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Ingredient glossary
AHA (Alpha Hydroxy Acid): What It Is and What It Does
AHA stands for alpha hydroxy acid, a family of water-soluble exfoliating acids derived from fruit or milk sugars. Glycolic acid, from sugar cane, and lactic acid, from milk, are the two most common in skincare. AHAs work on the skin's surface to loosen the bonds holding dead skin cells together, supporting smoother-looking texture and more even tone.
What it does
AHAs dissolve the bonds between dead skin cells sitting on the surface, encouraging them to shed more evenly than they would alone. Glycolic acid has the smallest molecule of the common AHAs, so it penetrates most readily and tends to be the most potent; lactic acid is larger, generally gentler, and also acts as a humectant, drawing in moisture as it exfoliates. Because AHAs work across the whole surface rather than inside individual pores, they are typically chosen for overall texture, dullness and fine lines rather than congested pores specifically.
Who it suits
AHAs generally suit normal, combination and sun-tolerant skin looking to address rough texture, dullness or uneven tone, since their exfoliating action works across the whole surface. Lactic acid's gentler, moisturising profile makes it a reasonable starting point for drier or more sensitive skin, while glycolic acid's stronger, faster action suits skin that already tolerates exfoliation well. Very reactive, broken or sunburnt skin should avoid AHAs until it has recovered.
Cautions
AHAs increase skin's sensitivity to sunlight, so daily sunscreen is essential during use. Overuse or stacking multiple exfoliating acids in one routine commonly causes redness, stinging or peeling, particularly with glycolic acid. They should not be combined with retinol on the same evening. Anyone with a persistent skin condition should consult a pharmacist or dermatologist rather than self-treating with cosmetic acids.
Products with AHA (Alpha Hydroxy Acid)
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fragrance-free
- fragrance-free
Frequently asked questions
- What is the difference between AHA and BHA?
- AHAs are water-soluble and work on the skin's surface, making them suited to texture and dullness, while BHA (salicylic acid) is oil-soluble and can penetrate into oil-filled pores, making it more suited to congestion and blackheads. Some routines use both, on different days, rather than combining them in one application.
- Can I use AHA every day?
- Most people use AHAs two to three times a week rather than daily, particularly with stronger formulas like glycolic acid, building up gradually as skin's tolerance becomes clear. Daily use is more common with very low-strength, gentler lactic acid formulas, but sun protection remains essential regardless of frequency.
- Which AHA is better, glycolic or lactic acid?
- Neither is universally better — glycolic acid's smaller molecule makes it more potent and faster-acting, while lactic acid is generally gentler and also draws in moisture. Sensitive or dry skin often tolerates lactic acid more comfortably, while skin already used to exfoliation may prefer glycolic acid's stronger effect.
This is general information about a cosmetic ingredient, not medical advice. It does not describe any specific product, and does not diagnose, treat or cure any condition. If you have a persistent skin or scalp concern, speak to a pharmacist, GP or dermatologist. See our editorial policy for how we handle claims.