FDA Drug Safety Communication

FDA has added a Boxed Warning to the label for propylthiouracil, a drug used to treat hyperthyroidism (overactive thyroid), to include information about reports of severe liver injury and acute liver failure, some of which have been fatal, in adult and pediatric patients using this medication.

The new warning also states that for patients being started on treatment for hyperthyroidism, it may be appropriate to reserve use of propylthiouracil for those who cannot tolerate other treatments such as methimazole, radioactive iodine, or surgery. In addition, due to the occurrence of birth defects that have been observed with the use of methimazole during the first trimester of pregnancy, propylthiouracil may be the treatment of choice during and just before the first trimester of pregnancy. Propylthiouracil is not recommended for use in pediatric patients, except in rare instances in which other alternative treatments are not appropriate.

Also, as part of a Risk Evaluation and Mitigation Strategy (REMS), FDA is requiring that a Medication Guide be given to every patient filling a prescription for propylthiouracil.

View the full FDA Drug Safety Communication on FDA.gov