A pilot study on the cutaneous effects of ethanol in a moisturizing cream on non-lesional skin of patients with atopic dermatitis.

Ethanol is widely used in cosmetic formulations as a solvent, preservative, and penetration enhancer, yet its effects on atopic skin remain controversial. This study explores the impact of ethanol in skin care products on skin physiology, microbiome composition and subjective perception. A two-part investigation was conducted: (I) ex vivo analysis using porcine skin models exposed to varying ethanol concentrations, and (II) a double blinded, placebo controlled, randomized clinical pilot study on 9 patients with Atopic Dermatitis (AD) comparing creams with and without 12% ethanol. The ex vivo study revealed that ethanol concentrations above 15% negatively affected epidermal barrier integrity, increasing stratum corneum (SC) permeability and transepidermal water loss (TEWL). In the clinical trial, 12% ethanol demonstrated no significant adverse effects on SC hydration, erythema, pH, or TEWL over 30 days. Microbiome analysis revealed a localized increase in Xanthomonas species associated with ethanol use, while no significant community-wide changes were observed. The implications of increased Xanthomonas abundance in response to the application of a 12% ethanol cream for atopic dermatitis remain unclear. Subjective evaluations reported similar perceptions for both formulations, with no notable exacerbations in non-lesional AD skin. These findings indicate that ethanol in concentrations ≤ 12% is safe for atopic skin.