Behind the term "vitamin C" there are actually several active ingredients. In fact, vitamin C exists in different forms that are not all created equal, especially in terms of efficacy, tolerability, and stability. What are the derivatives of vitamin C? How can you recognize them on INCI lists? Continue reading to find out.
What are the different forms of vitamin C?
Published on May 13, 2022, updated on December 3, 2025, by Maylis, Chemical Engineer — 6 min of reading
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A closer look at pure vitamin C and its derivatives in cosmetics.
The vitamin C pure, in other words L-ascorbic acid (INCI name: Ascorbic Acid), appears as yellowish crystals or powder. This form of vitamin C is the most well-known of all and delivers excellent results, particularly on the signs of photoaging and skin radiance. However, ascorbic acid has an acidic pH, around 3.5, a parameter that must be considered when formulating a pure vitamin C treatment to prevent oxidation issues. Yet this acidic pH can irritate the skin, whose physiological pH is around 5.5–6. This is why, in practice, ascorbic acid is infrequently incorporated into cosmetic formulas, and derivatives of vitamin C are often used instead. They also provide similar benefits.
Chemical structure of ascorbic acid.
Source: PubChem.
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Vitamin C derivatives are generally combinations of ascorbate (vitamin C in a non-acidic form) with alkalinizing minerals (calcium, magnesium, sodium...).
Sodium ascorbyl phosphate (INCI name: "Sodium Ascorbyl Phosphate").
The sodium ascorbyl phosphate is a water-soluble derivative of vitamin C designed to circumvent the natural instability of ascorbic acid. Thanks to its phosphorylated structure, it is more resistant to oxidation, light, and heat, and is regarded as a more reliable active ingredient in aqueous formulations. Once applied to the skin, it can be converted into active ascorbic acid through the action of specific skin enzymes, notably phosphatases, ensuring a gradual and controlled release of vitamin C. It also contributes to improved tolerability: unlike pure vitamin C, this derivative is less irritating, making it particularly suitable for sensitive skin.
Chemical structure of "Sodium Ascorbyl Phosphate".
Source: PubChem.
Magnesium ascorbyl phosphate (INCI name: "Magnesium Ascorbyl Phosphate").
Magnesium ascorbyl phosphate is another highly stable, water-soluble derivative of vitamin C. Like sodium ascorbyl phosphate, it gradually converts into ascorbic acid once applied to the skin by cutaneous enzymes, becoming active and ensuring a controlled, long-lasting release of vitamin C. Magnesium ascorbyl phosphate is also suitable for sensitive skin and can, like ascorbic acid, stimulate collagen synthesis, improve skin tone uniformity, and diminish signs of aging.
Chemical structure of "Magnesium Ascorbyl Phosphate".
Source: PubChem.
Ascorbyl Tetraisopalmitate (INCI name: "Ascorbyl Tetra Isopalmitate").
The ascorbyl tetraisopalmitate is a oil-soluble derivative of vitamin C, meaning that, unlike ascorbic acid and the forms presented below, it is oil-soluble. It therefore has an excellent affinity for the epidermis and penetrates relatively easily into the stratum corneum, the outermost layer of the skin which is composed primarily of lipids. Ascorbyl tetraisopalmitate is often found in oils or oil-based serums.
Chemical structure of "Ascorbyl Tetra Isopalmitate".
Source: PubChem.
Ascorbyl palmitate (INCI name: "Ascorbyl Palmitate").
The ascorbyl palmitate is a lipophilic derivative of vitamin C, obtained by combining ascorbic acid with palmitic acid. This lipophilicity allows it to better integrate into oil-based formulations and to penetrate the epidermal lipid barrier more easily. Like other vitamin C derivatives, once absorbed it converts into active ascorbic acid and contributes to protecting the skin from oxidative stress.
Chemical structure of "Ascorbyl Palmitate".
Source: PubChem.
Ascorbyl glucoside (INCI name: "Ascorbyl Glucoside").
Ascorbyl glucoside is a water-soluble derivative of vitamin C in which ascorbic acid is bound to a sugar (glucose), significantly enhancing its stability against oxidation. Once applied to the skin, enzymes in the epidermis hydrolyze this compound to progressively release active ascorbic acid, thus ensuring prolonged efficacy.
Chemical structure of "Ascorbyl Glucoside".
Source: PubChem.
3-O-ethyl ascorbate (INCI name: "3-O Ethyl Ascorbate").
3-O-ethyl ascorbate is a lipid-soluble and particularly stable derivative of vitamin C, designed to resist oxidation and degradation in cosmetic formulations. It is distinguished by its high tolerability and its ability to penetrate the skin rapidly, allowing it to act in a short time.
Chemical structure of "3-O Ethyl Ascorbate".
Source: PubChem.
At Typology, we primarily use derivatives in our vitamin C skincare treatments, notably “Sodium Ascorbyl Phosphate,” “Ascorbyl Tetraisopalmitate,” “3-O-Ethyl Ascorbic Acid,” and “Ascorbyl Glucoside.”
Sources
TELANG P. S. Vitamin C in dermatology. Indian Dermatology Online Journal (2013).
LEONARDI G. R. & al. Cosmetics formulations containing vitamin C and the instability challenge. Research Journal of Topical and Cosmetic Sciences (2022).
GOLD M. H. & al. Vitamin C: Its role in cosmeceuticals. Dermatological Reviews (2024).
ROBLES VELASCO M. V. & al. New discoveries of the action of L-ascorbic acid (vitamin C) – Enhanced efficacy in formulations. Brazilian Journal of Pharmaceutical Sciences (2025).
