Ingredient guide

AHAs (glycolic & lactic acid): what it does and how to use it

Updated November 2026

Safety first: general cosmetic information, not medical advice. Patch-test new products and follow label directions. Pregnant, breastfeeding, using prescription skin treatment or managing a skin condition? Ask your doctor before trying new actives. Medical disclaimer
In short: Water-soluble exfoliating acids that dissolve the bonds between dead surface cells, revealing smoother, brighter skin. Best used at night, introduced slowly. Top benefit: instantly brighter, smoother skin.

Water-soluble exfoliating acids that dissolve the bonds between dead surface cells, revealing smoother, brighter skin.

Best timeNight
StrengthActive (go slow)
Good forInstantly brighter, smoother skin

Benefits

Who it's for

Normal, dry and sun-damaged skin. Lactic acid is the gentler choice for sensitive skin.

How to use it

Use 2–3 evenings a week after cleansing. Leave-on toners or serums work best. Always wear SPF the next day.

Watch out for

Over-exfoliation shows up as stinging, shininess and redness. Pause all acids if it happens.

Best AHAs products

Night treatment$
The Ordinary Glycolic Acid 7% Exfoliating Toner

Gentle AHA exfoliation for brighter, smoother skin. Use 2–3 times a week.

AHAs
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Night treatment$$$
Sunday Riley Good Genes Lactic Acid Treatment

Lactic acid for an overnight radiance boost.

AHAs
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Can you mix AHAs with…

⚠️RetinolUse on alternate nights⚠️Vitamin CBetter at different times✅NiacinamideYes, generally fine together⚠️Salicylic acidFine in one product, careful when layering⚠️Benzoyl peroxideWatch for dryness✅Hyaluronic acidYes, generally fine together⚠️Azelaic acidGo slow⚠️PeptidesUse at different times✅CeramidesYes, highly recommended✅SunscreenEssential✅Tranexamic acidYes, generally fine together✅BakuchiolYes, generally fine together✅Centella (cica)Yes, generally fine together✅SqualaneYes, generally fine together

Routines that use AHAs

Glowing Oily SkinGlowing Dry SkinGlowing Combination SkinGlowing Normal Skin

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FAQ

What does AHAs do for skin?

Water-soluble exfoliating acids that dissolve the bonds between dead surface cells, revealing smoother, brighter skin.

When should I use AHAs, morning or night?

Use 2–3 evenings a week after cleansing. Leave-on toners or serums work best. Always wear SPF the next day.

Who should use AHAs?

Normal, dry and sun-damaged skin. Lactic acid is the gentler choice for sensitive skin.

This page is general cosmetic information for educational purposes. It is not medical advice, diagnosis or treatment, and it doesn't replace a dermatologist or other qualified professional. Product formulas change, so always read the label. Full medical disclaimer.