Major adverse reactions to propylthiouracil in 586 cases of hyperthyroidism

Aiming to know the incidence and evolution of major adverse reactions to propylthiouracil in patients with hyperthyroidism, we performed a retrospective analysis of 586 patients treated between 1982 and 1992. All known complications associated to the use of propylthiouracil were considered major adverse reactions, when other causes were discarded. Eight patients (1.4% of the sample) had major adverse reactions: three had agranulocytosis, 3 hepatitis, 1 cholestasis and 1 vasculitis. All had a good evolution after discontinuing the drug. The patients with agranulocytosis were treated with antibiotics and the patient with cholestasis received prednisone. We conclude that major adverse reactions to propylthiouracil are infrequent, that they occur preferentially during the first months of treatment, earlier after reexposure and that there was no associated mortality.