lactic acid

Alpha hydroxy acid (AHA) extracted from milk, although most forms used in cosmetics are synthetic because that form is easier to formulate with and stabilise.

In a pH-correct formula (generally a product would have a pH between 3 and 4) and in concentrations between 5 and 12%, lactic acid exfoliates on the surface of skin by breaking down the material that holds dead skin together, allowing it to shed naturally as it once did. Lactic acid may cause sensitivity, although this isn’t common and can be minimised, if not eliminated, if the formulation contains soothing ingredients.

Lactic acid also has hydrating properties and, like glycolic acid (another AHA), helps brighten an uneven skin tone.

Reference for this information:

Journal der Deutschen Dermatologischen Gesellschaft, 2012, issue 7, pages 488-491

Clinical, Cosmetic, and Investigational Dermatology, November 2010, pages 135-142

Journal of the American Academy of Dermatology, September 1996 pages 388-391

Archives of Dermatology, June 1996, pages 631-636


Back to Ingredient Dictionary

About the Experts

Paula Begoun is the best-selling author of 20 books about skincare and makeup. She is known worldwide as The Cosmetics Cop and creator of Paula’s Choice Skincare. Paula’s expertise has led to hundreds of appearances on national and international radio, print, and television including:

The Paula's Choice Research Team is dedicated to busting beauty myths and providing expert advice that solves your skincare frustrations so you can have the best skin of your life!