• Severe liver injury and acute liver failure, in some cases requiring liver transplantation or resulting in death, reported in adult and pediatric patients.(See Hepatotoxicity under Cautions.)
• Reserve propylthiouracil for patients who cannot tolerate methimazole and for whom radioactive iodine therapy or surgery are not appropriate for the management of hyperthyroidism. (See Hyperthyroidism under Uses.)
• Propylthiouracil may be the treatment of choice when an antithyroid drug is indicated during or just prior to the first trimester of pregnancy because of the risk of fetal abnormalities associated with methimazole. (See Fetal/Neonatal Morbidity and also see Pregnancy under Cautions.)

REMS:

FDA approved a REMS for propylthiouracil (ptu) to ensure that the benefits of a drug outweigh the risks. However, FDA later rescinded REMS requirements. See the FDA REMS page ([Web]) or the ASHP REMS Resource Center ([Web]).