Magnesium Ascorbyl Phosphate



Magnesium Ascorbyl Phosphate at a glance

  • Water-soluble yet oil-loving stabilised form of vitamin C
  • Delivers many of the same benefits as vitamin C
  • Promotes hydration deeper in skin, but not as potent an antioxidant as pure vitamin C
  • Isn’t beholden to a low pH for efficacy and is generally well tolerated
  • Soothing properties may play a role in reducing blemishes

Magnesium Ascorbyl Phosphate description

Magnesium ascorbyl phosphate (MAP, for short) is a water-soluble form of vitamin C made by combining ascorbic acid (pure vitamin C) with a magnesium salt to improve its stability in water-based formulas. It is considered stable in the presence of light and air but is not impervious to diminished efficacy when exposure to both elements is persistent. Unlike other water-soluble forms of vitamin C, magnesium ascorbyl phosphate is also lipophilic, or oil-loving, which improves penetration into skin (although how well this form converts to ascorbic acid within skin is up for debate). Because of its oil-loving nature and its ability to promote hydration deeper in skin when compared to ascorbic acid (which instead showed greater antioxidant ability), MAP is considered one of the most hydrating forms of vitamin C. Like most forms of vitamin C, magnesium ascorbyl phosphate has been shown to improve the look of an uneven skin tone when used in concentrations between 2-5%. Concentrations between 5-10% are known to have more pronounced benefits for discolourations, including post-breakout marks, as well as improving skin’s firm look and feel. Amounts below 2% all the way down to 0.1% still deliver antioxidant benefits. Magnesium ascorbyl phosphate does not require the same low pH ascorbic acid does in order to be effective. It works best at pH levels between 5-6. Going above pH 6 can cause this ingredient to discolor. This form of vitamin C may play a special role in reducing the likelihood of blemishes since its soothing action helps quell an of oil-based saccharide that can irritate skin. However, research on this matter was not comparative, meaning we don’t know how a range of other forms of vitamin C would’ve fared. It is considered safe as used in cosmetics.

Magnesium Ascorbyl Phosphate references

  • International Journal of Biological Macromolecules, January 2021, pages 333-341
  • The Journal of Clinical and Aesthetic Dermatology, July 2017, pages 14-17; and July 2010, pages 20-31
  • Annals of Dermatology, February 2016, pages 129-132; and August 2015, pages 376-382
  • International Journal of Dermatology, January 2014, pages 93-99
  • Indian Dermatology Online Journal, April-June 2013, pages 143-146
  • Skin Research and Technology, August 2008, pages 376-380
  • International Journal of Toxicology, Supplement 24, 2005, pages 51-111

Peer-reviewed, substantiated scientific research is used to assess ingredients in this dictionary. Regulations regarding constraints, permitted concentration levels and availability vary by country and region.

Ingredient ratings


Proven and supported by independent studies. Outstanding active ingredient for most skin types or concerns.


Necessary to improve a formula's texture, stability, or penetration.


Generally non-irritating but may have aesthetic, stability, or other issues that limit its usefulness.


There is a likelihood of irritation. Risk increases when combined with other problematic ingredients.


May cause irritation, inflammation, dryness, etc. May offer benefit in some capability but overall, proven to do more harm than good.


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Not rated