Combined H1 and H2 antihistamine therapy in chronic urticaria

• Chronic urticaria is a frustrating problem for the patient and the physician. The cause is usually undetermined, and the therapy is directed toward controlling symptoms. Recent evidence that human skin blood vessels possess H₂receptors, as well as the commonly recognized H₁receptors, suggests a possible reason for the frequent failure of H₁antihistamines in controlling this disorder. Eighteen patients with refractory chronic idiopathic urticaria participated in a double-blind, cross-over study to evaluate the efficacy of combined H (hydroxyzine hydrochloride) and H₂(cimetidine) antihistamines vs H₁antihistamines alone. This study indicates that combined H₁and H₂antihistamine therapy is statistically more effective than H¹antihistamines alone in controlling the symptoms of chronic urticaria. (Arch Dermatol1981;117:404-407)