AHAs (Alpha Hydroxy Acids)

What it is

AHAs (alpha hydroxy acids) are a family of water-soluble exfoliating acids derived from sources like sugar cane (glycolic acid) or milk (lactic acid). They work by loosening the bonds between dead cells on the skin's surface, encouraging them to shed more evenly. Different AHAs have different molecule sizes, which broadly affects how deeply and how quickly they act — glycolic acid's smaller molecule is generally considered more potent, while lactic acid is often positioned as milder and more hydrating.

What it does

AHAs work on the surface of the skin to loosen the bonds between dead skin cells, which is why they're commonly associated with brighter, smoother-looking skin.

Who it’s for

People interested in improving surface texture, dullness, or mild unevenness — generally most useful for normal-to-dry or sun-affected skin rather than very acne-prone skin, where a BHA is often favored instead.

Possible benefits

• Associated with smoother texture and reduced surface dullness
• Can help support a more even-looking tone over time
• Available across a range of strengths, from daily low-percentage formulas to occasional stronger treatments

Irritation & compatibility considerations

AHAs increase sun sensitivity, so daily SPF is considered essential alongside regular use. They can cause stinging, redness or flaking, especially at higher strengths or when introduced too quickly. They're not usually combined with retinoids or other strong acids in the same routine slot, and are generally avoided on visibly broken or compromised skin.

How it fits into a routine

Typically used at night, a few times a week to start, after cleansing and before moisturizer. Many routines treat AHA nights and retinoid nights as separate, alternating between them rather than combining both in one session.