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Glycolic Acid

The smallest alpha hydroxy acid (AHA), used to chemically exfoliate the skin's surface and encourage smoother, more even-looking texture.

Source

Made from simple chemical building blocks (also occurs in sugar cane)

Used for

Surface exfoliation, smoother-looking texture

How it works

Glycolic acid is the smallest alpha hydroxy acid; it occurs naturally in sugar cane, and skincare grades are typically made by synthesis. Because it has the smallest molecular size of the commonly used AHAs, it penetrates the skin's surface more readily than larger acids like lactic or citric acid.

Once absorbed, it works by loosening the tiny structures (desmosomes) that hold dead skin cells together at the surface. Weakening that adhesion encourages dulling, built-up cells to shed more easily, revealing smoother, more even-toned skin underneath. In everyday leave-on skincare, this is a gradual, gentle form of exfoliation rather than the more intensive resurfacing of professional peels.

Glycolic acid is best introduced gradually (two or three evenings a week at first, building up as skin adjusts), since over-exfoliating can irritate rather than improve texture. Because it resurfaces the skin's surface, daily sun protection is essential while using it, and it's worth avoiding other strong exfoliating acids in the same routine.

01
Encourages the shedding of dull, built-up surface cells
02
Supports smoother-looking texture and more even tone over time
03
Can help improve the appearance of mild sun damage and post-blemish marks

Questions

What is glycolic acid?

Glycolic acid is the simplest alpha hydroxy acid (AHA), a small organic acid with just two carbon atoms. It occurs naturally in plants such as sugar cane, pineapple and sugar beet, but the glycolic acid used commercially is chiefly made by chemical synthesis rather than extracted from plants. It is widely used in cosmetics to improve the look of skin texture. (Lachaux et al., 2019)

How does glycolic acid exfoliate?

It loosens the connections between dead cells at the very surface of the skin. Research has shown it breaks down desmosomes, the tiny structures that bind surface cells together, only in the outermost, already-shedding layer, leaving the deeper layers of the skin's barrier intact so cells shed more readily from the top. (Fartasch et al., 1997)

Is there research on glycolic acid?

Yes, it is one of the most studied cosmetic acids. Research on human skin found it speeds up the natural renewal of the skin's surface layer, and a more recent laboratory study found that glycolic acid adjusted to a milder pH still encouraged shedding without increasing a marker linked to irritation. (Effendy et al., 1995; Narda et al., 2021)

Where it comes from

Glycolic acid is found naturally in a number of plants, including sugar cane, pineapple and sugar beet, which is why it is often described as a fruit or sugar acid. (Lachaux et al., 2019)

Most glycolic acid used today, however, is made by chemical synthesis rather than extracted from plants. (Lachaux et al., 2019)

Good to know

AHAs such as glycolic acid can temporarily make skin more sensitive to the sun, an effect that fades within a week of stopping. Wear a daily SPF while using it, and introduce it gradually if your skin is easily irritated. (US FDA)

The research