4 Reasons Why You Should Use Lactic Acid

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Lactic acid may take a backseat to more “popular” alphahydroxy acids (AHAs) like glycolic acid, but that doesn’t mean it’s less significant when it comes to skin care. In fact, lactic acid is just a "lighter, gentler version of glycolic acid,” says New York dermatologist and founder of Entière Dermatology Melissa Kanchanapoomi Levin, MD. Here are four things you should know about this super versatile ingredient.

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1. It’s more moisturizing than other AHAs.
“Lactic acid is not only a gentler acid, but it also increases the skin's moisture level while still exfoliating it,” explains Dr. Levin. “At higher concentrations, lactic acid works well as an exfoliating ingredient to break up connections between skin cells, while at lower concentrations, it works as a humectant, which means it has the ability to pull water into the outer layer of the skin.” In addition to its ability to hydrate dry skin, “lactic acid is also great for minimizing fine lines and pigmentation due to its exfoliating properties,” says Brigitte Beasse, Los Angeles celebrity esthetician and owner of Brigitte Beauté.

2. It’s a good option for sensitive skin.
Lactic acid is a larger molecule size compared to glycolic acid, which makes it less potent and more tolerable. Lactic acid not only stimulates the exfoliation of skin cells, but also increases ceramides, an important fatty acid in your skin to serve as a protective skin barrier. Regardless of its gentleness, Joshua Ross, aesthetician and founder of SkinLab in Los Angeles, always recommends doing a small patch test behind the ear or on the inner arm first to make sure it doesn’t cause an allergic reaction. “After applying, wait 24 hours and see if you have a reaction, as some people do have an allergy to it,” he says. Beasse adds that because lactic acid is naturally found in milk, for those with milk intolerance, they should look for or synthetically derived or sugar cane–derived lactic acid instead.

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3. It shouldn’t be combined with certain actives.
Experts warn that just like any other alphahydroxy acids, it is important to not combine lactic acid with active ingredients such as “retinoids, vitamin C, betahydroxy acids and other alphahydroxy acids to avoid irritation, dryness, flaking or redness,” says Ross. “Too many acids on the skin can increase its sensitivity.” To make sure it plays nice with your existing routine, Dr. Levin says to “start using the product once or twice weekly to ensure that it does not cause irritation, and then increase the frequency to suit your skin.”

4. It’s not always the star ingredient.
Sunday Riley Good Genes (a personal fave; $105) puts lactic acid center stage, but not all products do, and it doesn’t make them any less effective. Dr. Levin likes SkinBetter AlphaRet Overnight Cream ($120), which combines lactic with glycolic, as well as a retinol, which “really highlights the beauty of lactic acid and how versatile it is.” Ross says his go-to is The Ordinary Lactic Acid 10% + HA ($7) because “it’s affordable and blends lactic with hyaluronic acid, so it exfoliates and immediately hydrates the skin.” Beasse is a fan of Environ, and likes its Tri Bio-Botanical Revival Masque ($81), which uses lactic acid to hydrate skin and lighten the appearance of pigmented marks.