An evidence-based review of the efficacy of antihistamines in relieving pruritus in atopic dermatitis.

OBJECTIVE To critically review the body of clinical trials that refute or support the efficacy of antihistamines in relieving pruritus in patients with atopic dermatitis. DESIGN Review of MEDLINE from 1966 through March 1999, the Cochrane Database of Systematic Reviews, and Best Evidence to identify therapeutic trials of antihistamines in patients with atopic dermatitis. MAIN OUTCOME MEASURES All randomized controlled trials or clinical trials of antihistamines used in the treatment of atopic dermatitis. We found 16 studies throughout the literature. RESULTS Large, randomized, double-blind, placebo-controlled clinical trials with definitive conclusions (grade A trials) have not been performed. Two grade B trials (small, rigorous, randomized trials with uncertain results due to moderate to high alpha or beta error) refuted the use of antihistamines in relieving pruritus. One grade B trial supported the efficacy of antihistamines in relieving pruritus. All remaining trials (grade C) lacked placebo controls or randomization, or contained fewer than 20 patients in each treatment group. CONCLUSIONS Although antihistamines are often used in the treatment of atopic dermatitis, little objective evidence exists to demonstrate relief of pruritus. The majority of trials are flawed in terms of the sample size or study design. Based on the literature alone, the efficacy of antihistamines remains to be adequately investigated. Anecdotally, sedating antihistamines have sometimes been useful by virtue of their soporific effect and bedtime use may be warranted. There is no evidence to support the effectiveness of expensive nonsedating agents.