The evidence favours retinol: multiple studies document concrete wrinkle reduction and collagen stimulation, whereas vitamin C carries the same recommendation grade but its effect size is less thoroughly elaborated. A direct comparison between the two agents does not yet exist. In practical terms, retinol is the better-supported starting point, with the caveat that it can cause irritation and that prescription tretinoin is the most strongly proven alternative for those who want more.
Both agents, retinol and vitamin C, receive a Grade A recommendation for anti-aging in a large systematic review (32 studies, 1236 patients, of which 20 were randomised controlled trials). That is the highest possible recommendation grade. Nevertheless, the evidence for retinol is considerably more extensive: multiple studies show significant wrinkle reduction after 12 weeks of use and stimulation of collagen production. A Grade A recommendation also exists for vitamin C, but the studies in the review describe the effect size far less concretely, and the direct comparative research in the sources focuses almost exclusively on retinol.
Retinol works through the same biological mechanism as tretinoin, the most potent retinoid available only on prescription. Over-the-counter retinol produces comparable but smaller changes in skin structure and collagen gene expression than tretinoin. Those seeking the strongest proven effect will therefore benefit most from prescription tretinoin; retinol is a weaker but more accessible variant of the same principle.
A significant drawback of retinol is skin irritation: users report significantly more frequent flaking and a stinging sensation than with some alternatives. This is a well-known effect that can get in the way of adherence, especially at higher concentrations or with daily use. Starting with a low concentration and gradually increasing it reduces this risk.
A direct head-to-head comparison between retinol and vitamin C in a randomised trial is absent from the available sources. Based on what is known, retinol has the broader and more concrete evidence base for wrinkle reduction. Vitamin C is a proven antioxidant for the skin with the same recommendation grade, but the evidence for its specific effect on wrinkles is more thinly documented in the literature examined.
Based on one systematic review (PMID 38758222, 32 studies, 1236 patients, 20 RCTs), two additional retinol studies (PMID 26578346, 40707570), a 12-week RCT on irritation (PMID 29947134), and two studies on the mechanism versus tretinoin (PMID 36220974, 39348007). No direct RCT of retinol vs. vitamin C is available in the sources.