The effect of capsaicin on some experimental inflammations in human skin.

Topical application of capsaicin is thought to deplete substance P from local sensory nerve terminals. In experiments on human skin inflammation was induced by injection of substance P (SP) or histamine intradermally, UV irradiation, non-immunologic contact urticaria, tuberculin reaction, contact allergens and benzalkonium chloride with or without capsaicin pretreatment. The flare response to SP and histamine was suppressed by capsaicin pretreatment whereas the wheal was enlarged. Interestingly, capsaicin pretreatment enhanced the responses to all other inflammatory agents.