Antioxidant
Vitamin C (L-Ascorbic Acid)
L-ascorbic acid is the most studied form of topical vitamin C. It may support collagen synthesis, brighten skin tone, and provide additional photoprotection when used under sunscreen.
topicalantioxidantbrightening
Last reviewed: March 2026 · Our methodology
What It Does
Topical vitamin C (particularly L-ascorbic acid at 10-20%, pH below 3.5) acts as an antioxidant, neutralising free radicals from UV exposure and pollution. It may support collagen production and inhibit melanin synthesis, leading to a brighter, more even skin tone over time.
Best Use Cases
- Brightening and evening skin tone
- Antioxidant photoprotection (alongside sunscreen)
- Supporting collagen synthesis
- Mild pigmentation improvement
Who May Benefit Most
Most adults looking for antioxidant protection and brightening. Particularly useful for those exposed to sun and pollution regularly.
Cautions
L-ascorbic acid serums can sting or cause irritation, especially on sensitive or compromised skin. The low pH required for efficacy is not tolerated by everyone. Consider derivatives (ascorbyl glucoside, ethylated ascorbic acid) for sensitive skin.
Common Mistakes
- Storing vitamin C serum in warm, bright places (it oxidises quickly)
- Using an oxidised (dark brown) serum — replace it
- Expecting vitamin C alone to fix deep pigmentation
- Applying too many low-pH actives in the same routine step
Combines Well With
- Sunscreen (vitamin C boosts photoprotection)
- Vitamin E and ferulic acid (stabilisation and synergy)
- Niacinamide (fine in most modern formulations)
May Combine Poorly With
- Other low-pH actives at the same time (AHA, BHA) — can increase irritation
- Benzoyl peroxide (may oxidise vitamin C on contact)
Realistic Timeline
Brightening effects may be noticeable within 4-8 weeks. Full antioxidant and collagen benefits develop over 3-6+ months of consistent AM use.
Disclaimer
Vitamin C is not a sunscreen replacement. Always use broad-spectrum SPF alongside vitamin C for photoprotection.