Is lactic acid gentler than glycolic acid?

Usually, yes. Lactic acid is a larger molecule that gets into skin more slowly, so it tends to feel milder, and it doubles as a humectant. It still raises sun sensitivity, so daily sunscreen is part of using it.

Can I use lactic acid every day?

Many leave-on formulas are designed for daily use, but it is worth building up gradually, a few nights a week at first, and watching how skin responds before moving to nightly use.

What should I avoid layering with lactic acid?

Retinoids in the same layer can be more irritating for sensitive skin, so many people alternate lactic acid and retinoid nights rather than stacking both at once.

Alpha hydroxy acid (AHA)

Lactic Acid

INCI: Lactic Acid·Studied at 5–12% (leave-on)·Moderate evidence

A larger, milder alpha hydroxy acid than glycolic that also acts as a natural moisturising factor, studied for the appearance of a smoother, brighter surface with more hydration and less sting. It is produced by fermentation (traditionally from milk sugars, now usually plant-derived) and shows up across the concentration spectrum, from gentle daily leave-ons to stronger in-office peels. Because it exfoliates and holds water at the same time, it is often the AHA recommended first for drier or acid-sensitive skin.

Studied for

·The appearance of a smoother, more even surface
·The look of brighter, more even tone
·The appearance of hydrated, less rough-looking skin
·The look of softened fine lines and texture with continued use

How it’s thought to work

Loosens the bonds between surface skin cells like other AHAs, and its larger molecule penetrates more slowly, which is studied for a gentler feel; it raises sun sensitivity, so daytime sunscreen matters. Its dual role as a natural moisturising-factor component means it also draws water to the surface as it exfoliates, part of why it tends to read as less drying than glycolic acid at a matched percentage.

Landmark study· studied at 15%

A 15% lactic acid and ceramide lotion was linked to smoother, less flaky looking, better moisturized skin after 14 days of use.

A 14-day Controlled Study Assessing Qualitative Improvement with 15% Lactic Acid and Ceramides in Skin Moisturization and Desquamation. Journal of Clinical and Aesthetic Dermatology, 2020.

View on PubMed (PMID 33178384) ↗

Layering note

Often kept apart from: retinoids in the same layer for sensitive skin.

Questions

Is lactic acid gentler than glycolic acid?: Usually, yes. Lactic acid is a larger molecule that gets into skin more slowly, so it tends to feel milder, and it doubles as a humectant. It still raises sun sensitivity, so daily sunscreen is part of using it.
Can I use lactic acid every day?: Many leave-on formulas are designed for daily use, but it is worth building up gradually, a few nights a week at first, and watching how skin responds before moving to nightly use.
What should I avoid layering with lactic acid?: Retinoids in the same layer can be more irritating for sensitive skin, so many people alternate lactic acid and retinoid nights rather than stacking both at once.

Serums we’ve scored with Lactic Acid

References

This dossier covers the efficacy evidence. For the safety and concern profile of Lactic Acid, see PlainBody ↗, our sister site.