title: Combined H1 and H2 antihistamine therapy in chronic urticaria.
abstract: 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 H2 receptors, as well as the commonly recognized H1 receptors, suggests a possible reason for the frequent failure of H1 antihistamines 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 H1 (hydroxyzine hydrochloride) and H2 (cimetidine) antihistamines vs H1 antihistamines alone. This study indicates that combined H1 and H2 antihistamine therapy is statistically more effective than H1 antihistamines alone in controlling the symptoms of chronic urticaria.
mesh_terms: D000328:Adult; D000368:Aged; D002908:Chronic Disease; D002927:Cimetidine / Q000627:therapeutic use*; D004311:Double-Blind Method; D004359:Drug Therapy, Combination; D005069:Evaluation Studies as Topic; D005260:Female; D006146:Guanidines / Q000627:therapeutic use*; D006634:Histamine H1 Antagonists / Q000627:therapeutic use; D006635:Histamine H2 Antagonists / Q000627:therapeutic use; D006801:Humans; D006919:Hydroxyzine / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D014581:Urticaria / Q000188:drug therapy*
chemical_list: D006146:Guanidines; D006634:Histamine H1 Antagonists; D006635:Histamine H2 Antagonists; D006919:Hydroxyzine; D002927:Cimetidine