Propylthiouracil is a thiocarbamide chemical derivative used in the palliative treatment of hyper-thyroidism and in the management of thyrotoxic crises. It is known by its generic name, as well as by the trade name Propyl-Thyracil®, among other names. Propylthiouracil has a pregnancy category of D. If the drug is used during pregnancy, or if the patient becomes pregnant while taking the drug, the patient should be warned of the potential hazard to the fetus. In a number of species, propylthiouracil administered orally to laboratory animals caused thyroid lesions, including enlargement. In humans, propylthiouracil treatment during pregnancy causes suppression of thyroid function in the fetus, and goiter may result as compensation for the induced hypothyroidism. This constitutes a functional deficit with respect to class of developmental toxicity affected. Propylthiouracil is a hydrophobic compound that is smaller than the other human developmental toxicants within this compilation. It is of average polarity.