A double-blind, controlled trial of levamisole in the treatment of recurrent herpes labialis.

A double-blind, controlled trial of levamisole in the prevention and treatment of recurrent cold sores was performed. Forty-eight subjects received levamisole in a dosage of 2.5 mg/kg on two consecutive days each week for six months. The 51 control subjects were given a placebo identical to the drug in appearance. Both groups were given the same instructions. Nineteen subjects receiving levamisole and eight receiving placebo withdrew during the six months of the study. There were no significant differences between the levamisole-treated and control groups in the duration or severity of the lesions during the trial period or in the subjective assessment of drug efficacy by the participants at the end of the trial. Before treatment the frequency of lesions in the levamisole group was higher than in the control group. Only when this factor was taken into account by analysis of covariance did the decreased frequency of lesions during therapy appear significantly lower in the group receiving levamisole than in the placebo group. The difference remained clinically unimpressive. This study does not support earlier suggestions that levamisole, in these doses, is useful in the treatment of recrudescent circumoral herpesvirus infections.