Delayed hypersensitivity reaction to loperamide : An intriguing case report with positive challenge test

Dear Editor, Loperamide hydrochloride (Imodium(R)) is a symptomatic anti-diarrheal agent used for relieving acute and chronic diarrhea. It is an opiate derivative, which has no effects on central nervous system. Loperamide stops diarrhea via its negative effects on intestinal peristalsis and its mild antisecretory properties. Loperamide is generally considered safe, but was in few cases the cause of anaphylaxis. We report the case of a 48 year old female patient, with no relevant past medical or surgical history, who presented to allergy consultation in 2008 for a potential exploration of multiple drug allergy history. The patient described two possible immunemediated allergic reactions that had occurred three years ago before, the first during an upper respiratory tract infection with a delayed generalized urticaria at day five of amoxicillin intake. The second episode was particularly severe and occurred during a gastroenteritis episode. In fact, eight to 10 h after taking diclofenac, paracetamol, pantoprazole and loperamide hydrochloride, she presented generalized urticaria, lips angioedema and dysphagia.