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Everything You Need to Know About AHAs vs. BHAs

Photo credit: Guido Mieth - Getty Images
Photo credit: Guido Mieth - Getty Images

From Good Housekeeping

If your skin is in desperate need of a radiance boost, there's a simple solution: regular exfoliation. But before you start scrubbing the heck out of your face, let's start with the basics. Exfoliators come in two different forms, chemical and mechanical. Face scrubs, for example, are mechanical exfoliators that physically rub away dead skin with small beads, as are scrubbing tools like brushes. Both chemical and physical exfoliation removes dead skin cells, which improves skin texture, and can keep acne and signs of aging at bay. But mechanical exfoliation may cause micro-tears in ultra-sensitive skin — in which case, chemical exfoliation is a gentler alternative that can help you achieve a glowing complexion.

While the word "chemical" might sound a tad scary, alpha-hydroxy acids (AHAs) and beta-hydroxy acids (BHAs) are simply acids that gently unclog pores by removing dead skin cells, leading to more even skin pigmentation, improved texture, and decreased inflammation. But what's the difference between AHAs and BHAs? Neither is "better" than the other; the best one to use just depends on your skincare needs. While there is some overlap in their benefits, the answer to whether you should be using AHAs or BHAs depends on your skin type and the results you hope to achieve.

No matter what product you end up choosing, it's important to start slow. Both AHAs and BHAs usually range in concentrations from around 0.5 to 20 percent. When you first begin adding acids to your skincare routine, start with a low concentration and use only once or twice a week. After your skin adjusts, you can raise the concentration of the acids you're using and how often.

⚠️ Safety tip: With any chemical exfoliant, you'll want to start with a lower concentration and work up to daily use. When using AHAs or BHAs, also remember to wear sunscreen with an SPF level of at least 30 every day to prevent sun damage, since topical acids make skin more sensitive to the sun.

What are AHAs?

AHAs are derived from fruits or sugar cane, which is why you may sometimes see them referred to as fruit acids. They're water-soluble, which means they work on the skin's surface to slough off the top layer of dead skin to reveal the smoother, more evenly pigmented layer of skin below. They also stimulate collagen production, which makes AHAs a good choice if anti-aging is your number one concern. AHAs are also best for people with dry skin.

"Alpha-hydroxy acids are safe for most skin types, but I tend to caution those with darker skin tones to start low due to the risk of superficial chemical burns," says Dr. Dhaval G. Bhanusali, a dermatologist based in New York City. "With glycolic acid specifically, we've seen superficial burns in darker skin types."

Benefits of AHAs

  • Fades sun spots, melasma, mild acne scars, and other forms of hyperpigmentation

  • Tackles signs of aging, such as wrinkles and fine lines

  • Brightens dull skin

Types of AHAs

  • Glycolic acid: The most popular type of AHA, glycolic acid is a powerful acid derived from sugar cane. Because of its efficacy and strength, you'll find this acid in most products touting AHAs on the label.

  • Lactic acid: Like glycolic acid, lactic acid works by removing the top layer of dead skin from your face. However unlike glycolic acid, lactic acid is derived from lactose in milk, instead of fruit acids.

  • Malic acid: Unlike lactic and glycolic acids, malic acid isn't all that effective on its own, so you won't see many products featuring this acid alone. However, this BHA-AHA crossover acid is often found alongside either glycolic or lactic acid for an extra boost of exfoliation.

What are BHAs?

BHAs are very similar in chemical structure to AHAs. But unlike AHAs, BHAs are oil-soluble, which means they can go deep inside your pores to target oil glands and decrease oil secretion. Because BHAs work to eliminate two of acne's best friends (excess oil and dead skin), this acid is best for preventing pimples in those with acne-prone skin. It's also recommended for people with greasy skin, since this acid decreases oil secretion.

"This ingredient is used as an OTC exfoliating active for acne, so you can find it in many products claiming to treat acne," says GH Beauty Lab chemist Danusia Wnek. The most common BHA you'll find while checking the label of acne-fighting products is salicylic acid.

Benefits of BHAs

  • Fights acne by unclogging pores

  • Calms down skin redness and fades inflammation

  • Decreases oil secretion

Types of BHAs

Salicylic acid: By far the most common type of BHA, salicylic acid is best known for its acne-fighting abilities. Since BHAs remove the pore-cloggers that lead to acne, salicylic acid is best for preventing blackheads and whiteheads.

Citric acid: This acid can actually be classified as either an AHA or a BHA, but for tackling excess oil, it's super effective when paired with salicylic acid.

Can you use AHAs and BHAs together?

In short, yes — especially if you're looking to fight acne. While BHAs will work to keep acne from forming, AHAs will decrease inflammation and get rid of the red marks that acne leaves behind.

While there are products that combine AHAs and BHAs together, if your skin is on the sensitive side, you may want to consider applying these acids separately, by applying one in the morning and one at night, or alternating which days you apply each.

⚠️ Safety tip: While retinol is also an anti-aging superstar, you do not want to combine retinol products with acids of any kind, as it can overwhelm your skin. "Retinol is strong as is, and combining it with chemical exfoliants may lead to red, irritated skin," says Dr. Bhanusali.

Just don't forget to apply moisturizer afterwards. "You exfoliate out the dead skin [when using acids], and moisturizing can help support the new skin growing in place," explains Dr. Bhanusali.


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