What does glycolic acid do?

Glycolic acid is an alpha hydroxy acid, or AHA, used in skincare for exfoliation. AHA products promote shedding at the skin surface and are used for smoother-looking skin texture. Its page also notes that the extent of exfoliation depends on the acid type, concentration, product pH and other ingredients. A percentage alone therefore cannot predict how gentle or strong a formula will feel.

How to assess a product

A wash-off formula, a daily leave-on product and a professional peel have different exposure patterns. Follow the specific label and avoid assuming that more frequent use will improve the result. AHA products may cause irritation, peeling or other reactions; stop use and seek advice if concerning symptoms persist. AHAs can increase sensitivity to sunlight; use sun protection during use and for a week afterward. A daytime broad-spectrum sunscreen is a practical part of a sun-safe routine.

Compare glycolic acid with the related AHA lactic acid and the BHA salicylic acid; they are not interchangeable simply because all are described as exfoliants. Cosmetic appearance claims differ from treatment claims such as treating acne or removing scars, which may make a US product a drug. Evaluate the actual product claims, not only the ingredient name.

Exfoliation depends on the entire formulation

Glycolic and lactic acids are common AHAs in cosmetic products. It says AHA products cause shedding of surface skin, with the extent depending on AHA type and concentration, product pH and other ingredients. That is why a prominently displayed acid percentage alone cannot rank the intensity of every cleanser, leave-on serum and peel. The page also notes AHAs may sometimes be used to adjust a product’s pH, so the mere ingredient-list appearance of glycolic acid does not prove that the finished product has been demonstrated to exfoliate in a particular way.

Read appearance claims and therapeutic claims separately

AHA cosmetics may be marketed for smoother-looking skin, while products intended to treat acne, remove scars or have other therapeutic effects may be regulated as drugs in the US. A glossary can explain cosmetic exfoliation without endorsing an unspecific glycolic-acid product for treating scarring or disease. The distinction is about a finished product’s intended use and claims, not a universal legal status assigned to the molecule. These US regulatory examples should not be described as rules for every country.

What the safety evidence does and does not show

Reported adverse reactions to AHA products include burning, rash, swelling, peeling and irritation; reports alone do not establish how often these occur. Those reports are signals, not a population-wide probability of reacting to any one formula. A comparison of AHA-containing cream with cream without AHA found that increased sensitivity to UV-related redness was observed after repeated application, while the comparison showed no significant difference one week after stopping in that study. This does not justify a blanket claim that all products confer identical UV sensitivity. Use sunscreen and protective clothing, and limit sun exposure during AHA use and for a week afterward. Follow the product label and seek advice for concerning reactions. The related lactic-acid and salicylic-acid pages offer useful comparisons, not proof of equal strength or equal tolerability.