonist dose selection, as higher doses of an opiate agonist may be required to compete with buprenorphine at the mu-receptor. Management strategies may include adding a short-acting opiate agonist to achieve analgesia in the presence of buprenorphine, discontinuation of buprenorphine and use of an opiate agonist to avoid withdrawal and achieve analgesia, or conversion of buprenorphine to methadone while using additional opiate agonists if needed. Closely monitor patients for CNS or respiratory depression. When buprenorphine is used for analgesia, avoid co-use with opiate agonists. Buprenorphine may cause withdrawal symptoms in patients receiving chronic opiate agonists as well as possibly potentiate CNS, respiratory, and hypotensive effects. The additive or antagonistic effects are dependent upon the dose of the opiate agonist used; antagonistic effects are more common at low to moderate doses of the opiate agonist. Additionally, concurrent use of opiates with other drugs that modulate serotonergic function, such as tramadol, has resulted in serotonin syndrome in some cases. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. If combination treatment is required, patients should be carefully observed, particularly during treatment initiation and during dose adjustments of the serotonergic drug; discontinue buprenorphine if serotonin syndrome is suspected. Consider a dose reduction of one or both drugs because of the potential for additive pharmacological effects. There is also a potential for increased risk of seizures if tramadol is given with other opiates.
    Bupropion: (Major) Increased serum concentrations of tramadol and reduced serum concentrations of the O-desmethyltramadol metabolite (M1) would be expected from concurrent use of tramadol and a CYP2D6 inhibitor such as bupropion. As the analgesic activity of tramadol is due to both the parent drug and M1, inhibition of CYP2D6 by bupropion may affect the analgesic effect of tramadol; reduced analgesic effects are possible. Also, administration of tramadol may enhance the seizure risk in patients taking other medications that decrease the seizure threshold such as bupropion.
    Bupropion; Naltrexone: (Major) Increased serum concentrations of tramadol and reduced serum concentrations of the O-desmethyltramadol metabolite (M1) would be expected from concurrent use of tramadol and a CYP2D6 inhibitor such as bupropion. As the analgesic activity of tramadol is due to both the parent drug and M1, inhibition of CYP2D6 by bupropion may affect the analgesic effect of tramadol; reduced analgesic effects are possible. Also, administration of tramadol may enhance the seizure risk in patients taking other medications that decrease the seizure threshold such as bupropion.
    Buspirone: (Moderate) Tramadol can cause additive CNS depression when used with other agents that are CNS depressants including buspirone.
    Busulfan: (Moderate) Use busulfan and acetaminophen together with caution; concomitant use may result in increased busulfan levels and increased busulfan toxicity. Separating the administration of these drugs may mitigate this interaction; avoid giving acetaminophen within 72 hours prior to or concurrently with busulfan. Busulfan is metabolized in the liver through conjugation with glutathione; acetaminophen decreases glutathione levels in the blood and tissues and may reduce the clearance of busulfan.
    Butabarbital: (Major) Concomitant use of tramadol with barbiturates may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medications with barbiturates to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation. Additionally, concomitant use of tramadol with a barbiturate can decrease tramadol concentrations; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence. Monitor for reduced efficacy of tramadol and signs of opioid withdrawal. Discontinuation of a barbiturate may increase the risk of seizures, serotonin syndrome, and the risk of opioid-related adverse reactions, such as fatal respiratory depression. Barbiturates induce CYP3A4; tramadol is a CYP3A4 substrate. (Minor) Chronic therapy with barbiturates can increase the metabolism and decrease the effectiveness of acetaminophen. During acute overdoses, barbiturates can enhance the formation of toxic acetaminophen metabolites.
    Butalbital; Acetaminophen: (Major) Concomitant use of tramadol with barbiturates may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medications with barbiturates to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation. Additionally, concomitant use of tramadol with a barbiturate can decrease tramadol concentrations; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence. Monitor for reduced efficacy of tramadol and signs of opioid withdrawal. Discontinuation of a barbiturate may increase the risk of seizures, serotonin syndrome, and the risk of opioid-related adverse reactions, such as fatal respiratory depression. Barbiturates induce CYP3A4; tramadol is a CYP3A4 substrate. (Minor) Chronic therapy with barbiturates can increase the metabolism and decrease the effectiveness of acetaminophen. During acute overdoses, barbiturates can enhance the formation of toxic acetaminophen metabolites.
    Butalbital; Acetaminophen; Caffeine: (Major) Concomitant use of tramadol with barbiturates may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medications with barbiturates to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation. Additionally, concomitant use of tramadol with a barbiturate can decrease tramadol concentrations; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence. Monitor for reduced efficacy of tramadol and signs of opioid withdrawal. Discontinuation of a barbiturate may increase the risk of seizures, serotonin syndrome, and the risk of opioid-related adverse reactions, such as fatal respiratory depression. Barbiturates induce CYP3A4; tramadol is a CYP3A4 substrate. (Minor) Chronic therapy with barbiturates can increase the metabolism and decrease the effectiveness of acetaminophen. During acute overdoses, barbiturates can enhance the formation of toxic acetaminophen metabolites.
    Butalbital; Acetaminophen; Caffeine; Codeine: (Major) Concomitant use of tramadol increases the seizure risk in patients taking opiate agonists. Also, tramadol can cause additive CNS depression and respiratory depression when used with opiate agonists; avoid concurrent use whenever possible. If used together, extreme caution is needed, and a reduced tramadol dose is recommended. (Major) Concomitant use of tramadol with barbiturates may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medications with barbiturates to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation. Additionally, concomitant use of tramadol with a barbiturate can decrease tramadol concentrations; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence. Monitor for reduced efficacy of tramadol and signs of opioid withdrawal. Discontinuation of a barbiturate may increase the risk of seizures, serotonin syndrome, and the risk of opioid-related adverse reactions, such as fatal respiratory depression. Barbiturates induce CYP3A4; tramadol is a CYP3A4 substrate. (Minor) Chronic therapy with barbiturates can increase the metabolism and decrease the effectiveness of acetaminophen. During acute overdoses, barbiturates can enhance the formation of toxic acetaminophen metabolites.
    Butorphanol: (Major) Avoid the concomitant use of butorphanol and opiate agonists, such as tramadol. Butorphanol is a mixed opiate agonist/antagonist that may block the effects of opiate agonists and reduce analgesic effects. Butorphanol may cause withdrawal symptoms in patients receiving chronic opiate agonists. Concurrent use of butorphanol with other opiate agonists can cause additive CNS, respiratory, and hypotensive effects. The additive or antagonistic effects are dependent upon the dose of the opiate agonist used; antagonistic effects are more common at low to moderate doses of the opiate agonist. There is also a potential increased risk of seizures if tramadol is given with other opiates.
    Calcium, Magnesium, Potassium, Sodium Oxybates: (Major) Concomitant use of opioid agonists with sodium oxybate may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medication with sodium oxybate to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Also monitor patients for the emergence of serotonin syndrome. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. The concomitant use of opioids with other drugs that affect the serotonergic neurotransmitter system has resulted in serotonin syndrome.
    Candesartan; Hydrochlorothiazide, HCTZ: (Moderate) Monitor for decreased diuretic efficacy and additive orthostatic hypotension when thiazide diuretics are administered with tramadol. Adjustments to diuretic therapy may be needed in some patients. The efficacy of diuretics may be reduced due to opioid-induced release of antidiuretic hormone.
    Cannabidiol: (Moderate) Concomitant use of opioid agonists with cannabidiol may cause excessive sedation and somnolence. Limit the use of opioid pain medications with cannabidiol to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. Educate patients about the risks and symptoms of excessive CNS depression.
    Capsaicin; Metaxalone: (Major) Concomitant use of opioid agonists with metaxalone may cause excessive sedation and somnolence. Limit the use of opioid pain medications with metaxalone to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. If concomitant use of tramadol and metaxalone is warranted, monitor patients for the emergence of serotonin syndrome. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. The concomitant use of opioids with other drugs that affect the serotonergic neurotransmitter system has resulted in serotonin syndrome.
    Captopril; Hydrochlorothiazide, HCTZ: (Moderate) Monitor for decreased diuretic efficacy and additive orthostatic hypotension when thiazide diuretics are administered with tramadol. Adjustments to diuretic therapy may be needed in some patients. The efficacy of diuretics may be reduced due to opioid-induced release of antidiuretic hormone.
    Carbamazepine: (Moderate) Monitor for reduced efficacy of tramadol and signs of opioid withdrawal if coadministration with carbamazepine is necessary; consider increasing the dose of tramadol as needed. If carbamazepine is discontinued, consider a dose reduction of tramadol and frequently monitor for seizures, serotonin syndrome, and signs of respiratory depression and sedation. Tramadol is a CYP3A4 substrate and carbamazepine is a strong CYP3A4 inducer. Concomitant use with CYP3A4 inducers can decrease tramadol levels; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence. (Minor) Carbamazepine may potentially accelerate the hepatic metabolism of acetaminophen. In addition, due to enzyme induction, carbamazepine may increase the risk for acetaminophen-induced hepatotoxicity via generation of a greater percentage of acetaminophen's hepatotoxic metabolite, NAPQI. Clinicians should be alert to decreased effect of acetaminophen. Dosage adjustments may be necessary, and closer monitoring of clinical and/or adverse effects is warranted.
    Carbetapentane; Chlorpheniramine: (Moderate) Concomitant use of opioid agonists with chlorpheniramine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with chlorpheniramine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. (Moderate) Drowsiness has been reported during administration of carbetapentane. An enhanced CNS depressant effect may occur when carbetapentane is combined with other CNS depressants including morphine.
    Carbetapentane; Chlorpheniramine; Phenylephrine: (Moderate) Concomitant use of opioid agonists with chlorpheniramine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with chlorpheniramine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. (Moderate) Drowsiness has been reported during administration of carbetapentane. An enhanced CNS depressant effect may occur when carbetapentane is combined with other CNS depressants including morphine.
    Carbetapentane; Diphenhydramine; Phenylephrine: (Moderate) Concomitant use of opioid agonists with diphenhydramine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with diphenhydramine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. (Moderate) Drowsiness has been reported during administration of carbetapentane. An enhanced CNS depressant effect may occur when carbetapentane is combined with other CNS depressants including morphine.
    Carbetapentane; Guaifenesin: (Moderate) Drowsiness has been reported during administration of carbetapentane. An enhanced CNS depressant effect may occur when carbetapentane is combined with other CNS depressants including morphine.
    Carbetapentane; Guaifenesin; Phenylephrine: (Moderate) Drowsiness has been reported during administration of carbetapentane. An enhanced CNS depressant effect may occur when carbetapentane is combined with other CNS depressants including morphine.
    Carbetapentane; Phenylephrine: (Moderate) Drowsiness has been reported during administration of carbetapentane. An enhanced CNS depressant effect may occur when carbetapentane is combined with other CNS depressants including morphine.
    Carbetapentane; Phenylephrine; Pyrilamine: (Moderate) Concomitant use of opioid agonists with pyrilamine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with pyrilamine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. (Moderate) Drowsiness has been reported during administration of carbetapentane. An enhanced CNS depressant effect may occur when carbetapentane is combined with other CNS depressants including morphine.
    Carbetapentane; Pseudoephedrine: (Moderate) Drowsiness has been reported during administration of carbetapentane. An enhanced CNS depressant effect may occur when carbetapentane is combined with other CNS depressants including morphine.
    Carbetapentane; Pyrilamine: (Moderate) Concomitant use of opioid agonists with pyrilamine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with pyrilamine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. (Moderate) Drowsiness has been reported during administration of carbetapentane. An enhanced CNS depressant effect may occur when carbetapentane is combined with other CNS depressants including morphine.
    Carbinoxamine: (Moderate) Concomitant use of opioid agonists with carbinoxamine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with carbinoxamine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Carbinoxamine; Dextromethorphan; Pseudoephedrine: (Moderate) Concomitant use of opioid agonists with carbinoxamine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with carbinoxamine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Carbinoxamine; Hydrocodone; Phenylephrine: (Major) Concomitant use of tramadol increases the seizure risk in patients taking opiate agonists. Also, tramadol can cause additive CNS depression and respiratory depression when used with opiate agonists; avoid concurrent use whenever possible. If used together, extreme caution is needed, and a reduced tramadol dose is recommended. (Moderate) Concomitant use of opioid agonists with carbinoxamine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with carbinoxamine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Carbinoxamine; Hydrocodone; Pseudoephedrine: (Major) Concomitant use of tramadol increases the seizure risk in patients taking opiate agonists. Also, tramadol can cause additive CNS depression and respiratory depression when used with opiate agonists; avoid concurrent use whenever possible. If used together, extreme caution is needed, and a reduced tramadol dose is recommended. (Moderate) Concomitant use of opioid agonists with carbinoxamine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with carbinoxamine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Carbinoxamine; Phenylephrine: (Moderate) Concomitant use of opioid agonists with carbinoxamine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with carbinoxamine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Carbinoxamine; Pseudoephedrine: (Moderate) Concomitant use of opioid agonists with carbinoxamine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with carbinoxamine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Cariprazine: (Moderate) Concomitant use of opioid agonists with cariprazine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with cariprazine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. Also, concomitant use of tramadol increases the seizure risk in patients taking cariprazine.
    Carisoprodol: (Major) Concomitant use of tramadol with a skeletal muscle relaxant may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medications with a skeletal muscle relaxant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Celecoxib: (Moderate) Monitor for reduced efficacy of tramadol and signs of opioid withdrawal if coadministration with celecoxib is necessary; also monitor for tramadol-related adverse reactions, including seizures and serotonin syndrome. Consider increasing the dose of tramadol if clinically appropriate. If celecoxib is discontinued, consider a dose reduction of tramadol and frequently monitor for signs or respiratory depression and sedation. Tramadol is metabolized by CYP2D6 to its active metabolite, M1; M1 is critical to the activity of tramadol. Celecoxib is a CYP2D6 inhibitor. Concomitant use with CYP2D6 inhibitors may result in an increase in tramadol plasma concentrations and a decrease in the concentrations of the active metabolite, M1. In patients who have developed physical dependence to tramadol, decreased M1 concentrations may result in opioid withdrawal or reduced efficacy while increased tramadol concentrations may cause serotonin syndrome or seizures.
    Cenobamate: (Moderate) Concomitant use of tramadol with cenobamate may cause excessive sedation and somnolence. Limit the use of tramadol with cenobamate to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. Educate patients about the risks and symptoms of excessive CNS depression. Additionally, monitor for reduced efficacy of tramadol and signs of opioid withdrawal if coadministration with cenobamate is necessary; consider increasing the dose of tramadol as needed. If cenobamate is discontinued, consider a dose reduction of tramadol and frequently monitor for seizures, serotonin syndrome, and signs of respiratory depression and sedation. Tramadol is a CYP3A4 substrate and cenobamate is a moderate CYP3A4 inducer. Concomitant use with CYP3A4 inducers can decrease tramadol concentrations; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence.
    Ceritinib: (Moderate) Consider a tramadol dosage reduction until stable drug effects are achieved if coadministration with ceritinib is necessary. Closely monitor for seizures, serotonin syndrome, and signs of sedation and respiratory depression. Respiratory depression from increased tramadol exposure may be fatal. Concurrent use of ceritinib, a strong CYP3A4 inhibitor, may increase tramadol exposure and result in greater CYP2D6 metabolism thereby increasing exposure to the active metabolite M1, which is a more potent mu-opioid agonist.
    Cetirizine: (Moderate) Concomitant use of opioid agonists with cetirizine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with cetirizine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Cetirizine; Pseudoephedrine: (Moderate) Concomitant use of opioid agonists with cetirizine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with cetirizine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Charcoal: (Minor) Activated charcoal binds many drugs within the gut. Administering charcoal dietary supplements at the same time as a routine acetaminophen dosage would be expected to interfere with the analgesic and antipyretic efficacy of acetaminophen. Charcoal is mostly used in the setting of acetaminophen overdose; however, patients should never try to treat an acetaminophen overdose with charcoal dietary supplements. Advise patients to get immediate medical attention for an acetaminophen overdose.
    Chlophedianol; Dexbrompheniramine: (Moderate) Concomitant use of opioid agonists with dexbrompheniramine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with dexbrompheniramine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Chlophedianol; Dexchlorpheniramine; Pseudoephedrine: (Moderate) Concomitant use of opioid agonists with dexchlorpheniramine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with dexchlorpheniramine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Chloral Hydrate: (Major) Concomitant use of opioid agonists with chloral hydrate may cause excessive sedation and somnolence. Limit the use of opioid pain medications with chloral hydrate to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. Educate patients about the risks and symptoms of excessive CNS depression.
    Chlorcyclizine: (Moderate) Concomitant use of opioid agonists with chlorcyclizine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with chlorcyclizine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Chlordiazepoxide: (Major) Concomitant use of opiate agonists with benzodiazepines may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opiate pain medications with benzodiazepines to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If an opiate agonist is initiated in a patient taking a benzodiazepine, use a lower initial dose of the opiate and titrate to clinical response. If a benzodiazepine is prescribed for an indication other than epilepsy in a patient taking an opiate agonist, use a lower initial dose of the benzodiazepine and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Chlordiazepoxide; Amitriptyline: (Major) Concomitant use of opiate agonists with benzodiazepines may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opiate pain medications with benzodiazepines to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If an opiate agonist is initiated in a patient taking a benzodiazepine, use a lower initial dose of the opiate and titrate to clinical response. If a benzodiazepine is prescribed for an indication other than epilepsy in a patient taking an opiate agonist, use a lower initial dose of the benzodiazepine and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Chlordiazepoxide; Clidinium: (Major) Concomitant use of opiate agonists with benzodiazepines may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opiate pain medications with benzodiazepines to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If an opiate agonist is initiated in a patient taking a benzodiazepine, use a lower initial dose of the opiate and titrate to clinical response. If a benzodiazepine is prescribed for an indication other than epilepsy in a patient taking an opiate agonist, use a lower initial dose of the benzodiazepine and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation. (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when tramadol is used concomitantly with an anticholinergic drug. The concomitant use of tramadol and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Chloroprocaine: (Moderate) Coadministration of chloroprocaine with oxidizing agents, such as acetaminophen, may increase the risk of developing methemoglobinemia. Monitor patients closely for signs and symptoms of methemoglobinemia if coadministration is necessary. If methemoglobinemia occurs or is suspected, discontinue chloroprocaine and any other oxidizing agents. Depending on the severity of symptoms, patients may respond to supportive care; more severe symptoms may require treatment with methylene blue, exchange transfusion, or hyperbaric oxygen.
    Chlorothiazide: (Moderate) Monitor for decreased diuretic efficacy and additive orthostatic hypotension when thiazide diuretics are administered with tramadol. Adjustments to diuretic therapy may be needed in some patients. The efficacy of diuretics may be reduced due to opioid-induced release of antidiuretic hormone.
