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Surprise! Acids are actually great for your skin

Everything you need to know about AHAs, BHAs, and PHAs.

A person looking into a mirror and applying skincare to their face. Credit: Getty Images / LaylaBird

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When you think of acids, your mind may conjure up visions of the periodic table and a chalkboard in your long-ago chemistry class. And the idea of putting a science experiment on your face sounds, well, appalling. But there are a number of acids that work to even your skin’s complexion in texture and tone.

The three types of acids are alpha hydroxy acids (AHAs), beta hydroxy acids (BHAs), and polyhydroxy acids (PHAs), says Dr. Sandhya Deverapalli, a dermatologist and the director of chemotherapy and transplant dermatology at Tufts Medical Center in Boston. Below, you’ll learn about the most common types under each of those categories—and how to figure out which is right for your skin.

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What are alpha hydroxy acids?

An older person holding a skincare bottle with the dropper against their skin.
Credit: Getty Images / yacobchuk

Alpha hydroxy acids are known for reducing discoloration.

AHAs are derived from foods such as fruit and milk. AHAs exfoliate the surface of the skin and are best suited for those who want to lighten discolored skin and reduce fine lines and wrinkles. While this acid type is gentle in OTC doses, Deverapalli recommends using AHAs sparingly if you have skin conditions such as eczema or rosacea that make your skin more sensitive.

Glycolic acid: Glycolic acid is an exfoliant derived from sugarcane. It’s approved by the FDA as a topical treatment for hyperpigmentation (an overproduction of melanin) or photodamage from sun exposure. It can also improve the skin’s texture by exfoliating the outer layer of skin. This ingredient is common in salon treatments, such as chemical peels, and in OTC skincare products, like serums.

Lactic acid: Lactic acid can be derived from milk or fermented vegetables. The acid is effective at firming the skin and smoothing out fine lines and wrinkles as a result. At the same time, it exfoliates the skin and can assist in evening out the tone in addition to texture.

Mandelic acid: This acid type, derived from almonds, is known for treating acne and hyperpigmentation, but one study found that mandelic acid can also improve the skin’s elasticity and firmness.

Products to try that contain AHAs

For skin brightening: The Ordinary Glycolic Acid 7% Exfoliating Toning Solution

To reap the exfoliating, skin-lightening benefits of glycolic acid, try this toner from The Ordinary. In addition to 7% glycolic acid, the toning solution contains a Tasmanian pepperberry derivative to reduce irritation and ginseng root and aloe vera to soothe and “offer visible radiance.” Apply the toner to a cotton pad and dab it onto clean skin in the evenings.

Get The Ordinary Glycolic Acid 7% Exfoliating Toning Solution from Sephora for $8.70

For reducing fine lines: The Ordinary Lactic Acid 10% + HA 2% Exfoliating Serum

If your concern is more on smoothing out fine lines and wrinkles, try The Ordinary’s Lactic Acid 10% + HA 2% Exfoliating Serum. The serum contains 10% lactic acid, 2% hydrating hyaluronic acid, and Tasmanian pepperberry to mitigate skin irritation from the exfoliation. Apply this directly to clean skin at night.

Get The Ordinary Lactic Acid 10% + HA 2% Exfoliating Serum from Sephora for $6.80

For reducing redness: Selfless by Hyram Mandelic Acid & Rice Bran Gentle Exfoliating Serum

Treat acne and hyperpigmentation with this serum from skincare guru Hyram Yarbro’s Selfless by Hyram line that includes mandelic acid to exfoliate and brighten the skin, rainbow algae also to exfoliate, and salicylic acid to unclog pores. The brand recommends applying a dime-sized amount to the face and neck every other evening.

Get the Selfless by Hyram Mandelic Acid & Rice Bran Gentle Exfoliating Serum from Sephora for $24

What are beta hydroxy acids?

A person applying a white cream to the acne on their cheek.
Credit: Getty Images / Boyloso

Beta hydroxy acids can prevent acne.

