Lactic Acid



Lactic Acid at a glance

  • Can be extracted from milk or synthetically made
  • Exfoliates the surface of skin
  • Has hydrating properties and strengthens skin’s barrier
  • Helps positively influence skin’s microbiome

Lactic Acid description

Lactic acid is an alpha hydroxy acid (AHA) extracted from milk. Despite such natural origins, most forms used in cosmetics are synthetic because that form is easier to stabilise and formulate with, plus it’s vegan.In a pH-correct formula (ideally a pH between 3 and 4) and in concentrations between 5 and 12%, lactic acid exfoliates on the surface of skin. It does this by breaking down the material that holds dead skin together, allowing it to shed naturally as it once did. Lactic acid also has hydrating properties (as sodium lactate, it is part of skin’s natural moisturising factor, or NMF).In addition to these benefits, lactic acid strengthens skin’s barrier by encouraging it to make more ceramides, a key component of healthy skin. It also strongly influences skin’s microbiome, helping to keep its first line of defence strong by positively interacting with a neuropeptide in skin’s surface known as Substance P, resulting in quick diffusion of signs skin is stressed.Like glycolic acid (another popular AHA), it helps brighten an uneven, dull skin tone.

Lactic Acid references

  • International Journal of Cosmetic Science, April 2020, pages 116-126
  • International Journal of Dermatology, March 2019, ePublication
  • Clinical, Cosmetic, and Investigational Dermatology, October 2018, pages 491-497
  • International Journal of Dermatology, September 2018, ePublication
  • Molecules, April 2018, ePublication
  • Journal of the American Dental Association, April 2016, pages 255-263
  • Cutis, January 2016, pages E9-E11
  • Clinical, Cosmetic, and Investigational Dermatology, November 2010, pages 135-142
  • The Journal of Dermatology, January 2006, pages 16-22

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