The presentation of 6-mercaptopurine overdose in ED.

6-Mercaptopurine (6-MP), although an effective immunosuppressive when used in the treatment of certain cancers, can have devastating effects when ingested accidentally or used in excessive amounts. We report here the case of an unintentional ingestion of a large amount of 6-MP by a woman with hypothyroidism who was erroneously given this antimetabolic agent by her pharmacist instead the propylthiouracil (PTU) she was actually prescribed. This is one of several documented cases in which 6-MP has been dispensed instead of PTU. Because of the myelosuppressive and hepatotoxic effects of 6-MP, this case reinforces the need for both physicians and patients to understand the importance of examining their medications before ingestion.