[Effect of ketotifen in urticaria factitia and urticaria cholinergica in a crossover double-blind trial].

Forty patients with urticaria, 13 with cholinergic urticaria, 22 with urticaria factitia, and 5 with both types of urticaria, were treated with ketotifen or placebo in a double-blind crossover study. Five patients dropped out, one because of excessive weight gain. In 23 of 24 patients with urticaria factitia, ketotifen caused a marked reduction of wealing and pruritus. In contrast, only 62% of the patients with cholinergic urticaria noticed a reduction of wealing, and 69% had reduced itching. Ketotifen caused few side effects, the most frequent one being mild tiredness in 9% of the patients. The beneficial effect of ketotifen in urticaria factitia and cholinergic urticaria may be due to its ability to reduce the liberation and the effectiveness of mast cell mediators.