    Chlorpheniramine: (Moderate) Concomitant use of opioid agonists with chlorpheniramine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with chlorpheniramine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Chlorpheniramine; Codeine: (Major) Concomitant use of tramadol increases the seizure risk in patients taking opiate agonists. Also, tramadol can cause additive CNS depression and respiratory depression when used with opiate agonists; avoid concurrent use whenever possible. If used together, extreme caution is needed, and a reduced tramadol dose is recommended. (Moderate) Concomitant use of opioid agonists with chlorpheniramine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with chlorpheniramine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Chlorpheniramine; Dextromethorphan: (Moderate) Concomitant use of opioid agonists with chlorpheniramine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with chlorpheniramine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Chlorpheniramine; Dextromethorphan; Phenylephrine: (Moderate) Concomitant use of opioid agonists with chlorpheniramine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with chlorpheniramine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Chlorpheniramine; Dextromethorphan; Pseudoephedrine: (Moderate) Concomitant use of opioid agonists with chlorpheniramine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with chlorpheniramine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Chlorpheniramine; Dihydrocodeine; Phenylephrine: (Major) Concomitant use of tramadol increases the seizure risk in patients taking opiate agonists. Also, tramadol can cause additive CNS depression and respiratory depression when used with opiate agonists; avoid concurrent use whenever possible. If used together, extreme caution is needed, and a reduced tramadol dose is recommended. (Moderate) Concomitant use of opioid agonists with chlorpheniramine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with chlorpheniramine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Chlorpheniramine; Dihydrocodeine; Pseudoephedrine: (Major) Concomitant use of tramadol increases the seizure risk in patients taking opiate agonists. Also, tramadol can cause additive CNS depression and respiratory depression when used with opiate agonists; avoid concurrent use whenever possible. If used together, extreme caution is needed, and a reduced tramadol dose is recommended. (Moderate) Concomitant use of opioid agonists with chlorpheniramine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with chlorpheniramine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Chlorpheniramine; Guaifenesin; Hydrocodone; Pseudoephedrine: (Major) Concomitant use of tramadol increases the seizure risk in patients taking opiate agonists. Also, tramadol can cause additive CNS depression and respiratory depression when used with opiate agonists; avoid concurrent use whenever possible. If used together, extreme caution is needed, and a reduced tramadol dose is recommended. (Moderate) Concomitant use of opioid agonists with chlorpheniramine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with chlorpheniramine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Chlorpheniramine; Hydrocodone: (Major) Concomitant use of tramadol increases the seizure risk in patients taking opiate agonists. Also, tramadol can cause additive CNS depression and respiratory depression when used with opiate agonists; avoid concurrent use whenever possible. If used together, extreme caution is needed, and a reduced tramadol dose is recommended. (Moderate) Concomitant use of opioid agonists with chlorpheniramine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with chlorpheniramine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Chlorpheniramine; Hydrocodone; Phenylephrine: (Major) Concomitant use of tramadol increases the seizure risk in patients taking opiate agonists. Also, tramadol can cause additive CNS depression and respiratory depression when used with opiate agonists; avoid concurrent use whenever possible. If used together, extreme caution is needed, and a reduced tramadol dose is recommended. (Moderate) Concomitant use of opioid agonists with chlorpheniramine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with chlorpheniramine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Chlorpheniramine; Hydrocodone; Pseudoephedrine: (Major) Concomitant use of tramadol increases the seizure risk in patients taking opiate agonists. Also, tramadol can cause additive CNS depression and respiratory depression when used with opiate agonists; avoid concurrent use whenever possible. If used together, extreme caution is needed, and a reduced tramadol dose is recommended. (Moderate) Concomitant use of opioid agonists with chlorpheniramine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with chlorpheniramine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Chlorpheniramine; Ibuprofen; Pseudoephedrine: (Moderate) Concomitant use of opioid agonists with chlorpheniramine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with chlorpheniramine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Chlorpheniramine; Phenylephrine: (Moderate) Concomitant use of opioid agonists with chlorpheniramine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with chlorpheniramine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Chlorpheniramine; Pseudoephedrine: (Moderate) Concomitant use of opioid agonists with chlorpheniramine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with chlorpheniramine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Chlorpromazine: (Moderate) Concurrent use of tramadol and chlorpromazine should be avoided if possible. Antipsychotics may enhance the seizure risk of tramadol. In addition, in vitro data suggest that chlorpromazine has CYP2D6 inhibitory effects and has the potential to decrease the metabolism of CYP2D6 substrates such as tramadol. Although the full pharmacologic impact of increased tramadol exposure is unknown, close monitoring for serious adverse effects, such as seizures, is advisable. In addition, serotonin syndrome may occur during use of tramadol with medications that impair its metabolism. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, hyperreflexia, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Because the analgesic activity of tramadol is due to the activity of both the parent drug and the O-desmethyltramadol metabolite (M1), CYP2D6 inhibition by chlorpromazine may alter the analgesic response to tramadol. Additive CNS depression may also be seen with the concomitant use of tramadol and chlorpromazine.
    Chlorthalidone: (Moderate) Monitor for decreased diuretic efficacy and additive orthostatic hypotension when thiazide diuretics are administered with tramadol. Adjustments to diuretic therapy may be needed in some patients. The efficacy of diuretics may be reduced due to opioid-induced release of antidiuretic hormone.
    Chlorthalidone; Clonidine: (Major) Concomitant use of opioid agonists with clonidine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with clonidine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. (Moderate) Monitor for decreased diuretic efficacy and additive orthostatic hypotension when thiazide diuretics are administered with tramadol. Adjustments to diuretic therapy may be needed in some patients. The efficacy of diuretics may be reduced due to opioid-induced release of antidiuretic hormone.
    Chlorzoxazone: (Major) Concomitant use of tramadol with a skeletal muscle relaxant may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medications with a skeletal muscle relaxant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Cholestyramine: (Moderate) Cholestyramine has been shown to decrease the absorption of acetaminophen by roughly 60%. Experts have recommended that cholestyramine not be given within 1 hour of acetaminophen if analgesic or antipyretic effect is to be achieved.
    Choline Salicylate; Magnesium Salicylate: (Moderate) Prolonged concurrent use of acetaminophen and salicylates is not recommended. Although salicylates are rarely associated with nephrotoxicity, high-dose, chronic administration of salicylates combined other analgesics, including acetaminophen, significantly increases the risk of analgesic nephropathy, renal papillary necrosis, and end-stage renal disease. Additive hepatic toxicity may occur, especially in combined overdose situations. Do not exceed the recommended individual maximum doses when these agents are given concurrently for short-term therapy.
    Cinacalcet: (Moderate) Coadministration of cinacalcet, a strong CYP2D6 inhibitor, with tramadol, a CYP2D6 substrate, may decrease tramadol metabolism. This interaction may result in decreased tramadol efficacy and/or increased tramadol-induced risks of serotonin syndrome or seizures. The analgesic activity of tramadol is due to the activity of both the parent drug and the O-desmethyltramadol metabolite (M1), and M1 formation is dependent on CYP2D6. Therefore, use of tramadol with a CYP2D6-inhibitor may alter tramadol efficacy. In addition, inhibition of CYP2D6 metabolism is expected to result in reduced metabolic clearance of tramadol. This in turn may increase the risk of tramadol-related adverse events including serotonin syndrome and seizures. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death.
    Citalopram: (Moderate) Serotonin syndrome can occur during concomitant use of opiate agonists like tramadol with serotonergic drugs, such as citalopram. Several cases of serotonin syndrome have been reported after the administration of tramadol with an SSRI. Post-marketing reports implicate the concurrent use of SSRIs with tramadol in some cases of seizures. Lastly, citalopram is a weak inhibitor of CYP2D6. The analgesic activity of tramadol is due to the activity of both the parent drug and the O-desmethyltramadol metabolite (M1), and M1 formation is dependent on CYP2D6. Therefore, use of tramadol with a CYP2D6-inhibitor may alter tramadol efficacy. In addition, inhibition of CYP2D6 metabolism is expected to result in reduced metabolic clearance of tramadol. This in turn may increase the risk of tramadol-related adverse events including serotonin syndrome and seizures. If serotonin syndrome is suspected, citalopram and concurrent serotonergic agents should be discontinued.
    Clemastine: (Moderate) Concomitant use of opioid agonists with clemastine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with clemastine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Clobazam: (Major) Concomitant use of opiate agonists with benzodiazepines may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opiate pain medications with benzodiazepines to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If an opiate agonist is initiated in a patient taking a benzodiazepine, use a lower initial dose of the opiate and titrate to clinical response. If a benzodiazepine is prescribed for an indication other than epilepsy in a patient taking an opiate agonist, use a lower initial dose of the benzodiazepine and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation. Additionally, in vivo data suggest clobazam is a CYP2D6 inhibitor. Because the analgesic activity of tramadol is due to both the parent drug and O-desmethyltramadol (M1), inhibition of CYP2D6 by clobazam may affect the analgesic response to tramadol. Reduced analgesic effects of tramadol are possible, and the risk for serious adverse effects such as seizures may be increased.
    Clonazepam: (Major) Concomitant use of opiate agonists with benzodiazepines may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opiate pain medications with benzodiazepines to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If an opiate agonist is initiated in a patient taking a benzodiazepine, use a lower initial dose of the opiate and titrate to clinical response. If a benzodiazepine is prescribed for an indication other than epilepsy in a patient taking an opiate agonist, use a lower initial dose of the benzodiazepine and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Clonidine: (Major) Concomitant use of opioid agonists with clonidine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with clonidine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Clopidogrel: (Moderate) Coadministration of opioid agonists, such as tramadol, delay and reduce the absorption of clopidogrel resulting in reduced exposure to active metabolites and diminished inhibition of platelet aggregation. Consider the use of a parenteral antiplatelet agent in acute coronary syndrome patients requiring an opioid agonist. Coadministration of intravenous morphine decreased the Cmax and AUC of clopidogrel's active metabolites by 34%. Time required for maximal inhibition of platelet aggregation (median 3 hours vs. 1.25 hours) was significantly delayed; times up to 5 hours were reported. Inhibition of platelet plug formation was delayed and residual platelet aggregation was significantly greater 1 to 4 hours after morphine administration.
    Clorazepate: (Major) Concomitant use of opiate agonists with benzodiazepines may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opiate pain medications with benzodiazepines to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If an opiate agonist is initiated in a patient taking a benzodiazepine, use a lower initial dose of the opiate and titrate to clinical response. If a benzodiazepine is prescribed for an indication other than epilepsy in a patient taking an opiate agonist, use a lower initial dose of the benzodiazepine and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Clozapine: (Moderate) Concurrent use of tramadol and clozapine should be avoided if possible. Antipsychotics may enhance the seizure risk of tramadol. In addition, in vitro data suggest that clozapine has CYP2D6 inhibitory effects and may increase plasma concentrations of CYP2D6 substrates such as tramadol. Although the full pharmacologic impact of increased tramadol exposure is unknown, close monitoring for serious adverse effects, such as seizures, is advisable. In addition, serotonin syndrome may occur during use of tramadol with medications that impair its metabolism. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, hyperreflexia, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Because the analgesic activity of tramadol is due to the activity of both the parent drug and the O-desmethyltramadol metabolite (M1), CYP2D6 inhibition by clozapine may alter the analgesic response to tramadol. Additive CNS depression may also be seen with the concomitant use of tramadol and clozapine.
    Cobicistat: (Major) As cobicistat is a CYP2D6 and CYP3A4 inhibitor and tramadol is primarily metabolized by CYP2D6 and CYP3A4, concurrent therapy may decrease tramadol metabolism; reduced tramadol dose may be needed during coadministration. This interaction may result in decreased tramadol efficacy and/or increased tramadol-induced risks of serotonin syndrome or seizures. The analgesic activity of tramadol is due to the activity of both the parent drug and the O-desmethyltramadol metabolite (M1), and M1 formation is dependent on CYP2D6. Therefore, use of tramadol with a CYP2D6-inhibitor may alter tramadol efficacy. In addition, inhibition of either or both CYP2D6 and CYP3A4 is expected to result in reduced metabolic clearance of tramadol. This in turn may increase the risk of tramadol-related adverse events including serotonin syndrome and seizures. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death.
    Cocaine: (Major) Cocaine use has been associated with precipitating seizures. Since tramadol decreases the seizure threshold, an increased risk of seizures may be seen with concomitant use of these two drugs.
    Codeine: (Major) Concomitant use of tramadol increases the seizure risk in patients taking opiate agonists. Also, tramadol can cause additive CNS depression and respiratory depression when used with opiate agonists; avoid concurrent use whenever possible. If used together, extreme caution is needed, and a reduced tramadol dose is recommended.
    Codeine; Guaifenesin: (Major) Concomitant use of tramadol increases the seizure risk in patients taking opiate agonists. Also, tramadol can cause additive CNS depression and respiratory depression when used with opiate agonists; avoid concurrent use whenever possible. If used together, extreme caution is needed, and a reduced tramadol dose is recommended.
    Codeine; Guaifenesin; Pseudoephedrine: (Major) Concomitant use of tramadol increases the seizure risk in patients taking opiate agonists. Also, tramadol can cause additive CNS depression and respiratory depression when used with opiate agonists; avoid concurrent use whenever possible. If used together, extreme caution is needed, and a reduced tramadol dose is recommended.
    Codeine; Phenylephrine; Promethazine: (Major) Concomitant use of tramadol increases the seizure risk in patients taking opiate agonists. Also, tramadol can cause additive CNS depression and respiratory depression when used with opiate agonists; avoid concurrent use whenever possible. If used together, extreme caution is needed, and a reduced tramadol dose is recommended. (Moderate) Caution is advisable during concurrent use of tramadol and promethazine. Seizures have been reported in patients receiving monotherapy with both tramadol and promethazine at recommended doses. Concomitant use of tramadol and promethazine may increase the risk of seizures. In addition, due to the primary CNS effects of promethazine, caution is advisable during use of other centrally acting medications such as tramadol. Impairment of metabolism of tramadol by CYP2D6 inhibitors, such as promethazine, may increase the risk of serotonin syndrome. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. The analgesic activity of tramadol is due to the activity of both the parent drug and the O-desmethyltramadol metabolite (M1), and M1 formation is dependent on CYP2D6. Therefore, use of tramadol with a CYP2D6 inhibitor may decrease tramadol analgesic efficacy.
    Codeine; Promethazine: (Major) Concomitant use of tramadol increases the seizure risk in patients taking opiate agonists. Also, tramadol can cause additive CNS depression and respiratory depression when used with opiate agonists; avoid concurrent use whenever possible. If used together, extreme caution is needed, and a reduced tramadol dose is recommended. (Moderate) Caution is advisable during concurrent use of tramadol and promethazine. Seizures have been reported in patients receiving monotherapy with both tramadol and promethazine at recommended doses. Concomitant use of tramadol and promethazine may increase the risk of seizures. In addition, due to the primary CNS effects of promethazine, caution is advisable during use of other centrally acting medications such as tramadol. Impairment of metabolism of tramadol by CYP2D6 inhibitors, such as promethazine, may increase the risk of serotonin syndrome. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. The analgesic activity of tramadol is due to the activity of both the parent drug and the O-desmethyltramadol metabolite (M1), and M1 formation is dependent on CYP2D6. Therefore, use of tramadol with a CYP2D6 inhibitor may decrease tramadol analgesic efficacy.
    COMT inhibitors: (Major) Concomitant use of opioid agonists with COMT inhibitors may cause excessive sedation and somnolence. Limit the use of opioid pain medications with COMT inhibitors to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. Educate patients about the risks and symptoms of excessive CNS depression. COMT inhibitors have also been associated with sudden sleep onset during activities of daily living such as driving, which has resulted in accidents in some cases. Prescribers should re-assess patients for drowsiness or sleepiness regularly throughout treatment, especially since events may occur well after the start of treatment.
    Conivaptan: (Moderate) Consider a tramadol dosage reduction until stable drug effects are achieved if coadministration with conivaptan is necessary. Closely monitor for seizures, serotonin syndrome, and signs of sedation and respiratory depression. Respiratory depression from increased tramadol exposure may be fatal. Concurrent use of conivaptan, a moderate CYP3A inhibitor, may increase tramadol exposure and result in greater CYP2D6 metabolism thereby increasing exposure to the active metabolite M1, which is a more potent mu-opioid agonist.
    Crizotinib: (Moderate) Consider a tramadol dosage reduction until stable drug effects are achieved if coadministration with crizotinib is necessary. Closely monitor for seizures, serotonin syndrome, and signs of sedation and respiratory depression. Respiratory depression from increased tramadol exposure may be fatal. Concurrent use of crizotinib, a moderate CYP3A inhibitor, may increase tramadol exposure and result in greater CYP2D6 metabolism thereby increasing exposure to the active metabolite M1, which is a more potent mu-opioid agonist.
    Crofelemer: (Moderate) Pharmacodynamic interactions between crofelemer and opiate agonists are theoretically possible. Crofelemer does not affect GI motility mechanisms, but does have antidiarrheal effects. Patients taking medications that decrease GI motility, such as opiate agonists, may be at greater risk for serious complications from crofelemer, such as constipation with chronic use. Use caution and monitor GI symptoms during coadministration.
    Cyclizine: (Moderate) Concomitant use of opioid agonists with cyclizine may cause excessive sedation and somnolence. Limit the use of opioid pain medications with cyclizine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. Educate patients about the risks and symptoms of excessive CNS depression.
    Cyclobenzaprine: (Major) Concomitant use of tramadol with a skeletal muscle relaxant may cause respiratory depression, hypotension, profound sedation, and death. Additionally, concurrent use of tramadol and cyclobenzaprine increases the possibility of developing serotonin syndrome and enhances the risk of seizures in patients taking tramadol. Limit the use of opioid pain medications with a skeletal muscle relaxant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Closely monitor the patient for signs and symptoms of serotonin syndrome. Immediately discontinue concurrent use if serotonin syndrome occurs. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Cyproheptadine: (Moderate) Concomitant use of opioid agonists with cyproheptadine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with cyproheptadine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Dacomitinib: (Moderate) Coadministration of dacomitinib with tramadol may decrease tramadol metabolism resulting in decreased tramadol efficacy and/or increased tramadol-induced risks of serotonin syndrome or seizures. Tramadol is a CYP2D6 substrate; dacomitinib is a strong CYP2D6 inhibitor. The analgesic activity of tramadol is due to the activity of both the parent drug and the O-desmethyltramadol metabolite (M1), and M1 formation is dependent on CYP2D6. Therefore, use of tramadol with a CYP2D6-inhibitor may alter tramadol efficacy. In addition, inhibition of CYP2D6 metabolism is expected to result in reduced metabolic clearance of tramadol. This in turn may increase the risk of tramadol-related adverse events including serotonin syndrome and seizures. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death.
    Dantrolene: (Major) Concomitant use of tramadol with a skeletal muscle relaxant may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medications with a skeletal muscle relaxant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Dapsone: (Moderate) Coadministration of dapsone with acetaminophen may increase the risk of developing methemoglobinemia. Advise patients to discontinue treatment and seek immediate medical attention with any signs or symptoms of methemoglobinemia.
    Darifenacin: (Moderate) Coadministration of darifenacin with tramadol may decrease tramadol metabolism resulting in decreased tramadol efficacy and/or increased tramadol-induced risks for respiratory depression, serotonin syndrome, or seizures. Tramadol is a CYP2D6 substrate; darifenacin is a moderate CYP2D6 inhibitor. The analgesic activity of tramadol is due to the activity of both the parent drug and the O-desmethyltramadol metabolite (M1), and M1 formation is dependent on CYP2D6. Therefore, use of tramadol with a CYP2D6-inhibitor may alter tramadol efficacy. In addition, inhibition of CYP2D6 metabolism is expected to result in reduced metabolic clearance of tramadol that may increase the risk of tramadol-related adverse events including respiratory depression, serotonin syndrome, and seizures. In addition, the concomitant use of these drugs together may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates such as tramadol increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect. Both agents may also cause drowsiness or blurred vision, and patients should use care in driving or performing other hazardous tasks until the effects of the drugs are known.
    Darunavir: (Major) Concurrent use of tramadol with darunavir may decrease the CYP3A4 and CYP2D6 metabolism of tramadol; reduced tramadol dose may be needed during coadministration. This interaction may result in decreased tramadol efficacy and/or increased tramadol-induced risks of serotonin syndrome or seizures. The analgesic activity of tramadol is due to the activity of both the parent drug and the O-desmethyltramadol metabolite (M1), and M1 formation is dependent on CYP2D6. Therefore, use of tramadol with a CYP2D6-inhibitor may alter tramadol efficacy. In addition, inhibition of either or both CYP2D6 and CYP3A4 is expected to result in reduced metabolic clearance of tramadol. This in turn may increase the risk of tramadol-related adverse events including serotonin syndrome and seizures. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death.
    Darunavir; Cobicistat: (Major) As cobicistat is a CYP2D6 and CYP3A4 inhibitor and tramadol is primarily metabolized by CYP2D6 and CYP3A4, concurrent therapy may decrease tramadol metabolism; reduced tramadol dose may be needed during coadministration. This interaction may result in decreased tramadol efficacy and/or increased tramadol-induced risks of serotonin syndrome or seizures. The analgesic activity of tramadol is due to the activity of both the parent drug and the O-desmethyltramadol metabolite (M1), and M1 formation is dependent on CYP2D6. Therefore, use of tramadol with a CYP2D6-inhibitor may alter tramadol efficacy. In addition, inhibition of either or both CYP2D6 and CYP3A4 is expected to result in reduced metabolic clearance of tramadol. This in turn may increase the risk of tramadol-related adverse events including serotonin syndrome and seizures. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. (Major) Concurrent use of tramadol with darunavir may decrease the CYP3A4 and CYP2D6 metabolism of tramadol; reduced tramadol dose may be needed during coadministration. This interaction may result in decreased tramadol efficacy and/or increased tramadol-induced risks of serotonin syndrome or seizures. The analgesic activity of tramadol is due to the activity of both the parent drug and the O-desmethyltramadol metabolite (M1), and M1 formation is dependent on CYP2D6. Therefore, use of tramadol with a CYP2D6-inhibitor may alter tramadol efficacy. In addition, inhibition of either or both CYP2D6 and CYP3A4 is expected to result in reduced metabolic clearance of tramadol. This in turn may increase the risk of tramadol-related adverse events including serotonin syndrome and seizures. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death.
