The urticarias. Current concepts in pathogenesis and treatment.

Urticaria is a very common disease which is often associated with angioedema. Release of histamine and perhaps other mediators from the cutaneous mast cells is believed to be the likeliest cause for the development of these wheals in most instances, but there may be both non-immunological as well as immunological inputs into this final common pathway. The former include trauma, cholinergic mechanisms and non-immunological histamine release by drugs. Immune mechanisms most commonly are of the IgE-mediated type, but occasionally the activation of complement or other mediators of hypersensitivity may be involved. Drug and food allergy are among the most common causes of acute urticaria, but there are numerous other possibilities which mandate a thorough general medical history and physical examination (including ruling out infection, connective tissue disease and neoplasms). In cases of chronic urticaria, when the lesions have persisted for longer than about 2 months, no cause for the disease is discernable in most instances. However, in these cases, as well as in acute urticaria, symptomatic treatment generally can provide substantial symptom relief, with emphasis on the astute use of various types of antihistamines.