Glycolic acid for skin concerns and body areas

Glycolic acid works on the surface: DermNet NZ explains that alpha hydroxy acids loosen the glue-like substances holding surface skin cells together (DermNet NZ). That is why the evidence differs from one concern to the next. Each guide below says what the evidence covers for that concern, and where it runs out.

The body is not one skin. Our working range for underarms and the bikini line is lower than for elbows and heels; the chart below sets the ranges side by side, and the statistics page adds the face.

How much acid each area takes, in our working ranges

Underarms 5–7% · 1–2x per week to start
Arms (KP) 7–10% · 1–2x per week to start
Legs 7–10% · 1–2x per week to start
Thighs (KP) 7–10% · 1–2x per week to start
Elbows & knees Up to 10% · 1–2x per week to start
Feet / heels Up to 10% · 1–2x per week to start
Bikini area 5–7% · 1x per week to start
Back 7–10% · 1–2x per week to start

These are our working ranges, not sourced standards: no source we read sets a glycolic acid concentration by body area. Paler bars are ceilings only ("up to"). The thin line marks 10%, the figure in the Cosmetic Ingredient Review panel's consumer conclusion as the FDA reports it. Notes for each area are in the body and underarm guide.

Bumps and texture

Glycolic acid for keratosis pilaris
Why KP bumps form, how an AHA helps loosen the plugs, and the concentration, routine and products, backed by research.
Glycolic acid for strawberry legs
What the dark dots after shaving actually are, whether glycolic acid helps, and how they differ from keratosis pilaris.
Glycolic acid for ingrown hairs and razor bumps
How it helps after shaving, waxing or epilating, safe timing around hair removal, and bikini-line specifics.
Glycolic acid for rough elbows, knees and heels
Why these areas thicken, how glycolic acid smooths them, and a realistic timeline for thicker skin.

Discolouration

Glycolic acid for dark spots
Post-acne marks, sun spots and melasma have different evidence, and irritation can itself cause marks. What the sources say for each.

By body area

Glycolic acid for underarms and the body
Concentrations by body area, a step-by-step routine, and the products that passed our checks.
Glycolic acid on the scalp
What it does for buildup, when it is the wrong choice for an itchy or flaky scalp, and how to apply it.

What to expect, and when

Glycolic acid before and after: a realistic timeline
When results start, concern by concern: texture, dark spots and acne scars, based on clinical studies.

Before you start on any of these

For keratosis pilaris the AAD recommends gentle exfoliation but also says to avoid scrubbing, which tends to irritate the skin and worsen KP (AAD self-care). And on any area, the FDA's own studies "confirmed previous industry studies indicating that applying AHAs to the skin results in increased UV sensitivity" (FDA), so cover treated skin that sees the sun. More in glycolic acid and sun exposure and using it on sensitive skin.

Last reviewed 2026-10-13.