    Darunavir; Cobicistat; Emtricitabine; Tenofovir alafenamide: (Major) As cobicistat is a CYP2D6 and CYP3A4 inhibitor and tramadol is primarily metabolized by CYP2D6 and CYP3A4, concurrent therapy may decrease tramadol metabolism; reduced tramadol dose may be needed during coadministration. This interaction may result in decreased tramadol efficacy and/or increased tramadol-induced risks of serotonin syndrome or seizures. The analgesic activity of tramadol is due to the activity of both the parent drug and the O-desmethyltramadol metabolite (M1), and M1 formation is dependent on CYP2D6. Therefore, use of tramadol with a CYP2D6-inhibitor may alter tramadol efficacy. In addition, inhibition of either or both CYP2D6 and CYP3A4 is expected to result in reduced metabolic clearance of tramadol. This in turn may increase the risk of tramadol-related adverse events including serotonin syndrome and seizures. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. (Major) Concurrent use of tramadol with darunavir may decrease the CYP3A4 and CYP2D6 metabolism of tramadol; reduced tramadol dose may be needed during coadministration. This interaction may result in decreased tramadol efficacy and/or increased tramadol-induced risks of serotonin syndrome or seizures. The analgesic activity of tramadol is due to the activity of both the parent drug and the O-desmethyltramadol metabolite (M1), and M1 formation is dependent on CYP2D6. Therefore, use of tramadol with a CYP2D6-inhibitor may alter tramadol efficacy. In addition, inhibition of either or both CYP2D6 and CYP3A4 is expected to result in reduced metabolic clearance of tramadol. This in turn may increase the risk of tramadol-related adverse events including serotonin syndrome and seizures. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death.
    Dasabuvir; Ombitasvir; Paritaprevir; Ritonavir: (Major) Tramadol is primarily metabolized by CYP2D6 and CYP3A4; drugs that inhibit these enzymes, such as ritonavir, may decrease the metabolism of tramadol. This may result in a decreased concentration of the active metabolite (O-desmethyltramadol) leading to decreased analgesic effects and possibly increased side effects (seizures and serotonin syndrome) due to higher tramadol concentrations. (Moderate) Concurrent administration of acetaminophen with ritonavir may result in elevated acetaminophen plasma concentrations and subsequent adverse events. Acetaminophen is metabolized by the hepatic isoenzyme CYP3A4; ritonavir is an inhibitor of this enzyme. Caution and close monitoring are advised if these drugs are administered together.
    Delavirdine: (Moderate) Since tramadol is primarily metabolized by cytochrome P450 isoenzyme CYP2D6, agents that inhibit this enzyme, such as delavirdine, decrease the metabolism of tramadol. Concomitant use of these agents and tramadol may increase plasma levels of tramadol and decrease concentration of the active metabolite leading to decreased analgesic effects and possibly increased side effects due to higher tramadol concentrations.
    Desflurane: (Moderate) Concurrent use with opiate agonists can decrease the minimum alveolar concentration (MAC) of desflurane needed to produce anesthesia.
    Desmopressin: (Major) Additive hyponatremic effects may be seen in patients treated with desmopressin and drugs associated with water intoxication, hyponatremia, or SIADH including opiate agonists. Use combination with caution, and monitor patients for signs and symptoms of hyponatremia.
    Desogestrel; Ethinyl Estradiol: (Moderate) Acetaminophen may increase plasma ethinyl estradiol levels, possibly by inhibition of conjugation. Patients taking acetaminophen concomitantly may experience an increase in estrogen related side effects.
    Desvenlafaxine: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that have serotonergic properties such as tramadol. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. In one case, the addition of tramadol to extended-release venlafaxine (300 mg/day) and mirtazapine (30 mg/day) likely caused serotonin syndrome. A patient developed agitation, confusion, severe shivering, diaphoresis, myoclonus, hyperreflexia, mydriasis, tachycardia, and fever within 7 weeks of taking tramadol 400 mg daily. He had taken 300 mg tramadol without difficulty. Discontinuation of the 3 drugs and rehydration led to symptom resolution over 36 hours. Reinstitution of the antidepressants 3 days after patient presentation was uneventful. In addition, although clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 inhibition at doses of 100 mg/day, the manufacturer recommends that primary substrates of CYP2D6, such as tramadol, be dosed at the original level when coadministered with desvenlafaxine 100 mg or lower, or when desvenlafaxine is discontinued. The dose of these CYP2D6 substrates should be reduced by up to one-half if coadministered with desvenlafaxine 400 mg/day.
    Deutetrabenazine: (Major) Concomitant use of opiate agonists with deutetrabenazine may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opiate pain medications with deutetrabenazine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If an opiate agonist is initiated in a patient taking deutetrabenazine, use a lower initial dose of the opiate and titrate to clinical response. If deutetrabenazine is prescribed for a patient taking an opiate agonist, use a lower initial dose of deutetrabenazine and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Dexbrompheniramine: (Moderate) Concomitant use of opioid agonists with dexbrompheniramine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with dexbrompheniramine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Dexbrompheniramine; Pseudoephedrine: (Moderate) Concomitant use of opioid agonists with dexbrompheniramine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with dexbrompheniramine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Dexchlorpheniramine: (Moderate) Concomitant use of opioid agonists with dexchlorpheniramine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with dexchlorpheniramine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Dexchlorpheniramine; Dextromethorphan; Pseudoephedrine: (Moderate) Concomitant use of opioid agonists with dexchlorpheniramine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with dexchlorpheniramine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Dexmedetomidine: (Moderate) Concomitant use of opioid agonists with dexmedetomidine may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medication with dexmedetomidine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Dexpanthenol: (Moderate) Use caution when using dexpanthenol with drugs that decrease gastrointestinal motility, such as opiate agonists, as it may decrease the effectiveness of dexpanthenol.
    Dextromethorphan; Diphenhydramine; Phenylephrine: (Moderate) Concomitant use of opioid agonists with diphenhydramine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with diphenhydramine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Dextromethorphan; Quinidine: (Moderate) As quinidine is a potent inhibitor of CYP2D6 and tramadol is partially metabolized by CYP2D6, concurrent therapy may decrease tramadol metabolism. This interaction may result in decreased tramadol efficacy and/or increased tramadol-induced risks of serotonin syndrome or seizures. The analgesic activity of tramadol is due to the activity of both the parent drug and the O-desmethyltramadol metabolite (M1), and M1 formation is dependent on CYP2D6. Therefore, use of tramadol with a CYP2D6-inhibitor may alter tramadol efficacy. In addition, inhibition of CYP2D6 metabolism is expected to result in reduced metabolic clearance of tramadol. This in turn may increase the risk of tramadol-related adverse events including serotonin syndrome and seizures. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death.
    Diazepam: (Major) Concomitant use of opiate agonists with benzodiazepines may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opiate pain medications with benzodiazepines to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If an opiate agonist is initiated in a patient taking a benzodiazepine, use a lower initial dose of the opiate and titrate to clinical response. If parental diazepam is used with an opiate agonist, reduce the opiate agonist dosage by at least 1/3. If a benzodiazepine is prescribed for an indication other than epilepsy in a patient taking an opiate agonist, use a lower initial dose of the benzodiazepine and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Dicyclomine: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when tramadol is used concomitantly with an anticholinergic drug. The concomitant use of tramadol and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Diflunisal: (Moderate) Acetaminophen plasma concentrations can increase by approximately 50% following administration of diflunisal. Acetaminophen has no effect on diflunisal concentrations. Acetaminophen in high doses has been associated with severe hepatotoxic reactions; therefore, caution should be exercised when using these agents concomitantly.
    Digoxin: (Moderate) An increased incidence of digoxin toxicity has been reported in some patients during post-marketing reports with the concurrent use of tramadol and digoxin.
    Dihydrocodeine; Guaifenesin; Pseudoephedrine: (Major) Concomitant use of tramadol increases the seizure risk in patients taking opiate agonists. Also, tramadol can cause additive CNS depression and respiratory depression when used with opiate agonists; avoid concurrent use whenever possible. If used together, extreme caution is needed, and a reduced tramadol dose is recommended.
    Dimenhydrinate: (Moderate) Concomitant use of opioid agonists with dimenhydrinate may cause excessive sedation and somnolence. Limit the use of opioid pain medication with dimenhydrinate to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Diphenhydramine: (Moderate) Concomitant use of opioid agonists with diphenhydramine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with diphenhydramine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Diphenhydramine; Hydrocodone; Phenylephrine: (Major) Concomitant use of tramadol increases the seizure risk in patients taking opiate agonists. Also, tramadol can cause additive CNS depression and respiratory depression when used with opiate agonists; avoid concurrent use whenever possible. If used together, extreme caution is needed, and a reduced tramadol dose is recommended. (Moderate) Concomitant use of opioid agonists with diphenhydramine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with diphenhydramine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Diphenhydramine; Ibuprofen: (Moderate) Concomitant use of opioid agonists with diphenhydramine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with diphenhydramine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Diphenhydramine; Naproxen: (Moderate) Concomitant use of opioid agonists with diphenhydramine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with diphenhydramine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Diphenhydramine; Phenylephrine: (Moderate) Concomitant use of opioid agonists with diphenhydramine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with diphenhydramine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Diphenoxylate; Atropine: (Moderate) Concurrent administration of diphenoxylate/difenoxin with other opiate agonists can potentiate the CNS-depressant effects of diphenoxylate/difenoxin. Use caution during coadministration. In addition, diphenoxylate/difenoxin use may cause constipation; cases of severe GI reactions including toxic megacolon and adynamic ileus have been reported. Reduced GI motility when combined with opiate agonists may increase the risk of serious GI related adverse events. (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when tramadol is used concomitantly with an anticholinergic drug. The concomitant use of tramadol and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Dolasetron: (Major) Because of the potential risk and severity of serotonin syndrome, use caution when administering dolasetron with other drugs that have serotonergic properties such as tramadol. If serotonin syndrome is suspected, discontinue dolasetron and concurrent serotonergic agents and initiate appropriate medical treatment. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death.
    Doxylamine: (Moderate) Concomitant use of opioid agonists with doxylamine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with doxylamine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Doxylamine; Pyridoxine: (Moderate) Concomitant use of opioid agonists with doxylamine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with doxylamine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Dronabinol: (Moderate) Concomitant use of opioid agonists with dronabinol may cause excessive sedation and somnolence. Limit the use of opioid pain medication with dronabinol to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Dronedarone: (Moderate) Dronedarone is metabolized by CYP3A and is an inhibitor of CYP2D6 and CYP3A. Tramadol is a substrate for CYP2D6 and CYP3A4. The concomitant administration of dronedarone with CYP2D6 and CYP3A substrates may result in increased exposure of the substrate and should, therefore, be undertaken with caution.
    Droperidol: (Major) Concomitant use of opioid agonists with droperidol may cause excessive sedation and somnolence. Limit the use of opioid pain medications with droperidol to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. Educate patients about the risks and symptoms of excessive CNS depression.
    Drospirenone; Ethinyl Estradiol: (Moderate) Acetaminophen may increase plasma ethinyl estradiol levels, possibly by inhibition of conjugation. Patients taking acetaminophen concomitantly may experience an increase in estrogen related side effects.
    Drospirenone; Ethinyl Estradiol; Levomefolate: (Moderate) Acetaminophen may increase plasma ethinyl estradiol levels, possibly by inhibition of conjugation. Patients taking acetaminophen concomitantly may experience an increase in estrogen related side effects.
    Duloxetine: (Major) Because of the potential risk and severity of serotonin syndrome or neuroleptic malignant syndrome-like reactions, caution should be observed when administering serotonin norepinephrine reuptake inhibitors (SNRIs) with other drugs that have serotonergic properties such as tramadol. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. In one case, the addition of tramadol to extended-release venlafaxine (300 mg/day) and mirtazapine (30 mg/day) likely caused serotonin syndrome. A patient developed agitation, confusion, severe shivering, diaphoresis, myoclonus, hyperreflexia, mydriasis, tachycardia, and fever within 7 weeks of taking tramadol 400 mg daily. He had taken 300 mg tramadol without difficulty. Discontinuation of the 3 drugs and rehydration led to symptom resolution over 36 hours. Reinstitution of the antidepressants 3 days after patient presentation was uneventful. Also, duloxetine may inhibit the formation of the active M1 metabolite of tramadol by inhibiting CYP2D6. The inhibition of this metabolite may decrease the analgesic effectiveness of tramadol but increase the level of the parent compound, which has more serotonergic activity than the metabolite. The risk for serious adverse effects such as seizures and serotonin syndrome may be increased. Patients receiving tramadol in combination with an SNRI should be monitored for the emergence of serotonin syndrome, neuroleptic malignant syndrome-like reactions, or other adverse effects.
    Efavirenz: (Moderate) The (+) enantiomer of tramadol preferentially undergoes N-demethylation, which is mediated by CYP3A4 and CYP2B6. Efavirenz is an inducer of CYP3A4 and CYP2B6. Coadministration may affect the metabolism of tramadol leading to altered tramadol exposure. Decreased serum tramadol concentrations and reduced efficacy may occur. In addition, both medications have been associated with the development of seizures; caution is advised. (Minor) Drugs that induce the hepatic isoenzymes CYP2E1 and CYP1A2, such as efavirenz, may potentially increase the risk for acetaminophen-induced hepatotoxicity via generation of a greater percentage of acetaminophen's hepatotoxic metabolite, NAPQI. Also, the analgesic activity of acetaminophen may be reduced.
    Efavirenz; Emtricitabine; Tenofovir: (Moderate) The (+) enantiomer of tramadol preferentially undergoes N-demethylation, which is mediated by CYP3A4 and CYP2B6. Efavirenz is an inducer of CYP3A4 and CYP2B6. Coadministration may affect the metabolism of tramadol leading to altered tramadol exposure. Decreased serum tramadol concentrations and reduced efficacy may occur. In addition, both medications have been associated with the development of seizures; caution is advised. (Minor) Drugs that induce the hepatic isoenzymes CYP2E1 and CYP1A2, such as efavirenz, may potentially increase the risk for acetaminophen-induced hepatotoxicity via generation of a greater percentage of acetaminophen's hepatotoxic metabolite, NAPQI. Also, the analgesic activity of acetaminophen may be reduced.
    Efavirenz; Lamivudine; Tenofovir Disoproxil Fumarate: (Moderate) The (+) enantiomer of tramadol preferentially undergoes N-demethylation, which is mediated by CYP3A4 and CYP2B6. Efavirenz is an inducer of CYP3A4 and CYP2B6. Coadministration may affect the metabolism of tramadol leading to altered tramadol exposure. Decreased serum tramadol concentrations and reduced efficacy may occur. In addition, both medications have been associated with the development of seizures; caution is advised. (Minor) Drugs that induce the hepatic isoenzymes CYP2E1 and CYP1A2, such as efavirenz, may potentially increase the risk for acetaminophen-induced hepatotoxicity via generation of a greater percentage of acetaminophen's hepatotoxic metabolite, NAPQI. Also, the analgesic activity of acetaminophen may be reduced.
    Elagolix: (Moderate) Monitor for reduced efficacy of tramadol and signs of opioid withdrawal if coadministration with elagolix is necessary; consider increasing the dose of tramadol as needed. If elagolix is discontinued, consider a dose reduction of tramadol and frequently monitor for signs or respiratory depression and sedation. Tramadol is a CYP3A4 substrate and elagolix is a weak to moderate CYP3A4 inducer. Concomitant use with CYP3A4 inducers can decrease tramadol levels; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence.
    Elagolix; Estradiol; Norethindrone acetate: (Moderate) Monitor for reduced efficacy of tramadol and signs of opioid withdrawal if coadministration with elagolix is necessary; consider increasing the dose of tramadol as needed. If elagolix is discontinued, consider a dose reduction of tramadol and frequently monitor for signs or respiratory depression and sedation. Tramadol is a CYP3A4 substrate and elagolix is a weak to moderate CYP3A4 inducer. Concomitant use with CYP3A4 inducers can decrease tramadol levels; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence.
    Elbasvir; Grazoprevir: (Moderate) Administering acetaminophen; tramadol with elbasvir; grazoprevir may result in elevated tramadol plasma concentrations. Tramadol is a substrate of CYP3A; grazoprevir is a weak CYP3A inhibitor. If these drugs are used together, closely monitor for signs of adverse events.
    Eletriptan: (Moderate) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering tramadol with serotonin-receptor agonists. Inform patients taking this combination of the possible increased risks and monitor for the emergence of serotonin syndrome particularly during treatment initiation and dose adjustment. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs.
    Elexacaftor; tezacaftor; ivacaftor: (Minor) Use caution when administering ivacaftor and tramadol concurrently. Ivacaftor is an inhibitor of CYP3A and tramadol is partially metabolized by CYP3A. Co-administration can theoretically increase tramadol exposure leading to increased or prolonged therapeutic effects and adverse events; however, the clinical impact of this has not yet been determined.
    Eliglustat: (Moderate) Coadministration of tramadol and eliglustat may result in a reduction in the metabolic conversion and clearance of tramadol, increasing the risk for serious adverse events including seizures and serotonin syndrome. In addition, coadministration of tramadol and eliglustat may result in decreased analgesia. If coadministration is necessary, monitor patients closely for tramadol-related adverse effects and diminished analgesic efficacy. The analgesic activity of tramadol is due to both the parent drug and the pharmacologically active metabolite M1. Because the metabolism of tramadol to M1 is dependent on CYP2D6 and eliglustat is an inhibitor of CYP2D6, therapeutic response may be affected.
    Eltrombopag: (Moderate) Eltrombopag is a UDP-glucuronyltransferase inhibitor. Acetaminophen is a substrate of UDP-glucuronyltransferases. The significance or effect of this interaction is not known; however, elevated concentrations of acetaminophen are possible. Monitor patients for adverse reactions if these drugs are coadministered.
    Elvitegravir; Cobicistat; Emtricitabine; Tenofovir Alafenamide: (Major) As cobicistat is a CYP2D6 and CYP3A4 inhibitor and tramadol is primarily metabolized by CYP2D6 and CYP3A4, concurrent therapy may decrease tramadol metabolism; reduced tramadol dose may be needed during coadministration. This interaction may result in decreased tramadol efficacy and/or increased tramadol-induced risks of serotonin syndrome or seizures. The analgesic activity of tramadol is due to the activity of both the parent drug and the O-desmethyltramadol metabolite (M1), and M1 formation is dependent on CYP2D6. Therefore, use of tramadol with a CYP2D6-inhibitor may alter tramadol efficacy. In addition, inhibition of either or both CYP2D6 and CYP3A4 is expected to result in reduced metabolic clearance of tramadol. This in turn may increase the risk of tramadol-related adverse events including serotonin syndrome and seizures. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death.
    Elvitegravir; Cobicistat; Emtricitabine; Tenofovir Disoproxil Fumarate: (Major) As cobicistat is a CYP2D6 and CYP3A4 inhibitor and tramadol is primarily metabolized by CYP2D6 and CYP3A4, concurrent therapy may decrease tramadol metabolism; reduced tramadol dose may be needed during coadministration. This interaction may result in decreased tramadol efficacy and/or increased tramadol-induced risks of serotonin syndrome or seizures. The analgesic activity of tramadol is due to the activity of both the parent drug and the O-desmethyltramadol metabolite (M1), and M1 formation is dependent on CYP2D6. Therefore, use of tramadol with a CYP2D6-inhibitor may alter tramadol efficacy. In addition, inhibition of either or both CYP2D6 and CYP3A4 is expected to result in reduced metabolic clearance of tramadol. This in turn may increase the risk of tramadol-related adverse events including serotonin syndrome and seizures. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death.
