Urticaria: evaluation and treatment.

Urticaria involves intensely pruritic, raised wheals, with or without edema of the deeper cutis. It is usually a self-limited, benign reaction, but can be chronic. Rarely, it may represent serious systemic disease or a life-threatening allergic reaction. Urticaria has a lifetime prevalence of approximately 20 percent in the general population. It is caused by immunoglobulin E- and nonimmunoglobulin E-mediated mast cell and basophil release of histamine and other inflammatory mediators. Diagnosis is made clinically. Chronic urticaria is usually idiopathic and requires only a simple laboratory workup unless elements of the history or physical examination suggest specific underlying conditions. Treatment includes avoidance of triggers, although these can be identified in only 10 to 20 percent of patients with chronic urticaria. First-line pharmacotherapy for acute and chronic urticaria is nonsedating second-generation antihistamines (histamine H1 blockers), which can be titrated to larger than standard doses. First-generation antihistamines, histamine H2 blockers, leukotriene receptor antagonists, and brief corticosteroid bursts may be used as adjunctive treatment. More than one-half of patients with chronic urticaria will have resolution or improvement of symptoms within one year.