Comparison of the effect of glycerol and triamcinolone acetonide on cumulative skin irritation in a randomized trial

Background: So-called anti-irritants are added to cosmetic formulations because of their alleged beneficial effect on irritated skin. Documentation for these claims is often limited. However, glycerol has shown anti-irritant properties in experimentally induced irritation from sodium lauryl sulfate and nonanoic acid (NON). This study was designed to further substantiate that glycerol added to cosmetic formulations has an anti-irritant effect on experimentally induced skin irritation. Objective: We sought to compare glycerol with triamcinolone acetonide as treatments for cutaneous irritation in human volunteers. Methods: Irritation was induced by 3 daily arm washes for a week with 10% sodium lauryl sulfate on one arm and 30% NON on the other. To maintain irritation, for the next 12 days volunteers washed their arms twice daily with the irritants. Treatments were applied immediately after washing. The treatments (including vehicle and no treatment) were randomized to sites using a Latin square design. The reactions were evaluated clinically and instrumentally. Limitations: Study was designed to only detect potent anti-irritants. Conclusion: Glycerol reduced the irritant effect of both sodium lauryl Sulfate and NON, whereas triamcinolone acetonide appeared to have beneficial effect only on the irritation induced by NON. The study provided experimental documentation for the claim that glycerol has anti-irritant effect in a cosmetic formulation.