Sudden onset agranulocytosis and hepatotoxicity after taking methimazole

Abstract

Agranulocytosis is a rare adverse effect of methimazole. The usual duration of treatment prior to the onset of agranulocytosis is approximately 1 to 4 months, and can be as long as 1 year. Agranulocytosis together with hepatotoxicity is an extremely rare idiosyncratic side effect of methimazole treatment. We present an unprecedented case of a Grave's disease patient who showed a strong reaction to methimazole with obvious agranulocytosis and hepatotoxicity which developed only six days after administration. This case, along with a literature review, is offered with the aim to increase the awareness of physicians of sudden onset agranulocytosis and hepatotoxicity from methimazole. © 2012 The Japanese Society of Internal Medicine.