Urticaria and angioedema.

Urticaria and angioedema are commonly seen in the outpatient setting. Their pathogenesis involves complex cellular and humoral factors. Diagnosis depends on historical information such as duration of symptoms, exacerbating factors, and atopy. While many etiologic factors have been implicated, in most chronic cases no specific etiology is found. This article reviews physical and hereditary syndromes and discusses therapeutic regimens based on the duration and severity of symptoms.