Split-face study of topical 23.8% L-ascorbic acid serum in treating photo-aged skin.

Background: L ascorbic acid has been widely used to treat photo-aged skin. However, its aqueous formula is prone to oxidation. Therefore, a new formula that contains 23.8% L-ascorbic acid and a chemical penetration enhancer was developed. Objective: Observe the efficacy and safety of topical 23.8% L-ascorbic acid serum on photo-aged skin. Methods: Twenty Chinese women with photo-aged skin were enrolled in this split-face study. They were treated with topical L-ascorbic acid serum with iontophoresis on one side of the face once a day for 2 weeks; the other side of the face was spared treatment through participants' self-control. Changes in photo-aged skin were evaluated using a global evaluation, an overall self-assessment, a spectrophotometer, the phase-shift rapid in vivo measurement of skin (PRIMOS) 3D, and a corneometer. Results: Sixteen of 20 patients (80%) experienced a score decrease of 2 or 3 grades, according to the dermatologist. Fifteen patients (75%) rated their overall satisfaction as excellent or good. Dyspigmentation, surface roughness, and fine lines on the treated side improved significantly. Conclusion: Topical 23.8% L-ascorbic acid serum is effective for the treatment of photo-aged skin and does not cause any obvious side effects.