Vitamin C (Topical, L-Ascorbic Acid)

What it is

L-ascorbic acid is the most bioactive topical form of vitamin C and a potent antioxidant that neutralizes free radicals generated by UV exposure. It also serves as a cofactor for the enzymes that stabilize and crosslink collagen, supporting firmness, and inhibits melanin formation to even tone. To penetrate skin it must be formulated at a low pH, generally below 3.5.

Benefits

Topical vitamin C improves photoaged skin, reduces UV-induced pigmentation, and supports collagen and antioxidant defense, with benefits enhanced when stabilized by ferulic acid or vitamin E. Concentrations of roughly 10-20% are considered optimal, as biological effect plateaus and irritation rises above 20%.

When to take it

Apply in the morning under sunscreen, where its antioxidant activity complements UV protection. Store in opaque, air-tight packaging and replace if it darkens.

Side effects

The low pH needed for absorption can cause stinging, redness, or dryness, especially on sensitive skin. Oxidized (yellow-brown) product loses potency and may be more irritating.

Sources

• Topical Vitamin C and the Skin: Mechanisms of Action and Clinical Applications
• Topical ascorbic acid on photoaged skin: a double-blind study vs. placebo

Products containing Vitamin C (Topical, L-Ascorbic Acid)

No products in our database contain this ingredient yet.