Erythema nodosum caused by omeprazole.

We report a case of erythema nodosum caused by omeprazole. This side effect of omeprazole has not been previously reported. A 35-year-old white woman developed multiple tender erythematous nodules over the anterior aspect of her upper and lower extremities, fever, malaise, and edema. Her symptoms resolved with withdrawal of all preexisting medications and conservative treatment. Her symptoms flared soon after a rechallenge with omeprazole. A thorough history, physical examination, laboratory evaluation, and roentgenogram failed to reveal another cause for erythema nodosum. It is clear from the rechallenge that this patient's erythema nodosum was caused by omeprazole. We consider that omeprazole should be added to the list of medications known to cause erythema nodosum.