Ascorbic Acid
A potent form of Vitamin C that brightens skin, boosts collagen, and provides antioxidant protection.
What is Ascorbic Acid?
CAS Number
50-81-7
Formula
C6H8O6
Molecular Weight
176.12 g/mol
Also known as: l-ascorbic acid, ascorbic acid, vitamin C, L(+)-Ascorbic acid, Ascoltin
What does Ascorbic Acid do for skin?
Ascorbic Acid functions as a potent antioxidant by neutralizing reactive oxygen species (ROS) generated by UV radiation and environmental pollutants, thereby preventing oxidative damage to skin cells and extracellular matrix components. It is an essential cofactor for prolyl and lysyl hydroxylases, enzymes critical for stabilizing and cross-linking collagen molecules, thus promoting collagen synthesis and improving skin elasticity. Furthermore, it inhibits tyrosinase, the key enzyme in melanogenesis, which reduces melanin production and mitigates hyperpigmentation.
Typical concentration: 5-20% (most active formulas use 10-15%; lower concentrations around 0.5-2% provide antioxidant benefits but less impact on collagen/pigmentation).
Is Ascorbic Acid safe?
The CIR Expert Panel has deemed Ascorbic Acid safe for use in cosmetics. While generally well-tolerated, high concentrations or low pH formulations may cause mild irritation or stinging, especially on sensitive skin. It is an FDA-approved ingredient for various over-the-counter drug products (e.g., oral supplements).
What does the research say about Ascorbic Acid?
Stability, transdermal penetration, and cutaneous effects of ascorbic acid and its derivatives
Pinnell KD, Journal of Cosmetic Dermatology, 2005, 4(1):8-16
Topical L-ascorbic acid: percutaneous absorption studies
Pinnell FR, Yang H, Levine M, Doublet M, Jones C, Journal of Dermatologic Surgery, 1999, 25(8):606-10
Ascorbic acid enhances the synthesis of new collagen by cultured human skin fibroblasts
Pinnell KD, Murad S, Darr D, Journal of Investigative Dermatology, 1989, 93(6):724-8
Regulatory Info
Can I mix Ascorbic Acid 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.