A double-blind cross-over study of the effect of ketotifen in urticaria pigmentosa.

10 adult patients with symptomatic urticaria pigmentosa were treated with ketotifen versus placebo in a double-blind cross-over study. A highly significant reduction of the daily symptom scores for pruritus and whealing was found with 2 mg ketotifen daily per os, and, compared to oral disodium cromoglycate, ketotifen was much more effective. Tiredness was the only side effect noted in 40% of the patients, and a transient worsening of symptoms was noted after discontinuation of the drug.