Oral zinc in acne vulgaris: a clinical and methodological study.

In a double-blind investigation of 54 patients suffering from acne vulgaris, the effect of 0.6 g of oral zinc sulphate daily versus placebo was studied. During the active treatment period of 6 weeks, the acne improved by about one-third, as rated with a score system. Clinical comparison with placebo showed the result of zinc sulphate therapy to be slightly, but statistically significantly better. Various methods for the clinical evaluation of acne were studied. Counting of acne lesions was found to be a more precise method than assessment according to the opinion of the patients and the assessment of colour photographs. The correlation between the results obtained by lesion counting and evaluation by photographs was low, as was also the reproducibility of photographic assessment.