L-Ascorbic Acid (Vitamin C)
INCI: Ascorbic Acid
Water-soluble antioxidant that inhibits tyrosinase and stimulates collagen synthesis. Unstable upon oxidation, requiring careful storage.
Evidence by route
Topical application
BLimited evidence. One RCT or several controlled studies with limitations.
Clinical trials confirm efficacy for melasma, photoaging, and photoprotection. Synergy with vitamin E and ferulic acid enhances photoprotective properties. Evidence base is limited by difficulties in standardizing formulation stability.
- Pullar JM et al. Nutrients. 2017;9(8):866.
- Murray JC et al. J Am Acad Dermatol. 2008;58(3):418-424.
Working concentrations
10–20% (optimal pH 2.5–3.5)
Tolerability and safety
Irritation potential
MediumAllergen risk
LowPregnancy
SafeFor sensitive skin
Concentrations above 15% may cause stinging and redness on sensitive skin. Starting at 10% is recommended.
Skin types
Suitable for
Use with caution
Combinations with other ingredients
Works well with
Tocopherol (Vitamin E)Токоферол (витамин E)
Classic pair: vitamin E stabilizes ascorbic acid and enhances photoprotection. Lin 2003 showed 4-fold UVB protection boost when combined.
Ferulic AcidФеруловая кислота
Ferulic acid stabilizes vitamin C and doubles the formula's photoprotective properties. They work as a single antioxidant network.
Glycolic AcidГликолевая кислота
Applying vitamin C over AHA boosts bioavailability of both – low pH helps ascorbic acid stability. Best done in the morning.
NiacinamideНиацинамид
The old incompatibility myth is debunked. In modern formulas these ingredients work together, enhancing brightening and antioxidant effects.
Does not combine with
Copper Peptides (GHK-Cu)Медные пептиды (GHK-Cu)
Vitamin C reduces copper in GHK-Cu, breaking the peptide. Use at different times: C in morning, copper peptides in evening.
Benzoyl PeroxideБензоилпероксид
BPO oxidizes ascorbic acid, inactivating it. Use at different times of day.
RetinolРетинол
Different optimal pH: retinoids need neutral, vitamin C needs acidic. Use at different times: C in morning, retinol at night.
Frequently asked questions
Is L-Ascorbic Acid (Vitamin C) safe during pregnancy?
L-Ascorbic Acid (Vitamin C) is considered safe during pregnancy at typical cosmetic concentrations. Systemic absorption through the skin is minimal.
What skin types is L-Ascorbic Acid (Vitamin C) for?
L-Ascorbic Acid (Vitamin C) suits: normal, combination, oily. Use with caution in: sensitive, dry.
Can L-Ascorbic Acid (Vitamin C) irritate the skin?
L-Ascorbic Acid (Vitamin C) has moderate irritation potential. Sensitive skin may show a transient reaction that usually settles with adaptation.