Glycolic acid (AHA): what it does and how to use it
Glycolic acid is the smallest alpha hydroxy acid (AHA). It loosens dead skin cells for smoother, brighter skin, and it makes skin more sensitive to the sun.
What it does
- Dissolves the bonds between dead cells on the surface.
- Improves rough texture, dullness and uneven tone.
- Mandelic acid is a larger AHA that works more slowly and gently.
Strength and rules
- The US Cosmetic Ingredient Review panel found glycolic and lactic acid safe at 10% or less with a final pH of 3.5 or higher, when the product protects against or warns about sun sensitivity.
- In FDA-cited research, four weeks of AHA use raised sensitivity to UV redness by 18%; the effect faded after stopping.
How to use it
- Start two or three evenings a week.
- Use sunscreen daily while using it and for a week after you stop, as the FDA recommends.
- Do not combine with retinol on the same night at first.
Who should be careful
- Stinging, redness and peeling mean you are overdoing it. Cut back.
Sources
General information, not medical advice. If you have a skin condition or are pregnant, ask your doctor.