Alpha Hydroxy Acid

Lactic Acid

Lactic acid is an AHA with a larger molecular size than glycolic acid, resulting in slower penetration and less irritation. It has the added benefit of being a natural moisturising factor (NMF) component, providing exfoliation and hydration in one step.

topicalexfolianthydrationbeginner-friendly

Strong Evidence

Last reviewed: March 2026 · Our methodology

What It Does

Lactic acid (molecular weight 90 Da) dissolves the bonds between dead corneocytes in the stratum corneum, promoting cell turnover. Because it is larger than glycolic acid (76 Da), it penetrates more slowly and is generally better tolerated. Lactic acid is also a component of the skin’s natural moisturising factor (NMF), which means it contributes to hydration while exfoliating — a dual action that glycolic acid does not provide.

At concentrations of 5–12%, lactic acid improves skin texture, brightness, and mild pigmentation. At higher concentrations in professional peels, it can address more significant concerns.

Best Use Cases

Rough, dull skin texture
Mild pigmentation and uneven tone
Dry skin that needs exfoliation without further drying
First-time chemical exfoliation (gentler entry point than glycolic acid)

Who May Benefit Most

People with dry or sensitive skin who want the benefits of AHA exfoliation without the intensity of glycolic acid. Excellent as a first AHA for beginners. Also useful for those in dry climates where additional hydration is valuable.

Cautions

Increases photosensitivity — daily SPF 30+ is essential. Start at 5% concentration 2–3 times per week. Less irritating than glycolic acid but can still cause stinging on compromised or very sensitive skin. Not recommended during active retinoid adjustment.

Common Mistakes

Assuming 'gentler' means 'ineffective' — lactic acid produces meaningful results at appropriate concentrations
Using daily from the start — begin 2–3 times per week
Combining with retinoids in the same PM step without established tolerance
Skipping sunscreen

Combines Well With

Hyaluronic acid (apply after to boost hydration)
Niacinamide (calming and barrier support)
Ceramide moisturisers (restore barrier after exfoliation)

May Combine Poorly With

Retinoids in the same PM step (alternate nights)
Other exfoliating acids in the same step
Benzoyl peroxide in the same step

Realistic Timeline

Smoother texture within 2–4 weeks. Brightness and mild pigmentation improvement at 6–8 weeks. Consistent use over 3+ months for best results.

Disclaimer

Lactic acid increases sun sensitivity. Always use broad-spectrum SPF 30+ when using AHA products. Discontinue if persistent irritation, redness, or peeling occurs.