Vascular reactions to histamine and compound 48/80 in human skin: suppression by a histamine H2‐receptor blocking agent.

1 The ability of a specific competitive histamine H2-receptor antagonist, cimetidine, to inhibit vascular responses to histamine in human skin provides new evidence that skin blood vessels possess histamine H2 receptors. 2 Simultaneous systemic administration of cimetidine and chlorpheniramine (an H1-receptor antagonist) was more effective than either drug alone in inhibition of the erythematous reaction both to exogenous histamine, and endogenous histamine secreted by skin mast cells in response to compound 48/80. 3 These results suggest that combined therapy of histamine-mediated skin diseases included urticaria and dermatitis using a combination of H1- and H2-histamine receptor antagonists may be more effective than either class of drug alone.