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Lactic Acid

What Lactic Acid is & what it does

A gentle alpha-hydroxy acid that exfoliates while also hydrating, smoothing texture and evening tone with less irritation than glycolic acid. It suits drier and sensitive skin.

What is Lactic Acid and what does it do in sunscreen?

Lactic Acid is a gentle alpha-hydroxy acid (AHA). In a leave-on treatment it exfoliates and hydrates, smoothing texture and evening tone with less sting than glycolic acid. In most sunscreens, though, it appears in tiny amounts as a pH adjuster, fine-tuning the formula's acidity so it stays skin-friendly and stable rather than acting as an exfoliant.

Is Lactic Acid safe?

Yes. Lactic acid is a well-studied, widely used cosmetic ingredient and occurs naturally in the body and in fermented foods like milk. At the small, pH-balancing amounts used in a sunscreen it is non-irritating for most people. Used as a strong AHA exfoliant it can make skin more sun-sensitive, which is one reason daily sunscreen is recommended alongside acids.

Does Lactic Acid clog pores?

Generally no. It is a small, water-soluble acid rather than a heavy oil or wax, and it is not flagged as comedogenic. As an exfoliant it actually helps keep pores clear by loosening dead surface cells.

Does Lactic Acid exfoliate the skin in a sunscreen?

It can at the higher concentrations used in dedicated treatments, but in a sunscreen it is usually present at trace levels purely to balance pH. At those amounts it will not meaningfully exfoliate, it just keeps the formula at a skin-friendly acidity.

Is Lactic Acid natural or synthetic?

Both versions exist. Lactic acid occurs naturally and the cosmetic grade is typically produced by fermenting sugars, so it is often described as naturally derived. The finished ingredient is identical whether fermented or made synthetically.

Sunscreens with Lactic Acid

We rate 272 sunscreens that contain it, showing the top 10 by overall score:

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