    Enalapril; Hydrochlorothiazide, HCTZ: (Moderate) Monitor for decreased diuretic efficacy and additive orthostatic hypotension when thiazide diuretics are administered with tramadol. Adjustments to diuretic therapy may be needed in some patients. The efficacy of diuretics may be reduced due to opioid-induced release of antidiuretic hormone.
    Enzalutamide: (Moderate) Monitor for reduced efficacy of tramadol and signs of opioid withdrawal if coadministration with enzalutamide is necessary; consider increasing the dose of tramadol as needed. If enzalutamide is discontinued, consider a dose reduction of tramadol and frequently monitor for signs or respiratory depression and sedation. Tramadol is a CYP3A4 substrate and enzalutamide is a strong CYP3A4 inducer. Concomitant use with CYP3A4 inducers can decrease tramadol levels; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence.
    Eprosartan; Hydrochlorothiazide, HCTZ: (Moderate) Monitor for decreased diuretic efficacy and additive orthostatic hypotension when thiazide diuretics are administered with tramadol. Adjustments to diuretic therapy may be needed in some patients. The efficacy of diuretics may be reduced due to opioid-induced release of antidiuretic hormone.
    Erythromycin: (Moderate) Administration of CYP3A4 inhibitors such as erythromycin with tramadol may affect the metabolism of tramadol leading to altered tramadol exposure. Increased serum tramadol concentrations may occur.
    Erythromycin; Sulfisoxazole: (Moderate) Administration of CYP3A4 inhibitors such as erythromycin with tramadol may affect the metabolism of tramadol leading to altered tramadol exposure. Increased serum tramadol concentrations may occur.
    Escitalopram: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering escitalopram with other drugs that have serotonergic properties such as tramadol. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. Several cases of serotonin syndrome have been reported after the administration of tramadol with an SSRI. The combination of SSRIs and tramadol has also been associated with an increased risk of seizures. Post-marketing reports implicate the concurrent use of SSRIs with tramadol in some cases of seizures. Lastly, CYP2D6 inhibitors can prevent the formation of the active M1 metabolite of tramadol by inhibiting CYP2D6. Although escitalopram is a modest inhibitor of CYP2D6, the inhibition of the M1 metabolite may decrease the analgesic effectiveness of tramadol but increase the level of the parent compound, which has more serotonergic activity than the metabolite. Patients receiving tramadol in combination with an SSRI should be monitored for the emergence of serotonin syndrome or other adverse effects.
    Esketamine: (Major) Concomitant use of opioid agonists with esketamine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with esketamine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. Patients who have received a dose of esketamine should be instructed not to drive or engage in other activities requiring complete mental alertness until the next day after a restful sleep. Educate patients about the risks and symptoms of excessive CNS depression.
    Estazolam: (Major) Concomitant use of opiate agonists with benzodiazepines may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opiate pain medications with benzodiazepines to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If an opiate agonist is initiated in a patient taking a benzodiazepine, use a lower initial dose of the opiate and titrate to clinical response. If a benzodiazepine is prescribed for an indication other than epilepsy in a patient taking an opiate agonist, use a lower initial dose of the benzodiazepine and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Eszopiclone: (Moderate) Concomitant use of opioid agonists with eszopiclone may cause excessive sedation, somnolence, and complex sleep-related behaviors (e.g., driving, talking, eating, or performing other activities while not fully awake). Limit the use of opioid pain medications with eszopiclone to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. Instruct patients to contact their provider immediately if sleep-related symptoms or behaviors occur. Educate patients about the risks and symptoms of excessive CNS depression.
    Ethacrynic Acid: (Moderate) Monitor for decreased diuretic efficacy and additive orthostatic hypotension when loop diuretics are administered with tramadol. Adjustments to diuretic therapy may be needed in some patients. The efficacy of diuretics may be reduced due to opioid-induced release of antidiuretic hormone.
    Ethanol: (Major) Advise patients to avoid alcohol consumption while taking opioids. Alcohol consumption may result in additive CNS depression and may increase the risk for opioid overdose. Consider the patient's use of alcohol when prescribing opioid medications. If the patient is unlikely to be compliant with avoiding alcohol, consider prescribing naloxone especially if additional risk factors for opioid overdose are present. (Major) The risk of developing hepatotoxicity from acetaminophen appears to be increased in patients who regularly consume alcohol. Patients who drink more than 3 alcohol-containing drinks a day and take acetaminophen are at increased risk of developing hepatotoxicity. Acute or chronic alcohol use increases acetaminophen-induced hepatotoxicity by inducing cytochrome P450 CYP 2E1 leading to increased formation of the hepatotoxic metabolite of acetaminophen. Also, chronic alcohol use can deplete liver glutathione stores. Administration of acetaminophen should be limited or avoided altogether in patients with alcoholism or patients who consume alcohol regularly.
    Ethinyl Estradiol: (Moderate) Acetaminophen may increase plasma ethinyl estradiol levels, possibly by inhibition of conjugation. Patients taking acetaminophen concomitantly may experience an increase in estrogen related side effects.
    Ethinyl Estradiol; Levonorgestrel; Folic Acid; Levomefolate: (Moderate) Acetaminophen may increase plasma ethinyl estradiol levels, possibly by inhibition of conjugation. Patients taking acetaminophen concomitantly may experience an increase in estrogen related side effects.
    Ethinyl Estradiol; Norelgestromin: (Moderate) Acetaminophen may increase plasma ethinyl estradiol levels, possibly by inhibition of conjugation. Patients taking acetaminophen concomitantly may experience an increase in estrogen related side effects.
    Ethinyl Estradiol; Norethindrone Acetate: (Moderate) Acetaminophen may increase plasma ethinyl estradiol levels, possibly by inhibition of conjugation. Patients taking acetaminophen concomitantly may experience an increase in estrogen related side effects.
    Ethinyl Estradiol; Norgestrel: (Moderate) Acetaminophen may increase plasma ethinyl estradiol levels, possibly by inhibition of conjugation. Patients taking acetaminophen concomitantly may experience an increase in estrogen related side effects.
    Ethiodized Oil: (Major) Tramadol lowers the seizure threshold and should be discontinued at least 48 hours before myelography and should not be resumed for at least 24 hours postprocedure.
    Ethotoin: (Major) Tramadol may decrease the seizure threshold in some patients and thus potentially interfere with the ability of anticonvulsants to control seizures. The use of tramadol in patients on anticonvulsant medications for seizure therapy is not recommended. In addition, the hepatic metabolism of tramadol may be accelerated by the use of ethotoin, phenytoin, or fosphenytoin.
    Ethynodiol Diacetate; Ethinyl Estradiol: (Moderate) Acetaminophen may increase plasma ethinyl estradiol levels, possibly by inhibition of conjugation. Patients taking acetaminophen concomitantly may experience an increase in estrogen related side effects.
    Etonogestrel; Ethinyl Estradiol: (Moderate) Acetaminophen may increase plasma ethinyl estradiol levels, possibly by inhibition of conjugation. Patients taking acetaminophen concomitantly may experience an increase in estrogen related side effects.
    Everolimus: (Moderate) Monitor for an increase in tramadol-related adverse reactions, including serotonin syndrome, seizures, sedation, and respiratory depression, if coadministration with everolimus is necessary; the risk is greatest if everolimus is added to a stable dose of tramadol. Consider decreasing the dose of tramadol if necessary. Everolimus is a weak CYP3A4 inhibitor as well as a CYP2D6 inhibitor. Tramadol is metabolized by both CYP3A4 and CYP2D6.
    Exenatide: (Minor) Although an interaction is possible, these drugs may be used together. To avoid potential pharmacokinetic interactions that might alter effectiveness of acetaminophen, it may be advisable for patients to take acetaminophen at least 1 hour prior to an exenatide injection. When 1,000 mg acetaminophen elixir was given with 10 mcg exenatide (at 0 hours) and at 1, 2 and 4 hours after exenatide injection, acetaminophen AUCs were decreased by 21%, 23%, 24%, and 14%, respectively; Cmax was decreased by 37%, 56%, 54%, and 41%, respectively. Additionally, acetaminophen Tmax was delayed from 0.6 hours in the control period to 0.9, 4.2, 3.3, and 1.6 hours, respectively. Acetaminophen AUC, Cmax, and Tmax were not significantly changed when acetaminophen was given 1 h before exenatide injection. The mechanism of this interaction is not available (although it may be due to delayed gastric emptying from exenatide use) and the clinical impact has not been assessed.
    Ezogabine: (Moderate) Due to the CNS effects of ezogabine, an enhanced CNS depressant effect may occur during concurrent use of other centrally-acting medications such as tramadol. Patients should be monitored for excessive somnolence during concurrent therapy with this agent.
    Fedratinib: (Moderate) Consider a tramadol dosage reduction until stable drug effects are achieved if coadministration with fedratinib is necessary. Closely monitor for seizures, serotonin syndrome, and signs of sedation and respiratory depression. Respiratory depression from increased tramadol exposure may be fatal. Concurrent use of fedratinib, a moderate CYP3A4 inhibitor, may increase tramadol exposure and result in greater CYP2D6 metabolism thereby increasing exposure to the active metabolite M1, which is a more potent mu-opioid agonist.
    Fenfluramine: (Moderate) Concomitant use of opioid agonists with fenfluramine may cause excessive sedation and somnolence. Limit the use of opioid agonists with fenfluramine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. Also monitor patients for the emergence of serotonin syndrome. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs.
    Fentanyl: (Major) Concomitant use of tramadol increases the seizure risk in patients taking opiate agonists. Also, tramadol can cause additive CNS depression and respiratory depression when used with opiate agonists; avoid concurrent use whenever possible. If used together, extreme caution is needed, and a reduced tramadol dose is recommended.
    Fesoterodine: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when fesoterodine, an anticholinergic drug for overactive bladder is used with opiate agonists. The concomitant use of these drugs together may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect. Both agents may also cause drowsiness or blurred vision, and patients should use care in driving or performing other hazardous tasks until the effects of the drugs are known.
    Flavoxate: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when tramadol is used concomitantly with an anticholinergic drug. The concomitant use of tramadol and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Flibanserin: (Moderate) Concomitant use of opioid agonists with flibanserin may cause excessive sedation and somnolence. Limit the use of opioid pain medication with flibanserin to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Fluoxetine: (Moderate) Because of the potential risk and severity of serotonin syndrome or neuroleptic malignant syndrome-like reactions, caution should be observed when administering selective serotonin reuptake inhibitors (SSRIs) with other drugs that have serotonergic properties such as tramadol. Several cases of serotonin syndrome have been reported after the administration of tramadol with a SSRI. Concomitant use of tramadol also increases the seizure risk in patients taking selective serotonin reuptake inhibitors (SSRIs). Post-marketing reports implicate the concurrent use of SSRIs with tramadol in some cases of seizures. Lastly, SSRIs such as fluoxetine may inhibit the formation of the active M1 metabolite of tramadol by inhibiting CYP2D6. The inhibition of this metabolite may decrease the analgesic effectiveness of tramadol but increase the level of the parent compound, which has more serotonergic activity than the metabolite. Patients receiving tramadol in combination with an SSRI should be monitored for the emergence of serotonin syndrome, neuroleptic malignant syndrome-like reactions, or other adverse effects.
    Fluphenazine: (Moderate) Concurrent use of tramadol and fluphenazine should be avoided if possible. Antipsychotics may enhance the seizure risk of tramadol. In addition, in vitro data suggest that fluphenazine is a weak CYP2D6 inhibitor and has the potential to decrease the metabolism of CYP2D6 substrates such as tramadol. Although the full pharmacologic impact of increased tramadol exposure is unknown, close monitoring for serious adverse effects, such as seizures, is advisable. In addition, serotonin syndrome may occur during use of tramadol with medications that impair its metabolism. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Because the analgesic activity of tramadol is due to the activity of both the parent drug and the O-desmethyltramadol metabolite (M1), CYP2D6 inhibition by fluphenazine may alter the analgesic response to tramadol. Additive CNS depression may also be seen with the concomitant use of tramadol and fluphenazine.
    Flurazepam: (Major) Concomitant use of opiate agonists with benzodiazepines may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opiate pain medications with benzodiazepines to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If an opiate agonist is initiated in a patient taking a benzodiazepine, use a lower initial dose of the opiate and titrate to clinical response. If a benzodiazepine is prescribed for an indication other than epilepsy in a patient taking an opiate agonist, use a lower initial dose of the benzodiazepine and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Fluvoxamine: (Major) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering fluvoxamine with other drugs that have serotonergic properties such as tramadol. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Serotonin syndrome, in its most severe form, can resemble neuroleptic malignant syndrome. Several cases of serotonin syndrome have been reported after the administration of tramadol with an SSRI. The combination of SSRIs and tramadol has also been associated with an increased risk of seizures.
    Fosinopril; Hydrochlorothiazide, HCTZ: (Moderate) Monitor for decreased diuretic efficacy and additive orthostatic hypotension when thiazide diuretics are administered with tramadol. Adjustments to diuretic therapy may be needed in some patients. The efficacy of diuretics may be reduced due to opioid-induced release of antidiuretic hormone.
    Fosphenytoin: (Major) Tramadol may decrease the seizure threshold in some patients and thus potentially interfere with the ability of anticonvulsants to control seizures. The use of tramadol in patients on anticonvulsant medications for seizure therapy is not recommended. In addition, the hepatic metabolism of tramadol may be accelerated by the use of ethotoin, phenytoin, or fosphenytoin.
    Fostamatinib: (Moderate) Monitor for tramadol toxicities that may require tramadol dose reduction if given concurrently with fostamatinib. Concomitant use of fostamatinib with a CYP3A4 substrate may increase the concentration of the CYP3A4 substrate. The active metabolite of fostamatinib, R406, is a CYP3A4 inhibitor; tramadol is a substrate for CYP3A4. Coadministration of fostamatinib with a sensitive CYP3A4 substrate increased the substrate AUC by 64% and Cmax by 113%.
    Frovatriptan: (Moderate) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering tramadol with serotonin-receptor agonists. Inform patients taking this combination of the possible increased risks and monitor for the emergence of serotonin syndrome particularly during treatment initiation and dose adjustment. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs.
    Furosemide: (Moderate) Monitor for decreased diuretic efficacy and additive orthostatic hypotension when loop diuretics are administered with tramadol. Adjustments to diuretic therapy may be needed in some patients. The efficacy of diuretics may be reduced due to opioid-induced release of antidiuretic hormone.
    Gabapentin: (Major) Concomitant use of opioid agonists with gabapentin may cause excessive sedation, somnolence, and respiratory depression. Limit the use of opioid pain medications with gabapentin to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, initiate gabapentin at the lowest recommended dose and monitor patients for symptoms of respiratory depression and sedation. Use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. Educate patients about the risks and symptoms of excessive CNS depression and respiratory depression.
    General anesthetics: (Major) Concomitant use of tramadol with a general anesthetic may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medications with a general anesthetic to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Glycopyrrolate: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when tramadol is used concomitantly with an anticholinergic drug. The concomitant use of tramadol and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Glycopyrrolate; Formoterol: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when tramadol is used concomitantly with an anticholinergic drug. The concomitant use of tramadol and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Granisetron: (Major) Because of the potential risk and severity of serotonin syndrome, use caution when administering granisetron with other drugs that have serotonergic properties such as tramadol. If serotonin syndrome is suspected, discontinue granisetron and concurrent serotonergic agents and initiate appropriate medical treatment. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death.
    Guaifenesin; Hydrocodone: (Major) Concomitant use of tramadol increases the seizure risk in patients taking opiate agonists. Also, tramadol can cause additive CNS depression and respiratory depression when used with opiate agonists; avoid concurrent use whenever possible. If used together, extreme caution is needed, and a reduced tramadol dose is recommended.
    Guaifenesin; Hydrocodone; Pseudoephedrine: (Major) Concomitant use of tramadol increases the seizure risk in patients taking opiate agonists. Also, tramadol can cause additive CNS depression and respiratory depression when used with opiate agonists; avoid concurrent use whenever possible. If used together, extreme caution is needed, and a reduced tramadol dose is recommended.
    Guanabenz: (Moderate) Guanabenz is associated with sedative effects. Guanabenz can potentiate the effects of CNS depressants such as opiate agonists, when administered concomitantly.
    Guanfacine: (Moderate) Concomitant use of opioid agonists with guanfacine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with guanfacine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Haloperidol: (Major) Haloperidol can competitively inhibit the metabolism of tramadol by CYP2D6. Concurrent use of haloperidol and tramadol increases plasma levels of tramadol and decreases the concentration of the active tramadol metabolite. This may lead to decreased analgesic effects of tramadol and possibly increased tramadol-induced side effects, including seizures, due to increased tramadol concentrations and the decrease in seizure threshold caused by haloperidol. Additive CNS depression may also be seen with the concomitant use of tramadol and haloperidol.
    Homatropine; Hydrocodone: (Major) Concomitant use of tramadol increases the seizure risk in patients taking opiate agonists. Also, tramadol can cause additive CNS depression and respiratory depression when used with opiate agonists; avoid concurrent use whenever possible. If used together, extreme caution is needed, and a reduced tramadol dose is recommended. (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when tramadol is used concomitantly with an anticholinergic drug. The concomitant use of tramadol and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Hydantoins: (Major) Tramadol may decrease the seizure threshold in some patients and thus potentially interfere with the ability of anticonvulsants to control seizures. The use of tramadol in patients on anticonvulsant medications for seizure therapy is not recommended. In addition, the hepatic metabolism of tramadol may be accelerated by the use of ethotoin, phenytoin, or fosphenytoin. (Minor) Hydantoin anticonvulsants induce hepatic microsomal enzymes and may increase the metabolism of other drugs, leading to reduced efficacy of medications like acetaminophen. In addition, the risk of hepatotoxicity from acetaminophen may be increased with the chronic dosing of acetaminophen along with phenytoin. Adhere to recommended acetaminophen dosage limits. Acetaminophen-related hepatotoxicity has occurred clinically with the concurrent use of acetaminophen 1300 mg to 6200 mg daily and phenytoin. Acetaminophen cessation led to serum transaminase normalization within 2 weeks.
    Hydralazine; Hydrochlorothiazide, HCTZ: (Moderate) Monitor for decreased diuretic efficacy and additive orthostatic hypotension when thiazide diuretics are administered with tramadol. Adjustments to diuretic therapy may be needed in some patients. The efficacy of diuretics may be reduced due to opioid-induced release of antidiuretic hormone.
    Hydrochlorothiazide, HCTZ: (Moderate) Monitor for decreased diuretic efficacy and additive orthostatic hypotension when thiazide diuretics are administered with tramadol. Adjustments to diuretic therapy may be needed in some patients. The efficacy of diuretics may be reduced due to opioid-induced release of antidiuretic hormone.
    Hydrochlorothiazide, HCTZ; Methyldopa: (Moderate) Concomitant use of opioid agonists with methyldopa may cause excessive sedation and somnolence. Limit the use of opioid pain medication with methyldopa to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. (Moderate) Monitor for decreased diuretic efficacy and additive orthostatic hypotension when thiazide diuretics are administered with tramadol. Adjustments to diuretic therapy may be needed in some patients. The efficacy of diuretics may be reduced due to opioid-induced release of antidiuretic hormone.
    Hydrochlorothiazide, HCTZ; Moexipril: (Moderate) Monitor for decreased diuretic efficacy and additive orthostatic hypotension when thiazide diuretics are administered with tramadol. Adjustments to diuretic therapy may be needed in some patients. The efficacy of diuretics may be reduced due to opioid-induced release of antidiuretic hormone.
    Hydrocodone: (Major) Concomitant use of tramadol increases the seizure risk in patients taking opiate agonists. Also, tramadol can cause additive CNS depression and respiratory depression when used with opiate agonists; avoid concurrent use whenever possible. If used together, extreme caution is needed, and a reduced tramadol dose is recommended.
    Hydrocodone; Ibuprofen: (Major) Concomitant use of tramadol increases the seizure risk in patients taking opiate agonists. Also, tramadol can cause additive CNS depression and respiratory depression when used with opiate agonists; avoid concurrent use whenever possible. If used together, extreme caution is needed, and a reduced tramadol dose is recommended.
