Introduction: Hyaluronic acid (HA) acts as a biologic humectant, thus retaining water in the skin, making HA useful as a topical moisturizing ingredient. The goal of the research was to evaluate the ability of a HA facial serum to deliver skin benefits.

Methods: Forty females 30-65 years of age with Fitzpatrick skin types I-VI who exhibited photoaging used the HA facial serum twice daily with sunscreen. The dermatologist investigator evaluated smoothness, plumping, hydration, fine lines/wrinkles, and global appearance issues on a 5-point ordinal scale. The subjects assessed product tolerability in terms of stinging, itching, and burning. Corneometry was undertaken, with assessments performed at baseline, immediately after application, and at weeks 2, 4, and 6. Facial swabbing and photography were performed at the same intervals on a subset of 15 subjects.

Results: The HA serum demonstrated excellent tolerability and produced an increase in skin hydration (as measured by corneometry) immediately after application of 134% (p < 0.001), with a sustained increase of 55% (p < 0.001) at week 6. At week 6, there was also improvement (p ≤ 0.001) in all evaluated attributes: smoothness (64%), plumping (60%), hydration (63%), fine lines (31%), wrinkles (14%), and overall global assessment (43%). Facial swabbing confirmed an increase in topical HA at week 6 (p = 0.04), accounting for the enhanced skin appearance, but there was no statistically significant increase in IL-1a, indicating no product irritation.

Conclusion: Topical HA in a serum formulation provides excellent skin hydration, as demonstrated through clinical, photographic, chemical, and instrumental assessments.