Double blind crossover trial of levamisole in recurrent aphthous ulceration.

A double blind crossover trial of levamisole has been carried out in 47 patients with recurrent oral ulceration. Significant decreases in the number of ulcers and ulcer days were found after 2 months of intermittent administration of levamisole. About 64% of patients responded to the drug by a decrease in the number of ulcers of more than 50%, for two or more months. The remaining 36% of patients failed to respond to levamisole and 23% of these had an increased number of ulcers. The side-effects recorded in patients taking levamisole were comparable with those in patients on placebo, except for a flu-like syndrome in 1 patient and urticaria in another, necessitating withdrawal of the drug. The mechanism of action of levamisole in recurrent oral ulceration is not known, but it is suggested that levamisole may correct a deficiency of suppressor cells, or potentiate the cellular responses to crossreacting microbial agents.