    Hydrocodone; Phenylephrine: (Major) Concomitant use of tramadol increases the seizure risk in patients taking opiate agonists. Also, tramadol can cause additive CNS depression and respiratory depression when used with opiate agonists; avoid concurrent use whenever possible. If used together, extreme caution is needed, and a reduced tramadol dose is recommended.
    Hydrocodone; Potassium Guaiacolsulfonate: (Major) Concomitant use of tramadol increases the seizure risk in patients taking opiate agonists. Also, tramadol can cause additive CNS depression and respiratory depression when used with opiate agonists; avoid concurrent use whenever possible. If used together, extreme caution is needed, and a reduced tramadol dose is recommended.
    Hydrocodone; Potassium Guaiacolsulfonate; Pseudoephedrine: (Major) Concomitant use of tramadol increases the seizure risk in patients taking opiate agonists. Also, tramadol can cause additive CNS depression and respiratory depression when used with opiate agonists; avoid concurrent use whenever possible. If used together, extreme caution is needed, and a reduced tramadol dose is recommended.
    Hydrocodone; Pseudoephedrine: (Major) Concomitant use of tramadol increases the seizure risk in patients taking opiate agonists. Also, tramadol can cause additive CNS depression and respiratory depression when used with opiate agonists; avoid concurrent use whenever possible. If used together, extreme caution is needed, and a reduced tramadol dose is recommended.
    Hydromorphone: (Major) Tramadol can cause additive CNS depression and respiratory depression when used with opiate agonists such as hydromorphone. Concomitant use of tramadol and opiate agonists may also increase the risk of seizures; avoid concurrent use whenever possible. Prior to concurrent use of hydromorphone in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If hydromorphone is used concurrently with a CNS depressant, a reduced dosage of hydromorphone and/or the CNS depressant is recommended; start with one-third to one-half of the estimated hydromorphone starting dose when using hydromorphone extended-release tablets. Carefully monitor the patient for hypotension, CNS depression, and respiratory depression.
    Hydroxyzine: (Major) Concomitant use of opioid agonists with hydroxyzine may cause excessive sedation and somnolence. Limit the use of opioid pain medications with hydroxyzine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. Educate patients about the risks and symptoms of excessive CNS depression.
    Hyoscyamine: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when tramadol is used concomitantly with an anticholinergic drug. The concomitant use of tramadol and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Hyoscyamine; Methenamine; Methylene Blue; Phenyl Salicylate; Sodium Biphosphate: (Contraindicated) Tramadol use is contraindicated in patients who are receiving or who have received monoamine oxidase inhibitors (MAOIs) within the previous 14 days. Methylene blue is a reversible inhibitor of MAO. Concomitant use of tramadol with other serotonergic drugs such as MAOIs may result in serious adverse effects including serotonin syndrome or seizures. MAOIs may cause additive CNS depression, respiratory depression, drowsiness, dizziness, or hypotension when used with opiate agonists such as tramadol. (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when tramadol is used concomitantly with an anticholinergic drug. The concomitant use of tramadol and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Ibuprofen; Oxycodone: (Major) Concomitant use of tramadol increases the seizure risk in patients taking opiate agonists. Also, tramadol can cause additive CNS depression and respiratory depression when used with opiate agonists; avoid concurrent use whenever possible. If used together, extreme caution is needed, and a reduced tramadol dose is recommended.
    Idelalisib: (Major) Avoid concomitant use of idelalisib, a strong CYP3A inhibitor, with tramadol, a CYP3A substrate, as tramadol toxicities may be significantly increased. The AUC of a sensitive CYP3A substrate was increased 5.4-fold when coadministered with idelalisib.
    Iloperidone: (Moderate) Coadministration should be avoided if possible. Antipsychotics may enhance the seizure risk of tramadol. Additive CNS depression may also be seen with the concomitant use of tramadol and iloperidone.
    Imatinib: (Major) Imatinib, STI-571 may affect the metabolism of acetaminophen. In vitro, imatinib was found to inhibit acetaminophen O-glucuronidation at therapeutic levels. Therefore, systemic exposure to acetaminophen is expected to be increased with coadministration of imatinib. Chronic acetaminophen therapy should be avoided in patients receiving imatinib. (Moderate) Since tramadol is primarily metabolized by cytochrome P450 isoenzyme CYP2D6, agents that inhibit this enzyme, such as imatinib, decrease the metabolism of tramadol. Concomitant use of these agents and tramadol may increase plasma levels of tramadol and decrease concentration of the active metabolite leading to decreased analgesic effects and possibly increased side effects due to higher tramadol concentrations.
    Indacaterol; Glycopyrrolate: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when tramadol is used concomitantly with an anticholinergic drug. The concomitant use of tramadol and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Indapamide: (Moderate) Monitor for decreased diuretic efficacy and additive orthostatic hypotension when indapamide is administered with tramadol. Adjustments to diuretic therapy may be needed in some patients. The efficacy of diuretics may be reduced due to opioid-induced release of antidiuretic hormone.
    Insulin Glargine; Lixisenatide: (Minor) When 1,000 mg acetaminophen was given 1 or 4 hours after 10 mcg lixisenatide, the AUC was not significantly changed, but the acetaminophen Cmax was decreased by 29% and 31%, respectively and median Tmax was delayed by 2 and 1.75 hours, respectively. Acetaminophen AUC, Cmax, and Tmax were not significantly changed when acetaminophen was given 1 h before lixisenatide injection. The mechanism of this interaction is not available (although it may be due to delayed gastric emptying) and the clinical impact has not been assessed. To avoid potential pharmacokinetic interactions that might alter effectiveness of acetaminophen, it may be advisable for patients to take acetaminophen at least one hour prior to lixisenatide subcutaneous injection.
    Iobenguane I 131: (Major) Discontinue tramadol for at least 5 half-lives before the administration of the dosimetry dose or a therapeutic dose of iobenguane I-131. Do not restart tramadol until at least 7 days after each iobenguane I-131 dose. Drugs that reduce catecholamine uptake or deplete catecholamine stores, such as tramadol, may interfere with iobenguane I-131 uptake into cells and interfere with dosimetry calculations resulting in altered iobenguane I-131 efficacy.
    Iodixanol: (Major) Tramadol lowers the seizure threshold and should be discontinued at least 48 hours before myelography and should not be resumed for at least 24 hours postprocedure.
    Iohexol: (Major) Tramadol lowers the seizure threshold and should be discontinued at least 48 hours before myelography and should not be resumed for at least 24 hours postprocedure.
    Iopamidol: (Major) Tramadol lowers the seizure threshold and should be discontinued at least 48 hours before myelography and should not be resumed for at least 24 hours postprocedure.
    Iopromide: (Major) Tramadol lowers the seizure threshold and should be discontinued at least 48 hours before myelography and should not be resumed for at least 24 hours postprocedure.
    Ioversol: (Major) Tramadol lowers the seizure threshold and should be discontinued at least 48 hours before myelography and should not be resumed for at least 24 hours postprocedure.
    Irbesartan; Hydrochlorothiazide, HCTZ: (Moderate) Monitor for decreased diuretic efficacy and additive orthostatic hypotension when thiazide diuretics are administered with tramadol. Adjustments to diuretic therapy may be needed in some patients. The efficacy of diuretics may be reduced due to opioid-induced release of antidiuretic hormone.
    Isavuconazonium: (Moderate) Concomitant use of isavuconazonium with acetaminophen may result in increased serum concentrations of acetaminophen. Acetaminophen is a substrate of the hepatic isoenzyme CYP3A4; isavuconazole, the active moiety of isavuconazonium, is a moderate inhibitor of this enzyme. Caution and close monitoring are advised if these drugs are used together. (Moderate) Concomitant use of isavuconazonium with tramadol may result in increased serum concentrations of tramadol. Tramadol is a substrate of the hepatic isoenzyme CYP3A4; isavuconazole, the active moiety of isavuconazonium, is a moderate inhibitor of this enzyme. Caution and close monitoring are advised if these drugs are used together.
    Isoniazid, INH: (Major) Agents which induce the hepatic isoenzyme CYP2E1, such as isoniazid, may potentially increase the risk for acetaminophen-induced hepatotoxicity via generation of a greater percentage of acetaminophen's hepatotoxic metabolites. The combination of isoniazid and acetaminophen has caused severe hepatotoxicity in at least one patient; studies in rats have demonstrated that pre-treatment with isoniazid potentiates acetaminophen hepatotoxicity. (Major) Use tramadol cautiously, if at all, in patients also receiving a MAOI or a drug with MAO-inhibiting activity such as isoniazid, INH. International recommendations contraindicate the concurrent use of tramadol and MAOIs or the use of tramadol within 14 days of discontinuing MAOI therapy. An increased risk of seizures and serotonin syndrome exists in patients receiving tramadol and MAOIs concurrently. Postmarketing reports of serotonin syndrome with use of tramadol and MAOIs and alpha-2-adrenergic blockers exist. If concomitant treatment of tramadol with a drug affecting the serotonergic neurotransmitter system is clinically warranted, careful observation of the patient is advised, especially during treatment initiation and dose increases.
    Isoniazid, INH; Pyrazinamide, PZA; Rifampin: (Major) Agents which induce the hepatic isoenzyme CYP2E1, such as isoniazid, may potentially increase the risk for acetaminophen-induced hepatotoxicity via generation of a greater percentage of acetaminophen's hepatotoxic metabolites. The combination of isoniazid and acetaminophen has caused severe hepatotoxicity in at least one patient; studies in rats have demonstrated that pre-treatment with isoniazid potentiates acetaminophen hepatotoxicity. (Major) Use tramadol cautiously, if at all, in patients also receiving a MAOI or a drug with MAO-inhibiting activity such as isoniazid, INH. International recommendations contraindicate the concurrent use of tramadol and MAOIs or the use of tramadol within 14 days of discontinuing MAOI therapy. An increased risk of seizures and serotonin syndrome exists in patients receiving tramadol and MAOIs concurrently. Postmarketing reports of serotonin syndrome with use of tramadol and MAOIs and alpha-2-adrenergic blockers exist. If concomitant treatment of tramadol with a drug affecting the serotonergic neurotransmitter system is clinically warranted, careful observation of the patient is advised, especially during treatment initiation and dose increases. (Moderate) Agents which induce the hepatic isoenzymes CYP2E1 and CYP1A2, such as rifampin, may potentially increase the risk for acetaminophen-induced hepatotoxicity via generation of a greater percentage of acetaminophen's hepatotoxic metabolites. (Moderate) Monitor for reduced efficacy of tramadol and signs of opioid withdrawal if coadministration with rifampin is necessary; consider increasing the dose of tramadol as needed. If rifampin is discontinued, consider a dose reduction of tramadol and frequently monitor for seizures, serotonin syndrome, and signs of respiratory depression and sedation. Tramadol is a CYP3A4 substrate and rifampin is a strong CYP3A4 inducer. Concomitant use with CYP3A4 inducers can decrease tramadol levels; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence.
    Isoniazid, INH; Rifampin: (Major) Agents which induce the hepatic isoenzyme CYP2E1, such as isoniazid, may potentially increase the risk for acetaminophen-induced hepatotoxicity via generation of a greater percentage of acetaminophen's hepatotoxic metabolites. The combination of isoniazid and acetaminophen has caused severe hepatotoxicity in at least one patient; studies in rats have demonstrated that pre-treatment with isoniazid potentiates acetaminophen hepatotoxicity. (Major) Use tramadol cautiously, if at all, in patients also receiving a MAOI or a drug with MAO-inhibiting activity such as isoniazid, INH. International recommendations contraindicate the concurrent use of tramadol and MAOIs or the use of tramadol within 14 days of discontinuing MAOI therapy. An increased risk of seizures and serotonin syndrome exists in patients receiving tramadol and MAOIs concurrently. Postmarketing reports of serotonin syndrome with use of tramadol and MAOIs and alpha-2-adrenergic blockers exist. If concomitant treatment of tramadol with a drug affecting the serotonergic neurotransmitter system is clinically warranted, careful observation of the patient is advised, especially during treatment initiation and dose increases. (Moderate) Agents which induce the hepatic isoenzymes CYP2E1 and CYP1A2, such as rifampin, may potentially increase the risk for acetaminophen-induced hepatotoxicity via generation of a greater percentage of acetaminophen's hepatotoxic metabolites. (Moderate) Monitor for reduced efficacy of tramadol and signs of opioid withdrawal if coadministration with rifampin is necessary; consider increasing the dose of tramadol as needed. If rifampin is discontinued, consider a dose reduction of tramadol and frequently monitor for seizures, serotonin syndrome, and signs of respiratory depression and sedation. Tramadol is a CYP3A4 substrate and rifampin is a strong CYP3A4 inducer. Concomitant use with CYP3A4 inducers can decrease tramadol levels; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence.
    Isosulfan Blue: (Major) Tramadol lowers the seizure threshold and should be discontinued at least 48 hours before myelography and should not be resumed for at least 24 hours postprocedure.
    Istradefylline: (Moderate) Consider a tramadol dosage reduction until stable drug effects are achieved if coadministration with istradefylline 40 mg daily is necessary. Closely monitor for seizures, serotonin syndrome, and signs of sedation and respiratory depression. Respiratory depression from increased tramadol exposure may be fatal. Concurrent use of istradefylline 40 mg daily, a weak CYP3A4 inhibitor, may increase tramadol exposure and result in greater CYP2D6 metabolism thereby increasing exposure to the active metabolite M1, which is a more potent mu-opioid agonist. There was no effect on drug exposure when istradefylline 20 mg daily was coadministered with a sensitive CYP3A4 substrate.
    Ivacaftor: (Minor) Use caution when administering ivacaftor and tramadol concurrently. Ivacaftor is an inhibitor of CYP3A and tramadol is partially metabolized by CYP3A. Co-administration can theoretically increase tramadol exposure leading to increased or prolonged therapeutic effects and adverse events; however, the clinical impact of this has not yet been determined.
    Ketoconazole: (Moderate) Administration of CYP3A4 inhibitors such as ketoconazole with tramadol may affect the metabolism of tramadol leading to altered tramadol exposure. Increased serum tramadol concentrations may occur.
    Lamivudine, 3TC; Zidovudine, ZDV: (Minor) Both acetaminophen and zidovudine, ZDV undergo glucuronidation. Competition for the metabolic pathway is thought to have caused a case of acetaminophen-related hepatotoxicity. This interaction may be more clinically significant in patients with depleted glutathione stores, such as patients with acquired immunodeficiency syndrome, poor nutrition, or alcoholism.
    Lamotrigine: (Major) Acetaminophen can be hepatotoxic, and lamotrigine appears to be a potential cause of progressive and fatal hepatotoxicity despite drug discontinuation. A 35 year-old developed fulminant liver failure possibly caused by lamotrigine. She was taking several other drugs including acetaminophen. In a randomized, single-dose study, the serum half-life of lamotrigine after a 300 mg dose decreased by 15% and the area under the plasma concentration-time curve decreased by 20% when given with acetaminophen 900 mg 3 times a day as compared with administration of lamotrigine with placebo. As the lamotrigine maximum serum concentration (Cmax) and time to Cmax was similar between the groups, and the lamotrigine renal clearance increased by 7%, acetaminophen appears to enhance removal of lamotrigine from the circulation.
    Lanthanum Carbonate: (Minor) The manufacturer recommends that oral compounds known to interact with antacids, such as acetaminophen, should not be taken within 2 hours of dosing with lanthanum carbonate.
    Lapatinib: (Moderate) Consider a tramadol dosage reduction until stable drug effects are achieved if coadministration with lapatinib is necessary. Closely monitor for seizures, serotonin syndrome, and signs of sedation and respiratory depression. Respiratory depression from increased tramadol exposure may be fatal. Concurrent use of lapatinib, a weak CYP3A4 inhibitor, may increase tramadol exposure and result in greater CYP2D6 metabolism thereby increasing exposure to the active metabolite M1, which is a more potent mu-opioid agonist.
    Larotrectinib: (Moderate) Consider a tramadol dosage reduction until stable drug effects are achieved if coadministration with larotrectinib is necessary. Closely monitor for seizures, serotonin syndrome, and signs of sedation and respiratory depression. Respiratory depression from increased tramadol exposure may be fatal. Concurrent use of larotrectinib, a weak CYP3A4 inhibitor, may increase tramadol exposure and result in greater CYP2D6 metabolism thereby increasing exposure to the active metabolite M1, which is a more potent mu-opioid agonist.
    Lasmiditan: (Moderate) Concomitant use of tramadol with lasmiditan may cause excessive sedation, somnolence, and serotonin syndrome. Limit the use of tramadol with lasmiditan to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. Educate patients about the risks and symptoms of excessive CNS depression and serotonin syndrome.
    Lefamulin: (Moderate) Consider a tramadol dosage reduction until stable drug effects are achieved if coadministration with oral lefamulin is necessary. Closely monitor for seizures, serotonin syndrome, and signs of sedation and respiratory depression. Respiratory depression from increased tramadol exposure may be fatal. Concurrent use of oral lefamulin, a moderate CYP3A4 inhibitor, may increase tramadol exposure and result in greater CYP2D6 metabolism thereby increasing exposure to the active metabolite M1, which is a more potent mu-opioid agonist. An interaction is not expected with intravenous lefamulin.
    Lemborexant: (Moderate) Concomitant use of tramadol with lemborexant may cause excessive sedation and somnolence. Limit the use of tramadol with lemborexant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. Educate patients about the risks and symptoms of excessive CNS depression.
    Letermovir: (Moderate) Consider a tramadol dosage reduction until stable drug effects are achieved if coadministration with letermovir is necessary. Closely monitor for seizures, serotonin syndrome, and signs of sedation and respiratory depression. Respiratory depression from increased tramadol exposure may be fatal. Concurrent use of letermovir, a CYP3A4 inhibitor, may increase tramadol exposure and result in greater CYP2D6 metabolism thereby increasing exposure to the active metabolite M1, which is a more potent mu-opioid agonist.
    Levamlodipine: (Moderate) Consider a tramadol dosage reduction until stable drug effects are achieved if coadministration with amlodipine is necessary. Closely monitor for seizures, serotonin syndrome, and signs of sedation and respiratory depression. Respiratory depression from increased tramadol exposure may be fatal. Concurrent use of amlodipine, a weak CYP3A4 inhibitor, may increase tramadol exposure and result in greater CYP2D6 metabolism thereby increasing exposure to the active metabolite M1, which is a more potent mu-opioid agonist.
    Levocetirizine: (Moderate) Concomitant use of opioid agonists with cetirizine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with cetirizine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Levomilnacipran: (Moderate) If concomitant use of tramadol and levomilnacipran is warranted, monitor patients for seizures and the emergence of serotonin syndrome. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. Concomitant use of tramadol and levomilnacipran may increase seizure risk. The concomitant use of opioids with other drugs that affect the serotonergic neurotransmitter system has resulted in serotonin syndrome.
    Levonorgestrel; Ethinyl Estradiol: (Moderate) Acetaminophen may increase plasma ethinyl estradiol levels, possibly by inhibition of conjugation. Patients taking acetaminophen concomitantly may experience an increase in estrogen related side effects.
    Levonorgestrel; Ethinyl Estradiol; Ferrous Bisglycinate: (Moderate) Acetaminophen may increase plasma ethinyl estradiol levels, possibly by inhibition of conjugation. Patients taking acetaminophen concomitantly may experience an increase in estrogen related side effects.
    Levorphanol: (Major) Concomitant use of tramadol increases the seizure risk in patients taking opiate agonists. Also, tramadol can cause additive CNS depression and respiratory depression when used with opiate agonists; avoid concurrent use whenever possible. If used together, extreme caution is needed, and a reduced tramadol dose is recommended.
    Lidocaine: (Moderate) Coadministration of lidocaine with oxidizing agents, such as acetaminophen, may increase the risk of developing methemoglobinemia. Monitor patients closely for signs and symptoms of methemoglobinemia if coadministration is necessary. If methemoglobinemia occurs or is suspected, discontinue lidocaine and any other oxidizing agents. Depending on the severity of symptoms, patients may respond to supportive care; more severe symptoms may require treatment with methylene blue, exchange transfusion, or hyperbaric oxygen.
