FDA Drug Safety Communication

FDA is notifying healthcare professionals of the risk of serious liver injury, including liver failure and death, with the use of propylthiouracil in adult and pediatric patients. Reports to the FDA suggest there is an increased risk of hepatotoxicity with when compared to methimazole. Although both propylthiouracil and methimazole are indicated for the treatment of hyperthyroidism due to Graves' disease, healthcare professionals should carefully consider which drug to initiate in a patient recently diagnosed with Graves' disease. Physicians should closely monitor patients on propylthiouracil therapy for symptoms and signs of liver injury, especially during the first 6 months after initiation of therapy.

This information reflects the current analysis of data available to FDA concerning propylthiouracil. Posting this information does not mean that FDA has concluded there is a causal relationship between the drug product and the emerging safety issue. Nor does it mean that FDA is advising healthcare professionals to discontinue prescribing the product. FDA intends to update this communication when additional information or analyses become available.

View the full FDA Drug Safety Communication on FDA.gov