Everything you need to know about lactic acid—the alpha hydroxy acid that'll change your skin for the better.

By Amanda Lauren
July 16, 2019
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With so many skincare ingredients flooding our consciousness and our online carts, keeping track of the anti-aging products that promote flawless skin is practically a full-time job. One such skin-boosting ingredient that's on our radar: lactic acid. While you may associate the term with milk or muscle recovery, lactic acid is so much more than a common compound.

What is lactic acid?

Lactic acid is an alpha hydroxy acid (AHA) derived from dairy-based sugars. Simply put, it's a gentle chemical exfoliant that penetrates the top layers of one's skin. While incredibly affective, lactic acid isn’t anything new or revolutionary. In fact, the skin-boosting ingredient has been popular for centuries (Cleopatra was rumored to cleanse her face with milk).

“Lactic acid is one of my favorite topical agents because it's more forgiving and less irritating than salicylic acid, and it can be used to treat common acne and skin rosacea," says Jennifer Segal, MD, a board-certified dermatologist and founder of Metropolitan Dermatology Institute in Houston.

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How does lactic acid work exactly?

Lactic acid works by stimulating the skin's surface to interfere with the bonds between cells. When this process occurs, lactic acid promotes cell turnover and natural skin exfoliation by sloughing off dead cells, leaving you with brighter complexion.

What products can I find lactic acid in?

Most skincare products that contain lactic acid combine the AHA with other powerful, active ingredients, like retinol or hyaluronic acid. The combination has proven to be incredibly useful for treating skin hyperpigmentation, since lactic acid helps fade dark spots over time.

One popular product packed with lactic acid is The Ordinary Lactic Acid 10% + HA 2% ($7; sephora.com), a top-rated (and wallet friendly) anti-aging serum that combines lactic acid with hyaluronic acid. The combination is particularly ideal for dry skin types, since it gently exfoliates the outer layer of skin while drawing moisture in.

You'll find the powerful acid in chemical peels as well, including at-home peels like Dr. Dennis Gross Skincare Alpha Beta Universal Daily Peel ($88; sephora.com). These single treatment wipes contain two separate pads that combine lactic acid with glycolic, malic and salicylic acids. They're formulated to be used daily, so you can reap the benefits of a morning glow without visible inflammation.

RELATED: Hyaluronic Acid is the Anti-Aging Ingredient You Need for Glowing Skin

Does lactic acid work on all skin types?

Lactic acid is useful for all skin types, however the AHA can increase overall skin sensitivity. Avoid redness and irritation by starting with a small amount of lactic acid to gauge just how your face and neck will react.

How often should lactic acid be used to see its effects?

Lactic acid products should only be used once or twice a week, maximum. You may also need to switch up the rest of your skincare routine while using lactic acid, especially if you use harsher products or other exfoliants, like retinols. Read product labels carefully, and opt for gentle cleansers and daily moisturizers when using a lactic acid product.

As a result of regular lactic acid use, your skin will likely become more susceptible to the sun. To help combat sunburns and skin damage, protect your face with sunscreen (and reapply on the regular).

Sunday Riley Good Genes All-In-One Lactic Acid Treatment

Sunday Riley Good Genes lactic acid treatment

To buy: $105 for 1-ounce; sephora.com.

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