Capsaicin enhances allergic contact dermatitis in the guinea pig

Guinea pigs were sensitized to dinitrochlorobenzene (DNCB) by the intracutaneous route and challenged epicutaneously on the flanks. The intensity of the allergic contact dermatitis was evaluated by inspection and palpation as well as by wet weight determination. With the purpose of diminishing tissue neuropeptides, and substance P in particular, the animals were treated with capsaicin either between induction and challenge, or before sensitization. In comparison with controls, the contact dermatitis was enhanced in both groups of animals treated with capsaicin.