Glycolic Acid (AHA)
- Effective dose
- 5–10 %
- Evidence
- 4/5· Strong
Last updated June 1, 2026
What it is
Glycolic acid is the smallest alpha-hydroxy acid, allowing it to penetrate readily and loosen the bonds between dead surface cells to promote exfoliation. With consistent use it stimulates collagen production and epidermal renewal. It is water-soluble and works best on the skin surface, making it a workhorse for texture and tone.
Benefits
Daily low-strength glycolic acid improves skin texture, discoloration, and signs of photoaging, while higher-strength peels yield more pronounced resurfacing. At-home leave-on formulas are commonly effective around 5-10% (buffered near pH 4), with in-office peels using much higher concentrations.
When to take it
Apply at night and always follow with morning SPF, since AHAs heighten photosensitivity. Start a few times per week and increase gradually as tolerated.
Side effects
Glycolic acid can cause stinging, redness, dryness, and peeling, and it increases sun sensitivity. Higher concentrations raise the risk of irritation and, in darker skin tones, post-inflammatory hyperpigmentation.
Sources
Products containing Glycolic Acid (AHA)
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