In order to assess the antihistaminic power of cetirizine and ebastine, we designed a randomized, double-blind, crossover study, measuring their capacity to modify skin blood flow induced by a histamine prick test. The vasomotor response was compared using a laser Doppler flowmeter. Two hours after intake of the antihistaminic drug, there were significant differences between both drugs: at 4 h, the antihistaminic effect of cetirizine persists, whereas ebastine only showed moderate activity. The reduction of the cutaneous blood flow values (CBFV) showed good activity in both groups, but cetirizine was more potent and showed faster activity than ebastine.