Terfenadine does not inhibit non-immunologic contact urticaria

To investigate the mechanisms of non-immunologic contact urticaria (NICU), the effect of 120 mg of terfenadine (H1-antagonist) on contact reactions to methyl nicotinate, diethyl fumarate, benzoic acid, cinnamic acid, cinnamic aldehyde and dimethyl sulfoxide was studied in 20 subjects. Erythema and edema were observed visually, and the changes in the skin blood flow were monitored with laser-Doppler flowmetry. Terfenadine did not have any significant inhibitory effect on erythema or edema from 6 contact urticariants tested, but it inhibited erythema and edema of prick test reactions to histamine. Non-specific histamine release from mast cells does not seem to be the mechanism of NICU from these substances.