Methimazole is a thioamide chemical used therapeutically as an antithyroid agent, given for the palliative treatment of hyperthyroidism and to control thyrotoxic crises that may accompany thy-roidectomy. In humans, methimazole is associated with malformations as described in the package label for the drug. The package label carries a warning that the drug “can cause fetal harm when administered to a pregnant woman.” The label goes on to state that it can induce goiter and even cretinism in the developing fetus, and, in addition, rare instances of congenital defects: aplasia cutis as manifested by scalp defects, esophageal atresia with tracheoesophageal fistula, and choanal atresia with absent/hypoplastic nipples. Lack of effect on intellectual development by the drug was also reported by other investigators. Lack of effect on intellectual development by the drug was also reported by other investigators.