18/06/2024 10:13 AM


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The Different Types of Vitamin C


Vitamin C is the loyal devotee you need in your routine, regardless of skin type or age. As one of the most potent antioxidants, vitamin C shields the skin against free radical damage — the one that leads to early aging signs. However, as good as it is, vitamin C has its downsides, and pronity to oxidation is one of them. Also, the active form of vitamin C is water-soluble, meaning its molecules are not small enough to penetrate the skin for intense results. For this reason, many more types of vitamin C keep popping up in skincare, with diverse solubility and stability levels.

While that’s a good thing, it makes picking the best form of vitamin C for your skin a difficult mission. In this post, we break down everything you need to know about the main types of vitamin C in skincare, so you will always choose the one that serves you best. Using a form of vitamin C that is not suitable for your skin type or a concentration that’s too high without building tolerance at first might lead to irritation. So read on.

Before we go to the good bit, you should know that all forms of vitamin C are converted in the body to L-ascorbic acid (the purest form of vitamin C), the form the body can use. This makes L-ascorbic acid the most potent form but also the most likely one to irritate. 

L-Ascorbic Acid  

  • Solubility: water-soluble
  • Strongest point: purity
  • pH: 3.4
  • Skin types: oily, mature, normal, combination
  • Best at a concentration of: 5% to 20% 

L-ascorbic acid is the most biologically active form of vitamin C, meaning it is the strongest as it doesn’t require to be converted to deliver benefits. For this reason, if you’re a vitamin C starter and planning to begin with the pure form of vitamin C, it is wise to start slowly to help your skin adjust to it. 

As a water-soluble compound, L-ascorbic acid has poor skin penetration, meaning it acts more on the top layer of the skin. The less pleasant thing about L-ascorbic acid is its pronity to degradation when exposed to light and air. Due to its vulnerability, L-ascorbic acid should be formulated without water or at a pH below 3.4 to increase its stability and permeability.[1] Remember that this might be too acidic for sensitized or dry skin. Another way to increase L-ascorbic acid’s stability is to use it along with other antioxidants, such as vitamin E and ferulic acid.

Good to know

  1. When L-ascorbic acid is used under sunscreen, it boosts photoprotection. 
  2. A concentration above 20% vitamin C does not increase its biological significance and, conversely, might cause some irritation.[1]
  3. Using a vitamin C serum with a concentration of 10% showed a significant reduction of UVB-induced damage by 52% and sunburn by 40-60%.[2]
  4. Use products with vitamin C in amber and air-tight glass bottles as it gets easily oxidized when in contact with air and light.


  1. SkinCeuticals C + E Ferulic
  2. Allies of Skin Perfecting Serum
  3. Some By Mi Vitamin C Glow Toner

Sodium Ascorbyl Phosphate

  • Solubility: water-soluble
  • pH: 7
  • Skin types: acne-prone, oily, combination
  • Strongest point: antimicrobial
  • Best at a concentration of: 5% to 10% 
  • What else: more stable than magnesium ascorbyl phosphate

Sodium Ascorbyl Phosphate (SAP) is a water-soluble form of vitamin C with a salt molecule attached, making it easier to sink into the skin. Unlike L-ascorbic acid, SAP has excellent stability up to pH 7 and is gentler than L-ascorbic acid. Usually, sodium ascorbyl phosphate fulfills its antioxidant, collagen-inducing, and brightening benefits when used in concentrations ranging from 0.0% to 3%.[3]

Furthermore, a review by the International Journal of Cosmetic Science found that 1% SAP has major antimicrobial effects on acne-causing bacteria, making it a go-to for acne sufferers. Also, 5% sodium ascorbyl phosphate proved to be more effective than benzoyl peroxide and salicylic acid in treating and preventing acne without side effects.[4]

Magnesium Ascorbyl Phosphate

  • Solubility: water-soluble
  • pH: 7
  • Skin types: acne-prone, sensitive, dry
  • Best at a concentration of: 5% to 10% 
  • Strongest point: hydrating
  • What else: more stable than magnesium ascorbyl phosphate