    Lidocaine; Prilocaine: (Moderate) Coadministration of lidocaine with oxidizing agents, such as acetaminophen, may increase the risk of developing methemoglobinemia. Monitor patients closely for signs and symptoms of methemoglobinemia if coadministration is necessary. If methemoglobinemia occurs or is suspected, discontinue lidocaine and any other oxidizing agents. Depending on the severity of symptoms, patients may respond to supportive care; more severe symptoms may require treatment with methylene blue, exchange transfusion, or hyperbaric oxygen. (Moderate) Coadministration of prilocaine with oxidizing agents, such as acetaminophen, may increase the risk of developing methemoglobinemia. Monitor patients closely for signs and symptoms of methemoglobinemia if coadministration is necessary. If methemoglobinemia occurs or is suspected, discontinue prilocaine and any other oxidizing agents. Depending on the severity of symptoms, patients may respond to supportive care; more severe symptoms may require treatment with methylene blue, exchange transfusion, or hyperbaric oxygen.
    Linezolid: (Contraindicated) Tramadol use is contraindicated in patients who are receiving or who have received monoamine oxidase inhibitors (MAOIs) within the previous 14 days. Linezolid is a reversible, non-selective inhibitor of MAO. Concomitant use of tramadol with other serotonergic drugs such as MAOIs may result in serious adverse effects including serotonin syndrome or seizures. MAOIs may cause additive CNS depression, respiratory depression, drowsiness, dizziness, or hypotension when used with opiate agonists such as tramadol.
    Lisdexamfetamine: (Moderate) If concomitant use of tramadol and lisdexamfetamine is warranted, monitor patients for the emergence of serotonin syndrome. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. The concomitant use of opioids with other drugs that affect the serotonergic neurotransmitter system has resulted in serotonin syndrome.
    Lisinopril; Hydrochlorothiazide, HCTZ: (Moderate) Monitor for decreased diuretic efficacy and additive orthostatic hypotension when thiazide diuretics are administered with tramadol. Adjustments to diuretic therapy may be needed in some patients. The efficacy of diuretics may be reduced due to opioid-induced release of antidiuretic hormone.
    Lithium: (Moderate) If concomitant use of tramadol and lithium is warranted, monitor patients for the emergence of serotonin syndrome. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. The concomitant use of opioids with other drugs that affect the serotonergic neurotransmitter system has resulted in serotonin syndrome.
    Lixisenatide: (Minor) When 1,000 mg acetaminophen was given 1 or 4 hours after 10 mcg lixisenatide, the AUC was not significantly changed, but the acetaminophen Cmax was decreased by 29% and 31%, respectively and median Tmax was delayed by 2 and 1.75 hours, respectively. Acetaminophen AUC, Cmax, and Tmax were not significantly changed when acetaminophen was given 1 h before lixisenatide injection. The mechanism of this interaction is not available (although it may be due to delayed gastric emptying) and the clinical impact has not been assessed. To avoid potential pharmacokinetic interactions that might alter effectiveness of acetaminophen, it may be advisable for patients to take acetaminophen at least one hour prior to lixisenatide subcutaneous injection.
    Lofexidine: (Moderate) Monitor for excessive hypotension and sedation during coadministration of lofexidine and tramadol. Lofexidine can potentiate the effects of CNS depressants.
    Lomitapide: (Moderate) Caution should be exercised when lomitapide is used with other medications known to have potential for hepatotoxicity, such as acetaminophen (> 4 g/day PO for >= 3 days/week). The effect of concomitant administration of lomitapide with other hepatotoxic medications is unknown. More frequent monitoring of liver-related tests may be warranted.
    Lonafarnib: (Moderate) Consider a tramadol dosage reduction until stable drug effects are achieved if coadministration with lonafarnib is necessary. Closely monitor for seizures, serotonin syndrome, and signs of sedation and respiratory depression. Respiratory depression from increased tramadol exposure may be fatal. Concurrent use of lonafarnib, a strong CYP3A4 inhibitor, may increase tramadol exposure and result in greater CYP2D6 metabolism thereby increasing exposure to the active metabolite M1, which is a more potent mu-opioid agonist.
    Loop diuretics: (Moderate) Monitor for decreased diuretic efficacy and additive orthostatic hypotension when loop diuretics are administered with tramadol. Adjustments to diuretic therapy may be needed in some patients. The efficacy of diuretics may be reduced due to opioid-induced release of antidiuretic hormone.
    Lopinavir; Ritonavir: (Major) Tramadol is primarily metabolized by CYP2D6 and CYP3A4; drugs that inhibit these enzymes, such as ritonavir, may decrease the metabolism of tramadol. This may result in a decreased concentration of the active metabolite (O-desmethyltramadol) leading to decreased analgesic effects and possibly increased side effects (seizures and serotonin syndrome) due to higher tramadol concentrations. (Moderate) Concurrent administration of acetaminophen with ritonavir may result in elevated acetaminophen plasma concentrations and subsequent adverse events. Acetaminophen is metabolized by the hepatic isoenzyme CYP3A4; ritonavir is an inhibitor of this enzyme. Caution and close monitoring are advised if these drugs are administered together.
    Lorazepam: (Major) Concomitant use of opiate agonists with benzodiazepines may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opiate pain medications with benzodiazepines to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If an opiate agonist is initiated in a patient taking a benzodiazepine, use a lower initial dose of the opiate and titrate to clinical response. If a benzodiazepine is prescribed for an indication other than epilepsy in a patient taking an opiate agonist, use a lower initial dose of the benzodiazepine and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Lorcaserin: (Moderate) Monitor patients closely for adverse reactions including opioid withdrawal, seizures, and serotonin syndrome if coadministration with lorcaserin is necessary. If lorcaserin is discontinued, consider a tramadol dosage reduction until stable drug effects are achieved. Monitor patients closely for adverse events including respiratory depression and sedation. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. Concurrent use of lorcaserin, a CYP2D6 inhibitor, may increase tramadol exposure and decrease exposure to the active metabolite M1. Since M1 is a more potent mu-opioid agonist, decreased M1 exposure could result in decreased therapeutic effects. Increased tramadol exposure can result in increased or prolonged therapeutic effects and increased risk for serious adverse events.
    Lorlatinib: (Moderate) Monitor for reduced efficacy of tramadol and signs of opioid withdrawal if coadministration with lorlatinib is necessary; consider increasing the dose of tramadol as needed. If lorlatinib is discontinued, consider a dose reduction of tramadol and frequently monitor for signs or respiratory depression and sedation. Tramadol is a CYP3A4 substrate and lorlatinib is a moderate CYP3A4 inducer. Concomitant use with CYP3A4 inducers can decrease tramadol levels; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence.
    Losartan; Hydrochlorothiazide, HCTZ: (Moderate) Monitor for decreased diuretic efficacy and additive orthostatic hypotension when thiazide diuretics are administered with tramadol. Adjustments to diuretic therapy may be needed in some patients. The efficacy of diuretics may be reduced due to opioid-induced release of antidiuretic hormone.
    Loxapine: (Moderate) Concomitant use of opioid agonists with loxapine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with loxapine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. Also, concomitant use of tramadol increases the seizure risk in patients taking loxapine.
    Lumacaftor; Ivacaftor: (Minor) Use caution when administering ivacaftor and tramadol concurrently. Ivacaftor is an inhibitor of CYP3A and tramadol is partially metabolized by CYP3A. Co-administration can theoretically increase tramadol exposure leading to increased or prolonged therapeutic effects and adverse events; however, the clinical impact of this has not yet been determined.
    Lumacaftor; Ivacaftor: (Moderate) Lumacaftor; ivacaftor may reduce the analgesic effect of tramadol by decreasing its systemic exposure. If used together, monitor patients closely for loss of tramadol efficacy; a tramadol dosage adjustment may be required to obtain the desired therapeutic effect. Do not exceed the maximum recommended dose. Tramadol preferentially undergoes N-demethylation, which is mediated by CYP3A4 and CYP2B6. Lumacaftor is a strong CYP3A inducer; in vitro data also suggest that lumacaftor may induce CYP2B6.
    Lumateperone: (Moderate) Concomitant use of opioid agonists like tramadol with lumateperone may cause excessive sedation and somnolence. Limit the use of opioid pain medication with lumateperone to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. Also, concomitant use of tramadol increases the seizure risk in patients taking lumateperone.
    Lurasidone: (Moderate) Concomitant use of opioid agonists like tramadol with lurasidone may cause excessive sedation and somnolence. Limit the use of opioid pain medication with lurasidone to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. Also, concomitant use of tramadol increases the seizure risk in patients taking lurasidone.
    Magnesium Salicylate: (Moderate) Prolonged concurrent use of acetaminophen and salicylates is not recommended. Although salicylates are rarely associated with nephrotoxicity, high-dose, chronic administration of salicylates combined other analgesics, including acetaminophen, significantly increases the risk of analgesic nephropathy, renal papillary necrosis, and end-stage renal disease. Additive hepatic toxicity may occur, especially in combined overdose situations. Do not exceed the recommended individual maximum doses when these agents are given concurrently for short-term therapy.
    Magnesium Salts: (Minor) Because of the CNS-depressant effects of magnesium sulfate, additive central-depressant effects can occur following concurrent administration with CNS depressants such as opiate agonists. Caution should be exercised when using these agents concurrently.
    Maprotiline: (Major) Concomitant use of opioid agonists with maprotiline may cause excessive sedation and somnolence. Use of tramadol may also increase the risk of seizures in patients receiving other drugs associated with seizures such as maprotiline. Limit the use of opioid pain medications with maprotiline to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. Educate patients about the risks and symptoms of excessive CNS depression and seizures.
    Melatonin: (Moderate) Concomitant use of opioid agonists with melatonin may cause excessive sedation and somnolence. Limit the use of opioid pain medications with melatonin to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. Educate patients about the risks and symptoms of excessive CNS depression.
    Mepenzolate: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when tramadol is used concomitantly with an anticholinergic drug. The concomitant use of tramadol and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Meperidine: (Major) Concomitant use of tramadol increases the seizure risk in patients taking opiate agonists. Also, tramadol can cause additive CNS depression and respiratory depression when used with opiate agonists; avoid concurrent use whenever possible. If used together, extreme caution is needed, and a reduced tramadol dose is recommended.
    Meperidine; Promethazine: (Major) Concomitant use of tramadol increases the seizure risk in patients taking opiate agonists. Also, tramadol can cause additive CNS depression and respiratory depression when used with opiate agonists; avoid concurrent use whenever possible. If used together, extreme caution is needed, and a reduced tramadol dose is recommended. (Moderate) Caution is advisable during concurrent use of tramadol and promethazine. Seizures have been reported in patients receiving monotherapy with both tramadol and promethazine at recommended doses. Concomitant use of tramadol and promethazine may increase the risk of seizures. In addition, due to the primary CNS effects of promethazine, caution is advisable during use of other centrally acting medications such as tramadol. Impairment of metabolism of tramadol by CYP2D6 inhibitors, such as promethazine, may increase the risk of serotonin syndrome. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. The analgesic activity of tramadol is due to the activity of both the parent drug and the O-desmethyltramadol metabolite (M1), and M1 formation is dependent on CYP2D6. Therefore, use of tramadol with a CYP2D6 inhibitor may decrease tramadol analgesic efficacy.
    Mephobarbital: (Major) Concomitant use of tramadol with barbiturates may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medications with barbiturates to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation. Additionally, concomitant use of tramadol with a barbiturate can decrease tramadol concentrations; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence. Monitor for reduced efficacy of tramadol and signs of opioid withdrawal. Discontinuation of a barbiturate may increase the risk of seizures, serotonin syndrome, and the risk of opioid-related adverse reactions, such as fatal respiratory depression. Barbiturates induce CYP3A4; tramadol is a CYP3A4 substrate. (Minor) Chronic therapy with barbiturates can increase the metabolism and decrease the effectiveness of acetaminophen. During acute overdoses, barbiturates can enhance the formation of toxic acetaminophen metabolites.
    Mepivacaine: (Moderate) Coadministration of mepivacaine with oxidizing agents, such as acetaminophen, may increase the risk of developing methemoglobinemia. Monitor patients closely for signs and symptoms of methemoglobinemia if coadministration is necessary. If methemoglobinemia occurs or is suspected, discontinue mepivacaine and any other oxidizing agents. Depending on the severity of symptoms, patients may respond to supportive care; more severe symptoms may require treatment with methylene blue, exchange transfusion, or hyperbaric oxygen.
    Mepivacaine; Levonordefrin: (Moderate) Coadministration of mepivacaine with oxidizing agents, such as acetaminophen, may increase the risk of developing methemoglobinemia. Monitor patients closely for signs and symptoms of methemoglobinemia if coadministration is necessary. If methemoglobinemia occurs or is suspected, discontinue mepivacaine and any other oxidizing agents. Depending on the severity of symptoms, patients may respond to supportive care; more severe symptoms may require treatment with methylene blue, exchange transfusion, or hyperbaric oxygen.
    Meprobamate: (Moderate) Tramadol use increases the risk of CNS depression and respiratory depression when used with other agents that are CNS depressants such as meprobamate. Extreme caution is needed in using tramadol at the same time as other CNS depressants. A reduced dose of tramadol is recommended when used with another CNS depressant.
    Mesoridazine: (Moderate) Due to the primary CNS effects of phenothiazines, caution should be used when given in combination with other centrally acting medications, such as tramadol. Both of these medications can lower the seizure threshold when used alone, therefore there is an even greater risk when they are used concomitantly.
    Metaxalone: (Major) Concomitant use of opioid agonists with metaxalone may cause excessive sedation and somnolence. Limit the use of opioid pain medications with metaxalone to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. If concomitant use of tramadol and metaxalone is warranted, monitor patients for the emergence of serotonin syndrome. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. The concomitant use of opioids with other drugs that affect the serotonergic neurotransmitter system has resulted in serotonin syndrome.
    Methadone: (Major) Concomitant use of tramadol increases the seizure risk in patients taking opiate agonists. Also, tramadol can cause additive CNS depression and respiratory depression when used with opiate agonists; avoid concurrent use whenever possible. If used together, extreme caution is needed, and a reduced tramadol dose is recommended.
    Methamphetamine: (Moderate) If concomitant use of tramadol and methamphetamine is warranted, monitor patients for the emergence of serotonin syndrome. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. The concomitant use of opioids with other drugs that affect the serotonergic neurotransmitter system has resulted in serotonin syndrome.
    Methenamine; Sodium Acid Phosphate; Methylene Blue; Hyoscyamine: (Contraindicated) Tramadol use is contraindicated in patients who are receiving or who have received monoamine oxidase inhibitors (MAOIs) within the previous 14 days. Methylene blue is a reversible inhibitor of MAO. Concomitant use of tramadol with other serotonergic drugs such as MAOIs may result in serious adverse effects including serotonin syndrome or seizures. MAOIs may cause additive CNS depression, respiratory depression, drowsiness, dizziness, or hypotension when used with opiate agonists such as tramadol. (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when tramadol is used concomitantly with an anticholinergic drug. The concomitant use of tramadol and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Methocarbamol: (Major) Concomitant use of tramadol with a skeletal muscle relaxant may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medications with a skeletal muscle relaxant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Methohexital: (Major) Concomitant use of tramadol with barbiturates may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medications with barbiturates to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation. Additionally, concomitant use of tramadol with a barbiturate can decrease tramadol concentrations; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence. Monitor for reduced efficacy of tramadol and signs of opioid withdrawal. Discontinuation of a barbiturate may increase the risk of seizures, serotonin syndrome, and the risk of opioid-related adverse reactions, such as fatal respiratory depression. Barbiturates induce CYP3A4; tramadol is a CYP3A4 substrate. (Minor) Chronic therapy with barbiturates can increase the metabolism and decrease the effectiveness of acetaminophen. During acute overdoses, barbiturates can enhance the formation of toxic acetaminophen metabolites.
    Methscopolamine: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when tramadol is used concomitantly with an anticholinergic drug. The concomitant use of tramadol and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Methyclothiazide: (Moderate) Monitor for decreased diuretic efficacy and additive orthostatic hypotension when thiazide diuretics are administered with tramadol. Adjustments to diuretic therapy may be needed in some patients. The efficacy of diuretics may be reduced due to opioid-induced release of antidiuretic hormone.
    Methyldopa: (Moderate) Concomitant use of opioid agonists with methyldopa may cause excessive sedation and somnolence. Limit the use of opioid pain medication with methyldopa to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Methylene Blue: (Contraindicated) Tramadol use is contraindicated in patients who are receiving or who have received monoamine oxidase inhibitors (MAOIs) within the previous 14 days. Methylene blue is a reversible inhibitor of MAO. Concomitant use of tramadol with other serotonergic drugs such as MAOIs may result in serious adverse effects including serotonin syndrome or seizures. MAOIs may cause additive CNS depression, respiratory depression, drowsiness, dizziness, or hypotension when used with opiate agonists such as tramadol.
    Methylphenidate Derivatives: (Moderate) If concomitant use of tramadol and methylphenidate derivatives is warranted, monitor patients for the emergence of serotonin syndrome. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. The concomitant use of opioids with other drugs that affect the serotonergic neurotransmitter system has resulted in serotonin syndrome.
    Metoclopramide: (Moderate) The effects of metoclopramide on gastrointestinal motility are antagonized by narcotic analgesics. Concomitant use of opioid agonists with metoclopramide may also cause excessive sedation and somnolence. Limit the use of opioid pain medications with metoclopramide to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. Educate patients about the risks and symptoms of excessive CNS depression.
    Metolazone: (Moderate) Monitor for decreased diuretic efficacy and additive orthostatic hypotension when thiazide diuretics are administered with tramadol. Adjustments to diuretic therapy may be needed in some patients. The efficacy of diuretics may be reduced due to opioid-induced release of antidiuretic hormone.
    Metoprolol; Hydrochlorothiazide, HCTZ: (Moderate) Monitor for decreased diuretic efficacy and additive orthostatic hypotension when thiazide diuretics are administered with tramadol. Adjustments to diuretic therapy may be needed in some patients. The efficacy of diuretics may be reduced due to opioid-induced release of antidiuretic hormone.
    Metyrapone: (Major) Coadministration of metyrapone and acetaminophen may result in acetaminophen toxicity. Acetaminophen glucuronidation is inhibited by metyrapone. It may be advisable for patients to avoid acetaminophen while taking metyrapone.
    Metyrosine: (Moderate) The concomitant administration of metyrosine with opiate agonists can result in additive sedative effects.
    Midazolam: (Major) Concomitant use of opiate agonists with benzodiazepines may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opiate pain medications with benzodiazepines to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If an opiate agonist is initiated in a patient taking a benzodiazepine, use a lower initial dose of the opiate and titrate to clinical response. If a benzodiazepine is prescribed for an indication other than epilepsy in a patient taking an opiate agonist, use a lower initial dose of the benzodiazepine and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Milnacipran: (Moderate) If concomitant use of tramadol and milnacipran is warranted, monitor patients for the emergence of serotonin syndrome. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. The concomitant use of opioids with other drugs that affect the serotonergic neurotransmitter system has resulted in serotonin syndrome.
    Minocycline: (Minor) Injectable minocycline contains magnesium sulfate heptahydrate. Because of the CNS-depressant effects of magnesium sulfate, additive central-depressant effects can occur following concurrent administration with CNS depressants such as opiate agonists. Caution should be exercised when using these agents concurrently.
    Mipomersen: (Moderate) Caution should be exercised when mipomersen is used with other medications known to have potential for hepatotoxicity, such as acetaminophen (> 4 g/day for >= 3 days/week). The effect of concomitant administration of mipomersen with other hepatotoxic medications is unknown. More frequent monitoring of liver-related tests may be warranted.
    Mirabegron: (Moderate) Mirabegron is a moderate CYP2D6 inhibitor. Exposure of drugs metabolized by CYP2D6 such as tramadol may be increased when co-administered with mirabegron. Tramadol is primarily metabolized by CYP2D6. Therefore, appropriate monitoring and dose adjustment may be necessary.
    Mirtazapine: (Major) Concomitant use of opioid agonists with mirtazapine may cause excessive sedation and somnolence. Limit the use of opioid pain medications with mirtazapine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Also monitor patients for the emergence of serotonin syndrome. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. The concomitant use of opioids with other drugs that affect the serotonergic neurotransmitter system has resulted in serotonin syndrome.