This acid type is derived from willow bark, wintergreen leaves, and sweet birch trees. While AHAs can help acne-prone skin because of their exfoliating abilities, BHAs are thought to be better for oily and acneic skin because they are anti-inflammatory and penetrate deeper into the pores. Because mature skin loses oil over time, Deverapalli recommends using BHAs, namely salicylic acid, on younger skin that has “plenty of oils to replenish.” If you have sensitive skin or conditions such as eczema or rosacea, Deverapalli recommends either opting out of BHAs or using them intermittently. Salicylic acid is the most common type of BHA used in cosmetics—and therefore, there’s the most information about its effects on the skin—but others include beta hydroxybutanoic acid, tropic acid, and trethocanic acid.

Salicylic acid: Derived from willow bark, salicylic acid is the main acid in this category. It’s lipophilic, meaning it can get into the pores and dissolve acne-causing dead skin cells and oils. For this reason, it’s a common topical acne treatment.

Products to try that contain BHAs

For salicylic acid: Paula’s Choice 2% BHA Liquid Exfoliant

This liquid exfoliant from Paula’s Choice is a fan favorite for its ability to gently exfoliate the skin with salicylic acid while reducing irritation with green tea extract. It claims to brighten the skin, even the texture and tone, and unclog pores to prevent acne. The solution is gentle enough to use twice daily; pour it onto a cotton pad and dab all over the face or on breakout-prone areas.

Get the Paula’s Choice 2% BHA Liquid Exfoliant from Amazon for $29.50

What are polyhydroxy acids?

A person looking into a mirror touching their cheek.
Credit: Getty Images / SanyaSM

Polyhydroxy acids can help protect the skin and prevent signs of aging.

PHAs are lesser-known and have been called a “new generation of AHAs.” One study found that PHAs offer similar anti-aging effects as AHAs—such as smoothing fine lines and wrinkles and firming the skin—but without irritating skin conditions like rosacea. Deverpalli says PHAs can also stimulate growth and repair in the skin, thanks to its antioxidant properties. They also provide more moisture than AHAs. Of the three categories of acids, Deverapalli recommends PHAs for anyone wanting to prevent signs of aging.

Gluconolactone: This type of acid is derived from gluconic acid and it acts as a humectant, meaning it draws in and retains moisture. It also exfoliates the skin, like alpha and beta hydroxy acids. Studies show that gluconolactone can protect the skin from UV damage (but you shouldn't skip your sunscreen).

Lactobionic acid: Derived from lactose, lactobionic acid acts as a humectant to draw in moisture and is an antioxidant that protects the skin against environmental aggressors.

Galactose: Galactose is derived from sugar in lactose and is also linked with exfoliating and providing skin-protecting antioxidants.

Products to try that contain PHAs

For exfoliating sensitive skin: The Inkey List Polyhydroxy Acid (PHA) Gentle Exfoliating Toner

If you have sensitive skin but still want the chemical exfoliation acids can offer, try The Inkey List’s PHA toner that contains gluconolactone to slough off dead skin cells, niacinamide to control oil, and aloe vera to soothe skin. Apply the toner to a cotton pad and apply it to clean skin in the morning and at night.

Get The Inkey List Polyhydroxy Acid (PHA) Gentle Exfoliating Toner from Sephora for $10.99

For soothing dry skin: Neostrata Restore Bionic Face Cream

Try the Neostrata face cream to moisturize and soothe dry, sensitive skin. It contains a 12% blend of lactobionic acid and gluconolactone to exfoliate and hydrate the skin. Apply twice a day to clean skin for the best results.

Get the Neostrata Restore Bionic Face Cream from Amazon for $60

For improving texture and tone with a triple threat: Glossier Solution

The Glossier Solution combines glycolic and lactic acids (AHAs), salicylic acid (BHA), and gluconolactone (PHA) to address acne and an uneven texture and tone on the skin. It also contains glycerin and aloe to moisturize and soothe the skin as well as niacinamide to control oil. Once every three days, apply the solution to a cotton pad and pat it into the skin.

Get the Glossier Solution from Glossier for $24

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