Sodium Ascorbyl Phosphate
소듐아스코빌포스페이트
A stable derivative of Vitamin C, acting as an antioxidant and skin brightener.
What is Sodium Ascorbyl Phosphate?
CAS Number
66170-10-3
Formula
C6H6Na3O9P
Molecular Weight
322.05 g/mol
Also known as: Sodium L-Ascorbyl-2-Phosphate, sodium ascorbyl phosphate, Sodium ascorbyl monophosphate, Trisodium ascorbate-2-phosphate, DTXSID601014965
What does Sodium Ascorbyl Phosphate do for skin?
Sodium Ascorbyl Phosphate (SAP) is a stable, water-soluble derivative of L-ascorbic acid (Vitamin C). Upon topical application, SAP is enzymatically converted into free L-ascorbic acid within the skin by endogenous phosphatases. Once converted, L-ascorbic acid functions as a potent antioxidant, neutralizing reactive oxygen species (ROS) to protect against UV-induced oxidative damage to skin cells and collagen. It also acts as a cofactor for lysyl and prolyl hydroxylases, enzymes essential for collagen synthesis, thus promoting skin firmness. Additionally, SAP inhibits tyrosinase activity, an enzyme crucial for melanin production, thereby reducing hyperpigmentation and brightening skin tone, and exhibits antimicrobial properties against *P. acnes*.
Typical concentration: 0.2-10% (most formulas utilize 1-5% for antioxidant and brightening effects; concentrations up to 3% are common for anti-acne benefits).
Is Sodium Ascorbyl Phosphate safe?
Sodium Ascorbyl Phosphate is generally considered safe and well-tolerated for topical use. As a stable pro-drug, it typically causes less irritation compared to pure L-ascorbic acid. The Cosmetic Ingredient Review (CIR) Expert Panel has assessed ascorbic acid and its salts, including SAP, as safe in cosmetics.
What does the research say about Sodium Ascorbyl Phosphate?
Ruamviboonsuk K, et al. J Cosmet Sci. 2004 Nov-Dec;55(6):533-40.
Al-Niaimi S, Chiang R. Clin Cosmet Investig Dermatol. 2017 Jan 26;10:1-7.
Anti-pigmentary effects of Sodium Ascorbyl Phosphate on cultured human melanocytes.
Kamata T, et al. J Dermatol Sci. 2007 May;46(2):147-50.
Regulatory Info
Can I mix Sodium Ascorbyl Phosphate 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.