    Mitotane: (Major) Use caution if mitotane and tramadol are used concomitantly, and monitor for decreased efficacy of tramadol and a possible change in dosage requirements. Mitotane is a strong CYP3A4 inducer. The metabolism of tramadol is stereoselective; the (+) enantiomer preferentially undergoes N-demethylation, mediated by CYP3A4 and CYP2B6, and the (-) enantiomer undergoes O-demethylation via CYP2D6. O-demethylation leads to the production of the active metabolite M1, which is critical to tramadol activity. Because of the role of CYP3A4 in tramadol metabolism, coadministration with mitotane may affect patient response to tramadol. (Minor) Use caution if mitotane and acetaminophen are used concomitantly, and monitor for decreased efficacy of acetaminophen. Mitotane is a strong CYP3A4 inducer and acetaminophen is a minor (10% to 15%) CYP3A4 substrate; coadministration may result in decreased plasma concentrations of acetaminophen.
    Mobocertinib: (Moderate) Monitor for reduced efficacy of tramadol and signs of opioid withdrawal if coadministration with mobocertinib is necessary; consider increasing the dose of tramadol as needed. If mobocertinib is discontinued, consider a dose reduction of tramadol and frequently monitor for seizures, serotonin syndrome, and signs of respiratory depression and sedation. Tramadol is a CYP3A substrate and mobocertinib is a weak CYP3A inducer. Concomitant use with CYP3A inducers can decrease tramadol levels; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence.
    Molindone: (Major) Concomitant use of opioid agonists like tramadol with molindone may cause excessive sedation and somnolence. Limit the use of opioid pain medications with molindone to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Also, concomitant use of tramadol increases the seizure risk in patients taking molindone.
    Monoamine oxidase inhibitors: (Contraindicated) Tramadol use is contraindicated in patients who are receiving or who have received monoamine oxidase inhibitors (MAOIs) within the previous 14 days due to a risk for serotonin syndrome or opioid toxicity, including respiratory depression.
    Morphine: (Major) Concomitant use of tramadol increases the seizure risk in patients taking opiate agonists. Also, because of the potential risk and severity of serotonin syndrome, caution and careful monitoring are recommended when coadministering drugs that have serotonergic properties such as morphine and tramadol. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Morphine and tramadol should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated. Lastly, tramadol can cause additive CNS depression and respiratory depression when used with opiate agonists; avoid concurrent use whenever possible. If used together, extreme caution is needed, and a reduced tramadol dose is recommended.
    Morphine; Naltrexone: (Major) Concomitant use of tramadol increases the seizure risk in patients taking opiate agonists. Also, because of the potential risk and severity of serotonin syndrome, caution and careful monitoring are recommended when coadministering drugs that have serotonergic properties such as morphine and tramadol. Serotonin syndrome is characterized by the rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. Morphine and tramadol should be discontinued if serotonin syndrome occurs and supportive symptomatic treatment should be initiated. Lastly, tramadol can cause additive CNS depression and respiratory depression when used with opiate agonists; avoid concurrent use whenever possible. If used together, extreme caution is needed, and a reduced tramadol dose is recommended.
    Nabilone: (Major) Avoid coadministration of opioid agonists with nabilone due to the risk of additive CNS depression.
    Nalbuphine: (Major) Avoid the concomitant use of nalbuphine and opiate agonists, such as tramadol. Nalbuphine is a mixed opiate agonist/antagonist that may block the effects of opiate agonists and reduce analgesic effects. Nalbuphine may cause withdrawal symptoms in patients receiving chronic opiate agonists. Concurrent use of nalbuphine with other opiate agonists can cause additive CNS, respiratory, and hypotensive effects. The additive or antagonistic effects are dependent upon the dose of the opiate agonist used; antagonistic effects are more common at low to moderate doses of the opiate agonist. There is also a potential increased risk of seizures if tramadol is given with other opiates.
    Naratriptan: (Moderate) Because of the potential risk and severity of serotonin syndrome, caution should be observed when administering tramadol with serotonin-receptor agonists. Inform patients taking this combination of the possible increased risks and monitor for the emergence of serotonin syndrome particularly during treatment initiation and dose adjustment. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs.
    Nefazodone: (Moderate) Consider a tramadol dosage reduction until stable drug effects are achieved if coadministration with nefazodone is necessary. Closely monitor for seizures, serotonin syndrome, and signs of sedation and respiratory depression. Respiratory depression from increased tramadol exposure may be fatal. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. Concurrent use of nefazodone, a strong CYP3A4 inhibitor, may increase tramadol exposure and result in greater CYP2D6 metabolism thereby increasing exposure to the active metabolite M1, which is a more potent mu-opioid agonist. The concomitant use of opioids with other drugs that affect the serotonergic neurotransmitter system has resulted in serotonin syndrome.
    Nesiritide, BNP: (Major) The potential for hypotension may be increased when coadministering nesiritide with opiate agonists.
    Netupitant, Fosnetupitant; Palonosetron: (Moderate) If concomitant use of tramadol and palonosetron is warranted, monitor patients for the emergence of serotonin syndrome. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. The concomitant use of opioids with other drugs that affect the serotonergic neurotransmitter system has resulted in serotonin syndrome.
    Nilotinib: (Major) The concomitant use of nilotinib and tramadol may reduce the clearance of tramadol and increase the risk for serious adverse events including seizures and serotonin syndrome. If coadministration of these drugs is required, consider reducing the dose of tramadol and monitor patients for signs of toxicity. Nilotinib is a moderate CYP3A4 inhibitor and tramadol is a CYP3A4 substrate.
    Nitroglycerin: (Minor) Nitroglycerin can cause hypotension. This action may be additive with other agents that can cause hypotension such as opiate agonists. Patients should be monitored more closely for hypotension if nitroglycerin is used concurrently with opiate agonists.
    Non-Ionic Contrast Media: (Major) Tramadol lowers the seizure threshold and should be discontinued at least 48 hours before myelography and should not be resumed for at least 24 hours postprocedure.
    Norethindrone Acetate; Ethinyl Estradiol; Ferrous fumarate: (Moderate) Acetaminophen may increase plasma ethinyl estradiol levels, possibly by inhibition of conjugation. Patients taking acetaminophen concomitantly may experience an increase in estrogen related side effects.
    Norethindrone; Ethinyl Estradiol: (Moderate) Acetaminophen may increase plasma ethinyl estradiol levels, possibly by inhibition of conjugation. Patients taking acetaminophen concomitantly may experience an increase in estrogen related side effects.
    Norethindrone; Ethinyl Estradiol; Ferrous fumarate: (Moderate) Acetaminophen may increase plasma ethinyl estradiol levels, possibly by inhibition of conjugation. Patients taking acetaminophen concomitantly may experience an increase in estrogen related side effects.
    Norgestimate; Ethinyl Estradiol: (Moderate) Acetaminophen may increase plasma ethinyl estradiol levels, possibly by inhibition of conjugation. Patients taking acetaminophen concomitantly may experience an increase in estrogen related side effects.
    Odevixibat: (Moderate) Monitor for reduced efficacy of tramadol and signs of opioid withdrawal if coadministration with odevixibat is necessary; consider increasing the dose of tramadol as needed. If odevixibat is discontinued, consider a dose reduction of tramadol and frequently monitor for seizures, serotonin syndrome, and signs of respiratory depression and sedation. Tramadol is a CYP3A substrate and odevixibat is a weak CYP3A inducer. Concomitant use with CYP3A inducers can decrease tramadol levels; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence.
    Olanzapine: (Moderate) If concomitant use of tramadol and olanzapine is warranted, monitor patients for seizures, excessive sedation and/or somnolence, and the emergence of serotonin syndrome. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. Concomitant use of tramadol and olanzapine may increase seizure risk and cause additive CNS depression. The concomitant use of opioids with other drugs that affect the serotonergic neurotransmitter system has resulted in serotonin syndrome.
    Olanzapine; Fluoxetine: (Moderate) Because of the potential risk and severity of serotonin syndrome or neuroleptic malignant syndrome-like reactions, caution should be observed when administering selective serotonin reuptake inhibitors (SSRIs) with other drugs that have serotonergic properties such as tramadol. Several cases of serotonin syndrome have been reported after the administration of tramadol with a SSRI. Concomitant use of tramadol also increases the seizure risk in patients taking selective serotonin reuptake inhibitors (SSRIs). Post-marketing reports implicate the concurrent use of SSRIs with tramadol in some cases of seizures. Lastly, SSRIs such as fluoxetine may inhibit the formation of the active M1 metabolite of tramadol by inhibiting CYP2D6. The inhibition of this metabolite may decrease the analgesic effectiveness of tramadol but increase the level of the parent compound, which has more serotonergic activity than the metabolite. Patients receiving tramadol in combination with an SSRI should be monitored for the emergence of serotonin syndrome, neuroleptic malignant syndrome-like reactions, or other adverse effects. (Moderate) If concomitant use of tramadol and olanzapine is warranted, monitor patients for seizures, excessive sedation and/or somnolence, and the emergence of serotonin syndrome. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. Concomitant use of tramadol and olanzapine may increase seizure risk and cause additive CNS depression. The concomitant use of opioids with other drugs that affect the serotonergic neurotransmitter system has resulted in serotonin syndrome.
    Olanzapine; Samidorphan: (Contraindicated) Salmidorphan is contraindicated in patients who are using opiate agonists or undergoing acute opioid withdrawal. Salmidorphan increases the risk of precipitating acute opioid withdrawal in patients dependent on opioids. Before initiating salmidorphan, there should be at least a 7-day opioid-free interval from the last use of short-acting opioids, and at least a 14-day opioid-free interval from the last use of long-acting opioids. In emergency situations, if a salmidorphan-treated patient requires opiates for anesthesia or analgesia, discontinue salmidorphan. The opiate agonist should be administered by properly trained individual(s), and the patient properly monitored in a setting equipped and staffed for cardiopulmonary resuscitation. In non-emergency situations, if a salmidorphan-treated patient requires opiate agonist treatment (e.g., for analgesia) discontinue salmidorphan at least 5 days before opioid treatment. Salmidorphan, as an opioid antagonist, may cause opioid treatment to be less effective or ineffective shortly after salmidorphan discontinuation. (Moderate) If concomitant use of tramadol and olanzapine is warranted, monitor patients for seizures, excessive sedation and/or somnolence, and the emergence of serotonin syndrome. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. Concomitant use of tramadol and olanzapine may increase seizure risk and cause additive CNS depression. The concomitant use of opioids with other drugs that affect the serotonergic neurotransmitter system has resulted in serotonin syndrome.
    Oliceridine: (Major) Concomitant use of oliceridine with tramadol may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of oliceridine with tramadol to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Also monitor patients for the emergence of serotonin syndrome. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. The concomitant use of opioids with other drugs that affect the serotonergic neurotransmitter system has resulted in serotonin syndrome.
    Olmesartan; Amlodipine; Hydrochlorothiazide, HCTZ: (Moderate) Consider a tramadol dosage reduction until stable drug effects are achieved if coadministration with amlodipine is necessary. Closely monitor for seizures, serotonin syndrome, and signs of sedation and respiratory depression. Respiratory depression from increased tramadol exposure may be fatal. Concurrent use of amlodipine, a weak CYP3A4 inhibitor, may increase tramadol exposure and result in greater CYP2D6 metabolism thereby increasing exposure to the active metabolite M1, which is a more potent mu-opioid agonist. (Moderate) Monitor for decreased diuretic efficacy and additive orthostatic hypotension when thiazide diuretics are administered with tramadol. Adjustments to diuretic therapy may be needed in some patients. The efficacy of diuretics may be reduced due to opioid-induced release of antidiuretic hormone.
    Olmesartan; Hydrochlorothiazide, HCTZ: (Moderate) Monitor for decreased diuretic efficacy and additive orthostatic hypotension when thiazide diuretics are administered with tramadol. Adjustments to diuretic therapy may be needed in some patients. The efficacy of diuretics may be reduced due to opioid-induced release of antidiuretic hormone.
    Ombitasvir; Paritaprevir; Ritonavir: (Major) Tramadol is primarily metabolized by CYP2D6 and CYP3A4; drugs that inhibit these enzymes, such as ritonavir, may decrease the metabolism of tramadol. This may result in a decreased concentration of the active metabolite (O-desmethyltramadol) leading to decreased analgesic effects and possibly increased side effects (seizures and serotonin syndrome) due to higher tramadol concentrations. (Moderate) Concurrent administration of acetaminophen with ritonavir may result in elevated acetaminophen plasma concentrations and subsequent adverse events. Acetaminophen is metabolized by the hepatic isoenzyme CYP3A4; ritonavir is an inhibitor of this enzyme. Caution and close monitoring are advised if these drugs are administered together.
    Omeprazole; Amoxicillin; Rifabutin: (Moderate) As a cytochrome P450 isoenzyme inducers, rifabutin could induce the metabolism of acetaminophen. An increase in acetaminophen-induced hepatotoxicity may be seen by increasing the metabolism of acetaminophen to its toxic metabolite, NAPQI. Also, the analgesic activity of acetaminophen may be reduced.
    Omeprazole; Sodium Bicarbonate: (Minor) Antacids can delay the oral absorption of acetaminophen, but the interactions are not likely to be clinically significant as the extent of acetaminophen absorption is not appreciably affected.
    Ondansetron: (Moderate) If concomitant use of tramadol and ondansetron is warranted, monitor patients for opioid withdrawal and the emergence of serotonin syndrome. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. The concomitant use of opioids with other drugs that affect the serotonergic neurotransmitter system has resulted in serotonin syndrome. Also, data from 2 small trials indicate that concomitant use of ondansetron may result in reduced analgesic activity of tramadol; patients receiving concomitant ondansetron self-administered tramadol more frequently in these trials, leading to an increased cumulative dose in patient-controlled administration (PCA) of tramadol.
    Oritavancin: (Moderate) Tramadol is metabolized by CYP3A4 and CYP2D6; oritavancin is a weak CYP3A4 and CYP2D6 inducer. Plasma concentrations and efficacy of tramadol may be reduced if these drugs are administered concurrently.
    Orphenadrine: (Major) Concomitant use of tramadol with a skeletal muscle relaxant may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medications with a skeletal muscle relaxant to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Osilodrostat: (Moderate) Consider a tramadol dosage reduction until stable drug effects are achieved if coadministration with osilodrostat is necessary. Closely monitor for seizures, serotonin syndrome, and signs of sedation and respiratory depression. Respiratory depression from increased tramadol exposure may be fatal. Concurrent use of osilodrostat, a weak CYP3A4 inhibitor, may increase tramadol exposure and result in greater CYP2D6 metabolism thereby increasing exposure to the active metabolite M1, which is a more potent mu-opioid agonist.
    Oxazepam: (Major) Concomitant use of opiate agonists with benzodiazepines may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opiate pain medications with benzodiazepines to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If an opiate agonist is initiated in a patient taking a benzodiazepine, use a lower initial dose of the opiate and titrate to clinical response. If a benzodiazepine is prescribed for an indication other than epilepsy in a patient taking an opiate agonist, use a lower initial dose of the benzodiazepine and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Oxybutynin: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when tramadol is used concomitantly with an anticholinergic drug. The concomitant use of tramadol and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Oxycodone: (Major) Concomitant use of tramadol increases the seizure risk in patients taking opiate agonists. Also, tramadol can cause additive CNS depression and respiratory depression when used with opiate agonists; avoid concurrent use whenever possible. If used together, extreme caution is needed, and a reduced tramadol dose is recommended.
    Oxymorphone: (Major) Tramadol can cause additive CNS depression and respiratory depression when used with opiate agonists such as oxymorphone. Concomitant use of tramadol and opiate agonists may also increase the risk of seizures; avoid concurrent use whenever possible. Hypotension, profound sedation, coma, respiratory depression, or death may occur. Prior to concurrent use of oxymorphone in patients taking a CNS depressant, assess the level of tolerance to CNS depression that has developed, the duration of use, and the patient's overall response to treatment. Consider the patient's use of alcohol or illicit drugs. If a CNS depressant is used concurrently with oxymorphone, a reduced dosage of oxymorphone (1/3 to 1/2 of the usual dose) and/or the CNS depressant is recommended. If the extended-release oxymorphone tablets are used concurrently with a CNS depressant, it is recommended to use an initial dosage of 5 mg PO every 12 hours. Monitor for sedation or respiratory depression.
    Ozanimod: (Contraindicated) Do not use tramadol in patients taking MAOIs or within 14 days of stopping them. An active metabolite of ozanimod inhibits MAO-B. MAO inhibitor interactions with tramadol may manifest as serotonin syndrome, hypertensive crisis, or opioid toxicity (e.g., respiratory depression, coma). An active metabolite of ozanimod inhibits MAO-B. Although a small number of patients treated with ozanimod were concomitantly exposed to opioids, this exposure was not adequate to rule out the possibility of an adverse reaction from coadministration.
    Palbociclib: (Moderate) If coadministration of palbociclib is necessary, monitor for increased tramadol-related adverse effects (e.g., seizures, serotonin syndrome and opioid toxicity including potentially fatal respiratory depression). Consider a tramadol dose reduction until stable drug effects are achieved. If palbociclib is discontinued, monitor for opioid withdrawal symptoms and consider increasing the tramadol dose. Coadministration of palbociclib, a weak time-dependent CYP3A4 inhibitor, may increase tramadol plasma concentrations and may result in increased metabolism of tramadol through 2D6 resulting in higher levels of the active metabolite, M1.
    Paliperidone: (Moderate) Concurrent use of tramadol and paliperidone should be administered with caution. Antipsychotics, such as paliperidone, may enhance the seizure risk of tramadol. Additive CNS depression may also be seen with the concomitant use of tramadol and paliperidone.
    Palonosetron: (Moderate) If concomitant use of tramadol and palonosetron is warranted, monitor patients for the emergence of serotonin syndrome. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. The concomitant use of opioids with other drugs that affect the serotonergic neurotransmitter system has resulted in serotonin syndrome.
    Panobinostat: (Major) Avoid the concomitant use of panobinostat and tramadol as increased tramadol levels and an increased risk of adverse effects may occur if these agents are used together. If concomitant use cannot be avoided, closely monitor patients for signs and symptoms of tramadol toxicity including seizures and serotonin syndrome. Panobinostat is a CYP2D6 inhibitor and tramadol is primarily metabolized by CYP2D6. When a single-dose of a CYP2D6-sensitive substrate was administered after 3 doses of panobinostat (20 mg given on days 3, 5, and 8), the CYP2D6 substrate Cmax increased by 20% to 200% and the AUC value increased by 20% to 130% in 14 patients with advanced cancer; exposure was highly variable (coefficient of variance > 150%).
    Paroxetine: (Moderate) Patients receiving tramadol in combination with an SSRI should be monitored for the emergence of serotonin syndrome, neuroleptic malignant syndrome-like reactions, seizures, and decreased analgesic effect of tramadol. Several cases of serotonin syndrome have been reported after the administration of tramadol with a SSRI. Symptoms may occur hours to days after concomitant use, particularly after dose increases. Serotonin syndrome may occur within recommended dose ranges. Inform patients taking this combination of the possible increased risk and monitor for the emergence of serotonin syndrome. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. Post-marketing reports also implicate the concurrent use of SSRIs with tramadol in some cases of seizures. Paroxetine may also inhibit the formation of the active M1 metabolite of tramadol by inhibiting CYP2D6. The inhibition of this metabolite may decrease the analgesic effectiveness of tramadol but increase the level of the parent compound, which has more serotonergic activity than the metabolite.
    Pazopanib: (Moderate) Pazopanib is a weak inhibitor of CYP3A4. Coadministration of pazopanib and tramadol, a CYP3A4 substrate, may cause an increase in systemic concentrations of tramadol. Use caution when administering these drugs concomitantly.
    Peginterferon Alfa-2b: (Moderate) Monitor for adverse effects associated with increased exposure to tramadol if peginterferon alfa-2b is coadministered. Peginterferon alfa-2b is a CYP2D6 inhibitor, while tramadol is a CYP2D6 substrate.
    Pegvisomant: (Moderate) In clinical trials, patients taking opiate agonists often required higher serum pegvisomant concentrations to achieve appropriate IGF-I suppression compared with patients not receiving opiate agonists. The mechanism of this interaction is unknown.
