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Ingredient dictionary

Lactic Acid

Also listed as: Milk Acid

Lactic acid is an alpha hydroxy acid, a mild acid that loosens dead skin cells and helps products hold water. It is on the label of 99 products in our library. Checked against our library November 6, 2026.

The catch: none for most people; check the full product list if your skin reacts easily.

What Lactic Acid does

  • Gently loosens dead skin cells
  • Helps skin hold water
  • Helps adjust a product's acidity

Lactic acid is a natural acid that the body makes and that also forms when milk sugar ferments, which is how it got its name. Much of the lactic acid used in cosmetics is made by fermenting sugars, though some is made synthetically. It belongs to the alpha hydroxy acid family, a group of mild acids often used to smooth skin.

Formulators like lactic acid because it is one of the gentler AHAs. It loosens bonds between dead skin cells so they wipe away more easily. It is also part of skin's natural moisturizing factors, so it helps skin hold water. In rinse-off products like body wash, it mainly keeps the formula at a skin-friendly acidity.

Good for

People who want gentle exfoliation and extra softness, especially those who find stronger acids too harsh.

Be careful if

Nothing in particular for most skin types.

Frequently asked questions

Is lactic acid good for sensitive skin?

It is one of the gentler acids, so many people with sensitive skin tolerate it well. Any acid can still sting, especially at first. Start slowly and patch test a small area before full use.

Does lactic acid make skin more sensitive to the sun?

Like other AHAs, lactic acid can make skin more sensitive to sunlight, because it loosens the outer layer of skin. Daily sunscreen is a good habit when using it.

Products with Lactic Acid

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