The effects of diethylcarbamazine citrate, antihistamines and corticosteroid derivatives on skin reactivity to Onchocerca supernatants.

A single dose of promethazine or of betamethazone, either alone or compounded with dexchloropheniramine, was found to inhibit skin wheal formation in onchocerciasis patients challenged with Onchocerca supernatants. The mean wheal diameter developing 24 hours after drug administration ranged between 40-60% less than the original pre-treatment diameter but this effect had been abolished or was significantly less by 48 hours. Diethycarbamazinecitrate had only a 20% inhibitory effect on the wheal diameter of the skin reaction. It is concluded that antihistamines and corticosteroid derivates may interfere with the immunodiagnostic skin test for onchocerciasis based on skin reactivity to Onchocerca supernatants, unless measures are taken to ensure that these drugs are not consumed within the 48 hours preceding the skin test.