Propylthiouracil (Propylthiouracil) Endocrine/Metabolic Thyroid drug Hyperthyroidism, overproduction of thyroid hormone by the thyroid gland. 300 mg in 3 divided doses; severe disease requires 400 to 900 mg. Category D Skin rash, upset stomach, vomiting, loss of taste, abnormal loss of hair, headache, drowsiness, agranulocytosis, visual disturbances, vasculitis, altered AST, ALT, hepatotoxicity, dose-related hypothyroidism. Pregnancy Risk Categories defined: A: Studies in pregnant women failed to show a risk to the fetus in the first trimester - with no evidence of risk in the later trimesters. B: Animals studies indicate no adverse effect to the fetus, but there are no adequate, clinical studies in pregnant women. C: Animal studies have shown an adverse effect on the fetus, but there are no adequate, clinical studies in humans. Despite potential risks, the drug may be useful in pregnant women. D: There is evidence of risk to the human fetus, but the potential benefits of use in pregnant women may be acceptable, despite potential risks. X: Studies in animals or humans show fetal abnormalities, or adverse reaction reports indicate evidence of fetal risk. Warning: the risks involved clearly outweigh any potential benefit from using the drug in pregnant women, regardless of trimester. NR: Not rated (i.e., no information available at this time as to the potential risks or benefits).