Effects of alpha-hydroxy acids on photoaged skin: A pilot clinical, histologic, and ultrastructural study

Backgroound: alpha-Hydroxy acids (AHAs) have been reported to improve aging skin. The mechanisms of action of AHAs on epidermal and dermal compartments need clarification. Objective: Our purpose was to determine the effects of AHAs on photoaged human skin by clinical and microanalytic means. Methods: Patients applied a lotion containing 25% glycolic, lactic, or citric acid to one forearm and a placebo lotion to the opposite forearm for an average of 6 months. Thickness of forearm skin was measured throughout the study. Biopsy specimens from both forearms were processed for analysis at the end of the study. Results: Treatment with AHAs caused an approximate 25% increase in skin thickness. The epidermis was thicker and papillary dermal changes included increased thickness, increased acid mucopolysaccharides, improved quality of elastic fibers, and increased density of collagen. No inflammation was evident. Conclusion: Treatment with AHAs produced significant reversal of epidermal and dermal markers of photoaging.