    Penicillin G Benzathine; Penicillin G Procaine: (Moderate) Coadministration of penicillin G procaine with oxidizing agents, such as acetaminophen, may increase the risk of developing methemoglobinemia. Monitor patients closely for signs and symptoms of methemoglobinemia if coadministration is necessary. If methemoglobinemia occurs or is suspected, discontinue penicillin G procaine and any other oxidizing agents. Depending on the severity of symptoms, patients may respond to supportive care; more severe symptoms may require treatment with methylene blue, exchange transfusion, or hyperbaric oxygen.
    Penicillin G Procaine: (Moderate) Coadministration of penicillin G procaine with oxidizing agents, such as acetaminophen, may increase the risk of developing methemoglobinemia. Monitor patients closely for signs and symptoms of methemoglobinemia if coadministration is necessary. If methemoglobinemia occurs or is suspected, discontinue penicillin G procaine and any other oxidizing agents. Depending on the severity of symptoms, patients may respond to supportive care; more severe symptoms may require treatment with methylene blue, exchange transfusion, or hyperbaric oxygen.
    Pentazocine: (Major) Avoid the concomitant use of pentazocine and opiate agonists, such as tramadol. Pentazocine is a mixed opiate agonist/antagonist that may block the effects of opiate agonists and reduce analgesic effects. Pentazocine may cause withdrawal symptoms in patients receiving chronic opiate agonists. There is also a potential increased risk of seizures if tramadol and pentazocine are given concurrently. Concurrent use of pentazocine with other opiate agonists can cause additive CNS, respiratory, and hypotensive effects. The additive or antagonistic effects are dependent upon the dose of the opiate agonist used; antagonistic effects are more common at low to moderate doses of the opiate agonist.
    Pentazocine; Naloxone: (Major) Avoid the concomitant use of pentazocine and opiate agonists, such as tramadol. Pentazocine is a mixed opiate agonist/antagonist that may block the effects of opiate agonists and reduce analgesic effects. Pentazocine may cause withdrawal symptoms in patients receiving chronic opiate agonists. There is also a potential increased risk of seizures if tramadol and pentazocine are given concurrently. Concurrent use of pentazocine with other opiate agonists can cause additive CNS, respiratory, and hypotensive effects. The additive or antagonistic effects are dependent upon the dose of the opiate agonist used; antagonistic effects are more common at low to moderate doses of the opiate agonist.
    Pentobarbital: (Major) Concomitant use of tramadol with barbiturates may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medications with barbiturates to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation. Additionally, concomitant use of tramadol with a barbiturate can decrease tramadol concentrations; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence. Monitor for reduced efficacy of tramadol and signs of opioid withdrawal. Discontinuation of a barbiturate may increase the risk of seizures, serotonin syndrome, and the risk of opioid-related adverse reactions, such as fatal respiratory depression. Barbiturates induce CYP3A4; tramadol is a CYP3A4 substrate. (Minor) Chronic therapy with barbiturates can increase the metabolism and decrease the effectiveness of acetaminophen. During acute overdoses, barbiturates can enhance the formation of toxic acetaminophen metabolites.
    Perampanel: (Moderate) Concomitant use of opioid agonists with perampanel may cause excessive sedation and somnolence. Limit the use of opioid pain medications with perampanel to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. Educate patients about the risks and symptoms of excessive CNS depression.
    Perindopril; Amlodipine: (Moderate) Consider a tramadol dosage reduction until stable drug effects are achieved if coadministration with amlodipine is necessary. Closely monitor for seizures, serotonin syndrome, and signs of sedation and respiratory depression. Respiratory depression from increased tramadol exposure may be fatal. Concurrent use of amlodipine, a weak CYP3A4 inhibitor, may increase tramadol exposure and result in greater CYP2D6 metabolism thereby increasing exposure to the active metabolite M1, which is a more potent mu-opioid agonist.
    Perphenazine: (Major) Seizures have been reported in patients receiving monotherapy with tramadol or antipsychotics at recommended doses. Concomitant use of tramadol and antipsychotics may increase the risk of seizures and result in other additive CNS effects. The manufacturer of tramadol cautions that serotonin syndrome may occur during use of drugs that impair the metabolism of tramadol such as CYP2D6 inhibitors, including antipsychotics like perphenazine. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. The analgesic activity of tramadol is due to the activity of both the parent drug and the O-desmethyltramadol metabolite (M1), and M1 formation is dependent on CYP2D6. Therefore, use of tramadol with a CYP2D6 inhibitor may in theory also decrease tramadol efficacy.
    Perphenazine; Amitriptyline: (Major) Seizures have been reported in patients receiving monotherapy with tramadol or antipsychotics at recommended doses. Concomitant use of tramadol and antipsychotics may increase the risk of seizures and result in other additive CNS effects. The manufacturer of tramadol cautions that serotonin syndrome may occur during use of drugs that impair the metabolism of tramadol such as CYP2D6 inhibitors, including antipsychotics like perphenazine. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. The analgesic activity of tramadol is due to the activity of both the parent drug and the O-desmethyltramadol metabolite (M1), and M1 formation is dependent on CYP2D6. Therefore, use of tramadol with a CYP2D6 inhibitor may in theory also decrease tramadol efficacy.
    Pexidartinib: (Moderate) Monitor for reduced efficacy of tramadol and signs of opioid withdrawal if coadministration with pexidartinib is necessary; consider increasing the dose of tramadol as needed. If pexidartinib is discontinued, consider a dose reduction of tramadol and frequently monitor for seizures, serotonin syndrome, and signs of respiratory depression and sedation. Tramadol is a CYP3A4 substrate and pexidartinib is a moderate CYP3A4 inducer. Concomitant use with CYP3A4 inducers can decrease tramadol concentrations; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence.
    Phenobarbital: (Major) Concomitant use of tramadol with barbiturates may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medications with barbiturates to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation. Additionally, concomitant use of tramadol with a barbiturate can decrease tramadol concentrations; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence. Monitor for reduced efficacy of tramadol and signs of opioid withdrawal. Discontinuation of a barbiturate may increase the risk of seizures, serotonin syndrome, and the risk of opioid-related adverse reactions, such as fatal respiratory depression. Barbiturates induce CYP3A4; tramadol is a CYP3A4 substrate. (Minor) Chronic therapy with barbiturates can increase the metabolism and decrease the effectiveness of acetaminophen. During acute overdoses, barbiturates can enhance the formation of toxic acetaminophen metabolites.
    Phenobarbital; Hyoscyamine; Atropine; Scopolamine: (Major) Concomitant use of tramadol with barbiturates may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medications with barbiturates to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation. Additionally, concomitant use of tramadol with a barbiturate can decrease tramadol concentrations; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence. Monitor for reduced efficacy of tramadol and signs of opioid withdrawal. Discontinuation of a barbiturate may increase the risk of seizures, serotonin syndrome, and the risk of opioid-related adverse reactions, such as fatal respiratory depression. Barbiturates induce CYP3A4; tramadol is a CYP3A4 substrate. (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when tramadol is used concomitantly with an anticholinergic drug. The concomitant use of tramadol and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect. (Minor) Chronic therapy with barbiturates can increase the metabolism and decrease the effectiveness of acetaminophen. During acute overdoses, barbiturates can enhance the formation of toxic acetaminophen metabolites.
    Phentermine; Topiramate: (Moderate) Topiramate may contribute to the CNS depression seen with tramadol; tramadol may also decrease the seizure threshold in some patients and thus, potentially, interfere with the ability of anticonvulsants to control seizures.
    Phenytoin: (Major) Tramadol may decrease the seizure threshold in some patients and thus potentially interfere with the ability of anticonvulsants to control seizures. The use of tramadol in patients on anticonvulsant medications for seizure therapy is not recommended. In addition, the hepatic metabolism of tramadol may be accelerated by the use of ethotoin, phenytoin, or fosphenytoin.
    Pimozide: (Major) Concurrent use of tramadol and pimozide should be avoided if possible. Antipsychotics may enhance the seizure risk of tramadol. Additive CNS depression may also be seen with the concomitant use of tramadol and pimozide.
    Pneumococcal Vaccine, Polyvalent: (Moderate) Concomitant administration of antipyretics, such as acetaminophen, may decrease an individual's immunological response to the pneumococcal vaccine. A post-marketing study conducted in Poland using a non-US vaccination schedule (2, 3, 4, and 12 months of age) evaluated the impact of prophylactic oral acetaminophen on antibody responses to Prevnar 13. Data show that acetaminophen, given at the time of vaccination and then dosed at 6 to 8 hour intervals for 3 doses on a scheduled basis, reduced the antibody response to some serotypes after the third dose of Prevnar 13 when compared to the antibody responses of infants who only received antipyretics 'as needed' for treatment. However, reduced antibody responses were not observed after the fourth dose of Prevnar 13 with prophylactic acetaminophen.
    Posaconazole: (Major) Consider a tramadol dosage reduction until stable drug effects are achieved if coadministration with posaconazole is necessary. Closely monitor for seizures, serotonin syndrome, and signs of sedation and respiratory depression. Respiratory depression from increased tramadol exposure may be fatal. Concurrent use of posaconazole, a strong CYP3A4 inhibitor, may increase tramadol exposure and result in greater CYP2D6 metabolism thereby increasing exposure to the active metabolite M1, which is a more potent mu-opioid agonist. (Moderate) Posaconazole and acetaminophen should be coadministered with caution due to an increased potential for acetaminophen-related adverse events. Posaconazole is a potent inhibitor of CYP3A4, an isoenzyme partially responsible for the metabolism of acetaminophen. These drugs used in combination may result in elevated acetaminophen plasma concentrations, causing an increased risk for acetaminophen-related adverse events.
    Pramipexole: (Major) Concomitant use of opioid agonists with pramipexole may cause excessive sedation and somnolence. Limit the use of opioid pain medications with pramipexole to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. Educate patients about the risks and symptoms of excessive CNS depression. Dopaminergic agents like pramipexole have also been associated with sudden sleep onset during activities of daily living such as driving, which has resulted in accidents in some cases. Prescribers should re-assess patients for drowsiness or sleepiness regularly throughout treatment, especially since events may occur well after the start of treatment.
    Pramlintide: (Major) Pramlintide slows gastric emptying and the rate of nutrient delivery to the small intestine. Medications with the potential to slow GI motility, such as opiate agonists, should be used with caution, if at all, with pramlintide until more data are available from the manufacturer. Monitor blood glucose. (Minor) Because pramlintide has the potential to delay the absorption of concomitantly administered medications, medications should be administered at least 1 hour before or 2 hours after pramlintide injection when the rapid onset of a concomitantly administered oral medication is a critical determinant of effectiveness (i.e., analgesics).
    Prasugrel: (Moderate) Consider the use of a parenteral anti-platelet agent for patients with acute coronary syndrome who require concomitant opioid agonists. Coadministration of opioid agonists with prasugrel delays and reduces the absorption of prasugrel's active metabolite due to slowed gastric emptying.
    Pregabalin: (Major) Concomitant use of opioid agonists with pregabalin may cause excessive sedation, somnolence, and respiratory depression. Limit the use of opioid pain medications with pregabalin to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, initiate pregabalin at the lowest recommended dose and monitor patients for symptoms of respiratory depression and sedation. Use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. Educate patients about the risks and symptoms of excessive CNS depression and respiratory depression.
    Prilocaine: (Moderate) Coadministration of prilocaine with oxidizing agents, such as acetaminophen, may increase the risk of developing methemoglobinemia. Monitor patients closely for signs and symptoms of methemoglobinemia if coadministration is necessary. If methemoglobinemia occurs or is suspected, discontinue prilocaine and any other oxidizing agents. Depending on the severity of symptoms, patients may respond to supportive care; more severe symptoms may require treatment with methylene blue, exchange transfusion, or hyperbaric oxygen.
    Prilocaine; Epinephrine: (Moderate) Coadministration of prilocaine with oxidizing agents, such as acetaminophen, may increase the risk of developing methemoglobinemia. Monitor patients closely for signs and symptoms of methemoglobinemia if coadministration is necessary. If methemoglobinemia occurs or is suspected, discontinue prilocaine and any other oxidizing agents. Depending on the severity of symptoms, patients may respond to supportive care; more severe symptoms may require treatment with methylene blue, exchange transfusion, or hyperbaric oxygen.
    Primidone: (Major) Concomitant use of tramadol with barbiturates may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opioid pain medications with barbiturates to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, reduce initial dosage and titrate to clinical response; use the lowest effective doses and minimum treatment durations. Educate patients about the risks and symptoms of respiratory depression and sedation. Additionally, concomitant use of tramadol with a barbiturate can decrease tramadol concentrations; this may result in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence. Monitor for reduced efficacy of tramadol and signs of opioid withdrawal. Discontinuation of a barbiturate may increase the risk of seizures, serotonin syndrome, and the risk of opioid-related adverse reactions, such as fatal respiratory depression. Barbiturates induce CYP3A4; tramadol is a CYP3A4 substrate. (Minor) Chronic therapy with barbiturates can increase the metabolism and decrease the effectiveness of acetaminophen. During acute overdoses, barbiturates can enhance the formation of toxic acetaminophen metabolites.
    Procarbazine: (Major) Avoid use of tramadol concurrently or within 14 days of discontinuing a drug with monamine oxidase inhibitor (MAOI)-like activity, such as procarbazine. If concomitant treatment is clinically warranted, careful observation of the patient is advised, especially during treatment initiation and dose increases. International recommendations contraindicate the use of tramadol within 14 days of an MAOI. There is an increased risk of seizures and serotonin syndrome in patients receiving these drugs currently. In animal studies, an increased number of deaths was noted with the combination due to interference with detoxification mechanisms.
    Prochlorperazine: (Moderate) Concurrent use of tramadol and prochlorperazine should be avoided if possible. Antipsychotics may enhance the seizure risk of tramadol. Additive CNS depression may also be seen with the concomitant use of tramadol and prochlorperazine.
    Promethazine: (Moderate) Caution is advisable during concurrent use of tramadol and promethazine. Seizures have been reported in patients receiving monotherapy with both tramadol and promethazine at recommended doses. Concomitant use of tramadol and promethazine may increase the risk of seizures. In addition, due to the primary CNS effects of promethazine, caution is advisable during use of other centrally acting medications such as tramadol. Impairment of metabolism of tramadol by CYP2D6 inhibitors, such as promethazine, may increase the risk of serotonin syndrome. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. The analgesic activity of tramadol is due to the activity of both the parent drug and the O-desmethyltramadol metabolite (M1), and M1 formation is dependent on CYP2D6. Therefore, use of tramadol with a CYP2D6 inhibitor may decrease tramadol analgesic efficacy.
    Promethazine; Dextromethorphan: (Moderate) Caution is advisable during concurrent use of tramadol and promethazine. Seizures have been reported in patients receiving monotherapy with both tramadol and promethazine at recommended doses. Concomitant use of tramadol and promethazine may increase the risk of seizures. In addition, due to the primary CNS effects of promethazine, caution is advisable during use of other centrally acting medications such as tramadol. Impairment of metabolism of tramadol by CYP2D6 inhibitors, such as promethazine, may increase the risk of serotonin syndrome. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. The analgesic activity of tramadol is due to the activity of both the parent drug and the O-desmethyltramadol metabolite (M1), and M1 formation is dependent on CYP2D6. Therefore, use of tramadol with a CYP2D6 inhibitor may decrease tramadol analgesic efficacy.
    Promethazine; Phenylephrine: (Moderate) Caution is advisable during concurrent use of tramadol and promethazine. Seizures have been reported in patients receiving monotherapy with both tramadol and promethazine at recommended doses. Concomitant use of tramadol and promethazine may increase the risk of seizures. In addition, due to the primary CNS effects of promethazine, caution is advisable during use of other centrally acting medications such as tramadol. Impairment of metabolism of tramadol by CYP2D6 inhibitors, such as promethazine, may increase the risk of serotonin syndrome. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death. The analgesic activity of tramadol is due to the activity of both the parent drug and the O-desmethyltramadol metabolite (M1), and M1 formation is dependent on CYP2D6. Therefore, use of tramadol with a CYP2D6 inhibitor may decrease tramadol analgesic efficacy.
    Propafenone: (Moderate) As propafenone is a moderate CYP2D6 inhibitor and tramadol is primarily metabolized by CYP2D6 and CYP3A4, concurrent therapy may decrease tramadol metabolism. The analgesic activity of tramadol is due to the activity of both the parent drug and the O-desmethyltramadol metabolite (M1), and M1 formation is dependent on CYP2D6. Decreased analgesia might occur. Inhibition of either CYP2D6 and/or CYP3A4 is also expected to reduce the metabolic clearance of tramadol and may increase the risk of tramadol-related adverse events including serotonin syndrome and seizures. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death.
    Propantheline: (Moderate) Monitor patients for signs of urinary retention or reduced gastric motility when tramadol is used concomitantly with an anticholinergic drug. The concomitant use of tramadol and anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Opiates increase the tone and decrease the propulsive contractions of the smooth muscle of the gastrointestinal tract. Prolongation of the gastrointestinal transit time may be the mechanism of the constipating effect.
    Propoxyphene: (Major) As propoxyphene is a moderate CYP2D6 inhibitor and tramadol is primarily metabolized by CYP2D6 (and CYP3A4), concurrent therapy may decrease tramadol metabolism. This interaction may result in decreased tramadol efficacy and/or increased tramadol-induced risks of serotonin syndrome or seizures. The analgesic activity of tramadol is due to the activity of both the parent drug and the O-desmethyltramadol metabolite (M1), and M1 formation is dependent on CYP2D6. Therefore, use of tramadol with a CYP2D6-inhibitor may alter tramadol efficacy. In addition, inhibition of either or both CYP2D6 and CYP3A4 is expected to result in reduced metabolic clearance of tramadol. This in turn may increase the risk of tramadol-related adverse events including serotonin syndrome and seizures. Serotonin syndrome is characterized by rapid development of hyperthermia, hypertension, myoclonus, rigidity, autonomic instability, mental status changes (e.g., delirium or coma), and in rare cases, death.
    Propranolol; Hydrochlorothiazide, HCTZ: (Moderate) Monitor for decreased diuretic efficacy and additive orthostatic hypotension when thiazide diuretics are administered with tramadol. Adjustments to diuretic therapy may be needed in some patients. The efficacy of diuretics may be reduced due to opioid-induced release of antidiuretic hormone.
    Pseudoephedrine; Triprolidine: (Moderate) Concomitant use of opioid agonists with triprolidine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with triprolidine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Pyrilamine: (Moderate) Concomitant use of opioid agonists with pyrilamine may cause excessive sedation and somnolence. Limit the use of opioid pain medication with pyrilamine to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect.
    Quazepam: (Major) Concomitant use of opiate agonists with benzodiazepines may cause respiratory depression, hypotension, profound sedation, and death. Limit the use of opiate pain medications with benzodiazepines to only patients for whom alternative treatment options are inadequate. If concurrent use is necessary, use the lowest effective doses and minimum treatment durations needed to achieve the desired clinical effect. If an opiate agonist is initiated in a patient taking a benzodiazepine, use a lower initial dose of the opiate and titrate to clinical response. If a benzodiazepine is prescribed for an indication other than epilepsy in a patient taking an opiate agonist, use a lower initial dose of the benzodiazepine and titrate to clinical response. Educate patients about the risks and symptoms of respiratory depression and sedation.
    Quetiapine: (Moderate) If concomitant use of tramadol and quetiapine is warranted, monitor patients for seizures, excessive sedation and/or somnolence, and the emergence of serotonin syndrome. Discontinue all serotonergic agents and initiate symptomatic treatment if serotonin syndrome occurs. Concomitant use of tramadol and quetiapine may increase seizure risk and cause additive CNS depression. The concomitant use of opioids with other drugs that affect the serotonergic neurotransmitter system has resulted in serotonin syndrome.
    Quinapril; Hydrochlorothiazide, HCTZ: (Moderate) Monitor for decreased diuretic efficacy and additive orthostatic hypotension when thiazide diuretics are administered with tramadol. Adjustments to diuretic therapy may be needed in some patients. The efficacy of diuretics may be reduced due to opioid-induced release of antidiuretic hormone.
    Quinidine: (Moderate) As quinidine is a potent inhibitor of CYP2D6 and tramadol is partially metabolized by CYP2D6, concurrent therapy may decrease tramadol metabolism. This interaction may result in decreased tramadol efficacy and/or increased tramadol-induced risks of serotonin syndrome or seizures. The analgesic activity of tramadol is due to the activi