Magnesium ascorbyl phosphate (MAP) is a stable form of vitamin C in skincare, which works great when formulated at neutral pH. For this reason, magnesium ascorbyl phosphate is suitable for dry and sensitive skin, as it’s less irritating. Unlike L-ascorbic acid, MAP doesn’t degrade in formulas containing water, and it’s actually added to products to stabilize them.[6]

Magnesium ascorbyl phosphate is a potent free radical scavenger, skin hydrator, and brightener. Moreover, it’s been found that MAP works amazingly for inflamed pimples.[7] Magnesium ascorbyl phosphate is considered a stable and effective antioxidant for the skin and usually comes in concentrations around 5%. Its neutral pH makes it easy to formulate with and reduces the chances of sensitivities.

Ascorbyl Palmitate

  • Solubility: oil-soluble
  • pH: up to 6
  • Skin types: sensitive, dry, mature
  • Strongest point: reducing UV damage 
  • Best at a concentration of: 0.1 to 1%
  • What else: Greater stability when encapsulated[9]

Ascorbyl palmitate is an oil-soluble form of vitamin C, to which is added a fatty acid (palmitic acid) to make it more stable and gentler. Since ascorbyl palmitate is combined with a fatty acid, its hydrating benefits are higher than other types of vitamin C in skincare. 

However, even if it’s soluble in oil and penetrates the skin more in-depth than L-ascorbic acid, its conversion into the pure form of vitamin C may be limited.[10] As a fat-soluble compound, ascorbyl palmitate is often used in oil-based cosmetics, so if you’re prone to breakouts, ensure the product is non-comedogenic. 

3-O-ethyl-ascorbic acid

  • Solubility: oil- and water-soluble
  • pH: between 4 and 6
  • Skin types: sensitive, dry, mature
  • Best at a concentration of: 0.1 to 1%
  • Strongest point: brightening
  • What else: better than ascorbyl glucoside at getting into the skin

3-O-ethyl-ascorbic acid is a stable derivative of L-ascorbic acid. Due to its solubility in both water and oil, 3-O-ethyl-ascorbic acid has excellent penetration, meaning it can trigger changes in the deeper layer of the skin. This form of vitamin C carries antioxidant, anti-inflammatory, and collagen-boosting benefits, and it’s especially good at brightening the skin as it’s a potent tyrosinase inhibitor.[11]

Ascorbyl Glucoside

  • Solubility: water-soluble
  • pH: between 4 and 6
  • Skin types: oily, acne-prone, dry, normal, combination
  • Best at a concentration of: 0.1 to 1%
  • Strongest point: it’s gentle

Ascorbyl glucoside is a form of vitamin C combined with glucose (sugar) that carries all the benefits vitamin C has while being gentler. Since it requires to be converted into the pure form of vitamin C, ascorbyl glucoside is milder, hence more suitable for easily reactive skin. 

Tetrahexyldecyl Ascorbate 

  • Solubility: oil-soluble
  • pH: lower than 6.5
  • Skin types: oily, acne-prone, dry, normal, combination
  • Best at a concentration of: 0.1 to 1%
  • Strongest point: great skin penetration

Tetrahexyldecyl ascorbate (THD) is a widely used type of vitamin C in skincare due to its ability to penetrate the epidermis. Its benefits are similar to the purest form of vitamin C; it shields against oxidative stress, enhances collagen production, brightens, heals, and increases hydration. For anti-aging benefits, THD should be paired with retinol, vitamin E, and CoQ10.[10]

What’s the best form of vitamin C

L-ascorbic acid is the best type of vitamin C in terms of potency, while magnesium ascorbyl phosphate is the most stable form used in skincare. Also, ascorbyl glucoside and ascorbyl palmitate are the best forms of vitamin C for people with sensitive skin

Frequently asked questions

  1. Can vitamin C be absorbed through the skin?

    Vitamin C crosses the epidermis into the dermal layers, where it triggers changes in skin brightening and collagen production and provides an antioxidant shield.

