Recent studies suggest that
histamine H2-receptor antagonists may be useful in the treatment of
urticaria. This study was conducted to determine whether
famotidine, a H2 antagonist, is effective in the treatment of acute
urticaria and compare its effect with that of the H1 antagonist
diphenhydramine. In this prospective, double-blind, controlled trial, 25 patients with
urticaria of less than 72 h duration were randomized to receive a single dose of either
famotidine 20 mg i.m. or
diphenhydramine 50 mg i.m. Prior to treatment and 30 min
after treatment, patients rated
pruritus and sedation using visual analogue scales, while physicians evaluated intensity of
urticaria and percentage of body surface area involved by
urticaria.
Famotidine was found to reduce
pruritus associated with acute
urticaria, intensity of
urticaria, and body surface area affected by
urticaria without causing sedation.
Famotidine was comparable to
diphenhydramine in efficacy; however, there was a (nonsignificant) trend for
diphenhydramine to be more effective than
famotidine in the treatment of
pruritus, and for
famotidine to be more effective in the reduction of surface area of involvement. It is concluded that
famotidine merits further investigation as a potential medication for treatment of
urticaria.