3-O-Cetyl Ascorbic Acid

3-O-cetyl ascorbic acid is a lipid-soluble derivative of vitamin C (ascorbic acid). By attaching a cetyl chain to the vitamin C molecule, manufacturers create a form that is more chemically stable than pure ascorbic acid and better able to penetrate the skin's outermost layers.

Once absorbed, the skin's natural enzymes convert this derivative into active ascorbic acid, where it can function as an antioxidant and support collagen synthesis. The derivative form allows for easier formulation and longer shelf stability compared to unmodified vitamin C.

3-O-cetyl ascorbic acid works through two mechanisms. First, its lipid-soluble structure allows it to penetrate the skin more readily than water-soluble vitamin C forms. Second, once inside the skin, enzymes cleave the cetyl chain, releasing free ascorbic acid.

Active ascorbic acid then functions as a cofactor for enzymes involved in collagen cross-linking and acts as a free radical scavenger. This dual action supports skin's structural integrity and defence against oxidative damage.

3-O-cetyl ascorbic acid products are generally well-tolerated and can be used daily as part of a morning or evening routine. Apply to clean, dry skin before moisturiser. Pair with sunscreen during the day, as vitamin C derivatives offer some photoprotection but do not replace dedicated sun protection. Store products in a cool, dark place to maintain stability, and check the product's shelf-life guidance.