Is lactic acid better than glycolic acid for sensitive skin?

Generally yes — its larger molecular size means slower penetration and less irritation, plus it has a built-in humectant effect that glycolic acid lacks.

Can I use lactic acid every day?

Many people tolerate 5% lactic acid daily, but those new to acids should start two to three times a week and build up tolerance.

Does lactic acid help with dark spots?

Yes, by speeding up cell turnover it helps fade post-inflammatory pigmentation and surface discoloration over consistent use.

Can lactic acid be used with retinol?

It's best not to layer them in the same session — alternate nights or use one in the morning and the other at night to limit irritation.

Is lactic acid vegan?

Traditional lactic acid is derived from milk sugars, but most commercial skincare uses a bacterial fermentation process from plant sugars, making it vegan — check the brand if this matters to you.

Lactic Acid — Ingredient Guide

How it works

Lactic acid is an alpha-hydroxy acid derived from fermented milk sugars (or produced synthetically for vegan formulations). Like other AHAs, it loosens the bonds between dead corneocytes on the skin's surface, encouraging faster, more even shedding. Its larger molecular size compared to glycolic acid means it penetrates more slowly, which is precisely why it tends to feel gentler. It's also a natural humectant, so it exfoliates and hydrates in the same step.

The evidence

Lactic acid has a long clinical track record, with foundational research demonstrating its ability to improve stratum corneum hydration, reduce visible signs of photoaging, and improve overall skin texture at concentrations used in professional and at-home peels. It's one of the most rigorously studied AHAs, second only to glycolic acid in the research volume behind it.

Suitability

I consider it the best entry-point AHA for dry, sensitive, or first-time acid users, since its hydrating side-benefit largely offsets the tightness other acids can cause. Acne-prone skin also tolerates it reasonably well, though salicylic acid remains the better-targeted choice for active breakouts.

Concentration

5% is an effective, well-tolerated daily concentration for most people; higher strengths (10%+) exist in at-home peels and move into professional-strength territory, where supervised use is safer.

Conflicts & combinations

Avoid stacking lactic acid with other exfoliating acids (glycolic, salicylic, mandelic, phytic) or retinol and benzoyl peroxide in the same routine — the cumulative irritation risk outweighs any added benefit. It pairs well with hyaluronic acid and ceramides to reinforce hydration and offset any residual dryness.