In search of an improved treatment of pruritic dermatoses, we have studied azelastine, a novel H1-receptor antagonist, during a 2-week treatment period, using a double-blind, placebo-controlled design. The potent H1-antagonist cetirizine was used for comparison. Symptoms were recorded daily by the patients on a diary card, using a 4-point scale. The same parameters and adverse events were evaluated at weekly intervals, and global improvement was evaluated at the end of treatment. In all 230 evaluable patients with moderate to severe itching, azelastine caused an overall significant improvement in comparison to placebo (F=0.02), with significance also for pruritus (P=0.01 after 1 week and P=0.02 after 2 weeks). Both drugs reduced itching more effectively in urticaria than in atopic eczema. Azelastine was superior to cetirizine in reducing pruritus, whereas cetirizine caused a more marked reduction of whealing. Both drugs rarely caused fatigue and dry mouth, but taste perversion occurred only in azelastine-treated patients (9.7%) and headaches only with cetirizine (10.4%). Therefore, the two H, blockers exert differential effects on pruritus verses whealing and a distinctive adverse events pattern. TTie data also underline the low efficacy of antihistamines in atopic eczema, compared to urticaria.