Dermographism: reduction in weal size by chlorpheniramine and hydroxyzine

Regular measurements of the weal size produced by known trauma have been carried out in a series of patients with symptomatic dermographism. The degree of reduction of the weal has been compared after 2 weeks’treatment with chlorpheniramine and hydroxyzine pamoate administered in a double blind manner to thirty-three patients. The doses given were those in common usage and usually well tolerated by patients, namely chlorpheniramine 4 mg three times daily and hydroxyzine pamoate 25 mg three times daily. Hydroxyzine gave a statistically greater reduction of weal size and was also clinically preferred. Hydroxyzine is a weak antihistamine and its mode of action on weal production is unknown, but its clinical efficacy is not likely to be due to its sedative effects. Statistical proof is given to the observation that weals on exposed sites are smaller than those provoked in areas of skin normally covered.