Caffeine as a cause of urticaria-angioedema.

We report the case of a young woman presenting with recurrent urticaria. The episodes occurred both in and out of the workplace. On three occasions it presented as urticaria-angioedema, requiring emergency care on one occassion. A thorough clinical history along with serological and allergological tests allowed a diagnosis of caffeine-induced urticaria-angioedema. We advised the patient to follow a caffeine-free diet and to avoid all caffeine or methylxanthine-containing drugs. After two years of caffeine abstinence, she had not experienced any further episodes of urticaria-angioedema. Only a few cases of caffeine-induced urticaria and/or anaphylaxis have been reported till date, with varying outcomes in allergologic investigations. Moreover, several cases are probably undiagnosed or misdiagnosed as idiopathic urticaria or as occupational allergy. We speculate that hypersensitivity to caffeine rather than autoimmine reaction may be the probable cause of urticaria. Caffeine should considered as a potential urticaria-inducing agent and should be included in the allergological test series.