vitamin c
Antioxidant that brightens skin, boosts collagen production, and protects against environmental damage.
What is vitamin c?
CAS Number
50-81-7
Formula
C6H8O6
Molecular Weight
176.12 g/mol
Also known as: Ascorbic Acid, L-Ascorbic Acid, LAA
What does vitamin c do for skin?
Potent antioxidant that donates electrons to neutralize free radicals generated by UV exposure. Essential cofactor for prolyl hydroxylase and lysyl hydroxylase enzymes in collagen biosynthesis. Inhibits tyrosinase activity, reducing melanin production. At pH <3.5 and 10-20% concentration, penetrates the stratum corneum effectively. Synergistic with vitamin E (regenerates tocopheroxyl radicals).
Typical concentration: 5-20% (L-ascorbic acid); derivatives vary
Is vitamin c safe?
Generally well tolerated. May cause mild stinging at low pH. Highly unstable (oxidizes on contact with air and light). CIR Expert Panel: safe as used in cosmetics up to 20%.
What does the research say about vitamin c?
Topical vitamin C and the skin: mechanisms of action and clinical applications
Telang, Indian Dermatology Online Journal, 2013
Stability and bioavailability of L-ascorbic acid in topical formulations
Pinnell et al., Dermatologic Surgery, 2001
Can I mix vitamin c with other ingredients?
Benzoyl peroxide oxidizes vitamin C and makes it completely ineffective. Use vitamin C in the morning and benzoyl peroxide at night.
Peptides
Vitamin C's low pH may reduce peptide effectiveness. Copper peptides in particular may bind with vitamin C and reduce its potency. Consider waiting a few minutes between them or using in separate routines.
Vitamin C with AHAs can be too acidic for some skin types. If you experience stinging, use them in separate routines.
Vitamin C and BHA together may be too acidic. If your skin tolerates it, it's fine. Otherwise, separate into AM/PM.
Retinoids and vitamin C have different pH needs. Together they may irritate and reduce effectiveness. Best to use vitamin C in AM, retinoid in PM.
Growth Factors
Vitamin C's low pH may reduce growth factor effectiveness when layered together. Consider using in separate routines for best results.
Niacinamide and vitamin C are generally safe to layer — older concerns about flushing are largely debunked at normal usage concentrations. If your skin is very sensitive, wait a few minutes between application.
Benzoyl peroxide oxidizes vitamin C. If both are in your routine, use vitamin C in AM and benzoyl peroxide in PM.
Zinc can interfere with vitamin C absorption when layered directly. Apply vitamin C first and let it absorb before zinc-based products.
Hydroquinone
Both target hyperpigmentation through different paths. Together they can irritate. Alternate AM/PM for best results.
Denatured Alcohol
Alcohol can destabilize vitamin C and increase skin dryness. Apply vitamin C before any alcohol-containing product.
General guidance
Vitamin C is most effective in the morning. It boosts your SPF's UV protection with antioxidant defense.
General guidance
Vitamin C + Vitamin E + SPF is the gold standard morning trio. Vitamin E stabilizes C and together they boost UV protection.
Vitamin C and Vitamin E are a synergistic antioxidant duo. Vitamin E stabilizes vitamin C, extending its potency and boosting UV protection together.
Unlike retinol, bakuchiol is stable at low pH and safe to combine with vitamin C. A gentler anti-aging + brightening combo.
Tranexamic acid + vitamin C target hyperpigmentation from multiple angles. Safe to layer together for faster brightening.
Arbutin + vitamin C target hyperpigmentation from multiple angles without the pH conflicts of hydroquinone. A gentler brightening combo.
Kojic Acid
Kojic acid and vitamin C both target hyperpigmentation through different mechanisms and are safe to layer together for a stronger brightening effect.
Read all ingredient interaction guides for layering order and science-backed advice.