As cited above in the presentation of “Mechanisms of Action,” the effcacy of topical vitamin C in neutralizing reactive oxygen species (ROS), protecting against both UVA and UVB damage, stimulating collagen synthesis, preventing UV immunosuppression, alleviating infammation, decreasing UV-induced pigmentation, and enhancing surface moisturization and skin barrier function has been repeatedly documented in controlled experiments.
Clinically, daily application of topical vitamin C 15% can partially reverse the appearance of photoaged skin. Improvement can be noted in as little as two to four months with optimal correction after at least four to six months. As shown in Figures 1 and 2, small wrinkles decrease and solar lentigines fade. Thus vitamin C not only prevents but also reverses much of the damage induced by UV.