What does alpha hydroxy acid do for skin?

What AHAs do for skin

As skin renews, older cells leave the surface and newer ones replace them. AHAs encourage that shedding by loosening the attachments between surface cells. The skin underneath can look fresher, with more even texture and colour. The skin sheds surface cells on its own, so an AHA is an assistant, not the entire maintenance department.1

Glycolic and lactic acid products are also used to improve fine lines and signs of sun damage. With higher concentrations and sustained use, AHAs can affect deeper skin layers and support collagen and elastin production, which can make fine lines less obvious. This deeper effect is not the same as the surface exfoliation every AHA product provides; concentration, pH and time on skin all matter.12

What are alpha hydroxy acids?

AHAs are a group of organic acids used in skin care. Common examples are glycolic acid, lactic acid, citric acid, malic acid and tartaric acid. Products use different acids, strengths and formulas, so the name AHA alone does not tell you how a product will exfoliate. An AHA is a family name, not a strength, so the label still has to do its homework.2

Who may benefit from AHAs?

AHAs are used for roughness, fine lines and uneven tone. Glycolic acid may also help acne prone skin. Lactic acid is often chosen for dry skin because it has hydrating properties, but exfoliation itself can dry or irritate skin. People with dry or sensitive skin can start with a mild chemical exfoliator rather than a stronger treatment. More aggressive exfoliation can increase dark spots, particularly in people whose skin tends to develop marks after irritation or injury.134

How to use an AHA

1. 1Check the product label for how much to apply, how long to leave it on and how often to use it. Different formulas and exposure times change the effect, so do not borrow directions from another AHA product.
2. 2Leave on AHA products are generally used at night. Follow the product's own schedule; more aggressive exfoliation should be done less often.
3. 3For a rinse off exfoliator, apply gently in small circles for about 30 seconds, then rinse well with lukewarm water. Follow with moisturizer, since exfoliation can dry skin.
4. 4Use sun protection while using an AHA. A nighttime application does not remove the need for daytime protection.

What can you use with an AHA?

Prescription retinoid creams, retinol and benzoyl peroxide can make skin more sensitive or cause peeling. Exfoliating while using them can worsen dryness. Some skin care routines alternate AHAs with retinoids or vitamin C; if your routine already includes a retinoid or benzoyl peroxide, account for the added risk of dryness before combining them.4

What to expect, and how long it takes

Regular use can gradually improve surface texture and tone. A professional AHA peel retextures skin over a few months; its strength and schedule depend on skin sensitivity. Leave on products vary in concentration and formula, so there is no single timeline that fits every AHA product.1

What irritation should you stop for?

Redness, dryness, burning, itching, swelling and peeling are possible reactions. Stop exfoliating if your skin becomes persistently red or irritated, and do not use an exfoliator on sunburned skin or open cuts. If burning, swelling or a rash persists, or you are unsure whether exfoliation suits your skin, ask a dermatologist.24

Topical AHA treatments are considered safe in pregnancy. This refers to AHAs generally, not every ingredient that might appear in a particular product.1

Are AHAs good for dry skin?

Lactic acid is a common AHA choice for dry skin because it has hydrating properties. AHAs still exfoliate, and exfoliation can make skin dry or irritated. Choose a mild formula, follow its directions and apply moisturizer after exfoliating. A stronger product is not a shortcut to hydration.3

How often can you use AHAs?

There is no schedule that fits every AHA product. Frequency depends on the product, the exfoliation method and your skin; stronger or more aggressive exfoliation needs less frequent use. Follow the label rather than increasing use because your skin has not changed quickly. Leave on products are generally applied at night, and professional glycolic peels are commonly repeated at intervals of one to two weeks. That peel schedule is for a treatment, not a leave on product.14

Can AHAs make skin sensitive to the sun?

Yes. AHAs can increase skin sensitivity to ultraviolet light and the possibility of sunburn. Use sunscreen, wear protective clothing and limit sun exposure while using an AHA and for one week afterwards. The increase in sensitivity reverses after use stops; research found no significant difference in UV sensitivity one week after treatment ended.5