RESUMEN
BACKGROUND: There is a dearth of effective treatments to counter retinol-induced skin irritation. OBJECTIVE: This study aimed to investigate the efficacy of three potential mitigants: (i) phytosteryl/octyldodecyl lauroyl glutamate (PLG), (ii) a physiologic lipid mixture (PLM) comprised of ceramide three and cholesterol, and (iii) niacinamide, in ameliorating irritation instigated by retinol. METHODS: An occlusive human patch test, spanning 5 days, was undertaken on 18 Chinese participants aged between 23 and 40. It was designed as a randomized, double-blind, and vehicle-controlled study. Clinician erythema assessment (CEA) and instrumental evaluations were employed pre and post-test. Subsequently, a 4-week consumer in-use test, randomized and double-blind in nature, was executed to substantiate the soothing effects of PLG. RESULTS: Data from CEA and bioengineering assessments revealed that, in comparison to the vehicle control, both 2% PLG and 5% PLM notably curbed retinol-induced skin erythema and inflammation. Notably, PLG outperformed PLM. Conversely, 3% niacinamide did not offer relief against retinol-induced discomfort. The subsequent consumer in-use test affirmed that treatments with 2% PLG were better tolerated than those with the vehicle alone. CONCLUSION: To the best of our knowledge, this study represents the first confirmation that physiologic lipids effectively mitigate retinol-induced irritation. Given their capacity to counter retinol-induced irritation, physiologic lipids, particularly PLG, are recommended for incorporation in retinol regimens. Additionally, the Visia-CR a* value can serve as a robust objective measure for interpreting patch test outcomes.