  2. Is oxidized vitamin C bad for skin?

    Oxidized vitamin C is not bad for skin and is unlikely to cause damage, but not good either, as it’s degraded and ineffective.


Women’s Concepts uses reliable sources, including dermatologists’ insights, clinical trials, and scientific journals, to find accurate information and support all the facts shared in our articles. All statements and claims have clear and legit references. Read our editorial policy to learn more about our sources of information, our process of researching and fact-checking the content, and how our team strives to keep all articles updated, completed, and trustworthy.

  1. Al-Niaimi F, Chiang NYZ. Topical Vitamin C and the Skin: Mechanisms of Action and Clinical Applications. J Clin Aesthet Dermatol. 2017 Jul;10(7):14-17. Epub 2017 Jul 1. PMID: 29104718; PMCID: PMC5605218.
  2. Telang PS. Vitamin C in dermatology. Indian Dermatol Online J. 2013 Apr;4(2):143-6. doi: 10.4103/2229-5178.110593. PMID: 23741676; PMCID: PMC3673383.
  3. International Journal of Toxicology, 24(Suppl. 2):51–111, 2005, Final Report of the Safety Assessment of L-Ascorbic Acid, Calcium Ascorbate, Magnesium Ascorbate, Magnesium Ascorbyl Phosphate, Sodium Ascorbate, and Sodium Ascorbyl Phosphate as Used in Cosmetics
  4. Klock J, Ikeno H, Ohmori K, Nishikawa T, Vollhardt J, Schehlmann V. Sodium ascorbyl phosphate shows in vitro and in vivo efficacy in the prevention and treatment of acne vulgaris. Int J Cosmet Sci. 2005 Jun;27(3):171-6. doi: 10.1111/j.1467-2494.2005.00263.x. PMID: 18492184.
  5. Hira Khan, Naheed Akhtar, Atif Ali, Fortification of facial skin collagen efficacy by combined ascorbyl palmitate and sodium ascorbyl phosphate, January 2018, 
  6. Slim Smaoui, Hajer Ben Halima, and Adel Kadri, Application of l-Ascorbic Acid and its Derivatives (Sodium Ascorbyl Phosphate and Magnesium Ascorbyl Phosphate) in Topical Cosmetic Formulations: Stability Studies, Department of Life Sciences, Sciences Faculty of Sfax, BP 1171, Sfax 3000, Tunisia
  7. Lee WJ, Kim SL, Choe YS, Jang YH, Lee SJ, Kim DW. Magnesium Ascorbyl Phosphate Regulates the Expression of Inflammatory Biomarkers in Cultured Sebocytes. Ann Dermatol. 2015 Aug;27(4):376-82. doi: 10.5021/ad.2015.27.4.376. Epub 2015 Jul 29. PMID: 26273151; PMCID: PMC4530145.
  8. Andy Manggabarani, Farida Tabri, Anis Irawan, Arifin Seweng, Agussalim Bukhari, Khairuddin Djawad, A randomized study, Effectivness of glutathione (gsh) 2%, tocopheryl acetate 1%, and magnesium ascorbyl phosphate 3% combination cream compared with hydroquinone 4% cream as a skin lightening agent
  9. Teeranachaideekul V, Müller RH, Junyaprasert VB. Encapsulation of ascorbyl palmitate in nanostructured lipid carriers (NLC)–effects of formulation parameters on physicochemical stability. Int J Pharm. 2007 Aug 1;340(1-2):198-206. doi: 10.1016/j.ijpharm.2007.03.022. Epub 2007 Mar 24. PMID: 17482778.
  10. Safety Assessment of Ethers and Esters of Ascorbic Acid as Used in Cosmetics
  11. Liao WC, Huang YT, Lu LP, Huang WY. Antioxidant Ability and Stability Studies of 3-O-Ethyl Ascorbic Acid, a Cosmetic Tyrosinase Inhibitor. J Cosmet Sci. 2018 Jul/Aug;69(4):233-243. PMID: 30311899.


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