Propylthiouracil is indicated in the medical treatment of hyperthyroidism. Long-term therapy may lead to remission of the disease. Propylthiouracil may also be used to ameliorate hyperthyroidism in preparation for subtotal thyroidectomy or radioactive iodine therapy. Propylthiouracil is also used when thyroidectomy is contraindicated or not advisable.

Currently there are no off label uses for Propylthiouracil.

Agranulocytosis is potentially the most serious side effect of Propylthiouracil therapy. Patients should be instructed to report any symptoms of agranulocytosis, such as fever or sore throat. Leukopenia, thrombocytopenia, and aplastic anemia (pancytopenia) may also occur. The drug should be discontinued in the presence of agranulocytosis, aplastic anemia (pancytopenia), ANCA-positive vasculitis, hepatitis, interstitial pneumonitis, fever or exfoliative dermatitis. The patient’s bone marrow function should be monitored.

Propylthiouracil can cause fetal harm when administered to a pregnant woman. Because the drug readily crosses placental membranes and can induce goiter and even cretinism in the developing fetus, it is important that a sufficient, but not excessive, dose be given. In many pregnant women, the thyroid dysfunction diminishes as the pregnancy proceeds; consequently, a reduction of dosage may be possible. In some instances, Propylthiouracil can be withdrawn 2 or 3 weeks before delivery.

If this drug is used during pregnancy, or if the patient becomes pregnant while taking this drug, the patient should be warned of the potential hazard to the fetus.

Postpartum patients receiving Propylthiouracil should not nurse their babies.

Rare reports exist of severe hepatic reactions including encephalopathy, fulminant hepatic necrosis and death in patients receiving Propylthiouracil. Symptoms suggestive of hepatic dysfunction (anorexia, pruritus, right upper quadrant pain, etc.) should prompt evaluation of liver function. Treatment with Propylthiouracil should be discontinued promptly in the event of clinically significant evidence of liver abnormality, including hepatic transaminases in excess of 3 times the upper limit of normal.