Alpha Hydroxy Acid



Alpha Hydroxy Acid description

Alpha hydroxy acid is also known by its acronym, AHA. AHAs are derived naturally from various plant sources and from milk, but 99% of the AHAs used in cosmetics are synthetically derived. In low concentrations (less than 3%), AHAs work as water-binding agents. At concentrations greater than 4% and in a base with an acid pH of 3 to 4, these ingredients can exfoliate by breaking down the substance that holds dead skin together.The most effective and well-researched AHAs are glycolic acid and lactic acid. Malic acid, citric acid, and tartaric acid may also be effective.AHAs may sensitise mucous membranes. However, AHAs have been widely used for improving signs of ageing, dry skin and an uneven skin tone, all of which lead to younger-looking skin.There is a vast amount of research that substantially describes how the ageing process affects skin and that demonstrates that many of the unwanted changes can be improved by topical application of AHAs, including glycolic and lactic acids. AHA use can result in increased sensitivity to the sun, though wearing a sunscreen daily eliminates this risk.*Note:* AHAs are of little benefit when added to rinse-off products, as their contact with skin is too brief for them to function as exfoliants or absorb into skin.

Alpha Hydroxy Acid references

  • Jundishapur Journal of Natural Pharmaceutical Products, January 2012, pages 9-10
  • Evidence Based Complementary and Alternative Medicine, June 2011, ePublication

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