There’s nothing I love more than nerding-out over skincare ingredients and skincare routines. While others jump straight to sampling a new product, I jump straight to reading the ingredients label first. And you know what I’ve learned over my career? That ish can get real confusing, real fast—especially when it comes to chemical exfoliants. Like, “alpha-hydroxy acid” (AHA) and “beta-hydroxy acid” (BHA) look pretty similar, right? But they’re distinctly different: One’s better for dark spots, and one’s better for getting rid of a pimple. One’s better for sensitive and dry skin, and one’s better for oily skin.
So if you plan on using either one, it’s important to know the difference between AHA vs BHA. And that’s where I, your favorite skincare nerd, come in. I chatted with a ton of dermatologists and skincare experts about AHAs and BHAs to help you figure out which one is best for your skin type and needs. Keep this nearby as your cheat sheet the next time you go to reach for that new acid to exfoliate your face.
Meet the experts:
- Adarsh Vijay Mudgil, MD, is a board-certified dermatologist and dermatopathologist at Mudgil Dermatology in New York, NY.
- Neal Schultz, MD, is a board-certified dermatologist at Park Avenue Skin Care and the owner of BeautyRX. Dr. Schultz has previously spoken to Cosmo about facial exfoliation.
- Saya Obayan, MD, is a board-certified dermatologist at Skin Joy Dermatology in Austin, TX. Dr. Obayan has previously spoken to Cosmo on the topic of glycolic acid serums.
- Shereene Idriss, MD, is a board-certified dermatologist and founder of Idriss Dermatology in New York, NY. Dr. Idriss has previously spoken to Cosmo about liquid exfoliant.
- Loretta Ciraldo, MD, is a board-certified dermatologist and owner of Dr. Loretta skincare. Dr. Ciraldo has previously spoken to Cosmo on the topic of skin texture.
- Mamina Turegano, MD, is the co-founder of Skintap.com and a board-certified dermatologist at East Jefferson General Hospital in New Orleans, LA. Dr. Turegano has previously spoken to Cosmo on the topic of acne body wash.
- Rachel Nazarian, MD, is a board-certified dermatologist at Schweiger Dermatology. Dr. Nazarian has previously spoken to Cosmo on the topic of salicylic acid.
What is AHA?
The abbreviation AHA stands for alpha-hydroxy acid, an acid primarily used as a chemical exfoliant or liquid exfoliant (as opposed to a physical exfoliant, like a gritty face scrub). The most popular AHAs are glycolic acid, lactic acid, mandelic acid, malic acid, and tartaric acid, and chances are, you’ve used them before. But if not, here’s how they work and who they’re best for:
The skin benefits of AHAs:
AHAs are superficial exfoliants (meaning they exfoliate the top layer of the skin) that help treat melasma, sun damage, acne, and superficial wrinkles (by stimulating collagen production), says dermatologist Adarsh Vijay Mudgil, MD. AHAs aren’t only good for fading hyperpigmentation—they’re also great for exfoliating the skin and preventing breakouts, according to dermatologist Shereene Idriss, MD, since they dissolve the glue between dead skin cells, helping to prevent clogged pores.
The best skin type for AHAs:
In addition to their exfoliating properties, AHAs are known for being somewhat hydrating at the same time—a plus for those with dry skin. And if you’re dealing with easily irritated skin, lactic acid is known for being a great AHA for sensitive skin (although you should always spot-test new products). As dermatologist Loretta Ciraldo, MD, previously told Cosmo, those with rough skin texture from very dry skin could benefit from using lactic acid (the most hydrating exfoliator in the AHA family) to hydrate as it exfoliates. If your skin can tolerate something a little stronger, try glycolic acid, which is one of the most effective AHAs.
Where to apply AHAs:
On your face, on your back, on your butt—you can even use AHAs on your feet in a foot mask. AHAs are super versatile and come in tons of different formats, like toners, peels, masks, or serums, but there’s no need to double up and use them in every single product (please don’t). Find a product type that works for you (those with longer contact time usually work best, but they can be more irritating), and stick with just that one.
How to use AHAs:
Board-certified dermatologist Saya Obayan, MD, previously told Cosmo that if you’re new to acids, the best way to incorporate them into your routine is to start with a low percentage of glycolic acid (like 5%), and slowly work your way to 15 or 20%. If you have sensitive skin, board-certified dermatologist Neal Schultz, MD, previously told Cosmo that you should start out applying a mild exfoliant such as lactic acid once a week for a few weeks and gradually increase to three to four times per week. If you need something stronger at that point, switch to glycolic acid.
What is BHA?
Now, let’s get into BHAs. This acronym stands for beta-hydroxy acids, and it’s also a chemical exfoliant. The most notable BHA is salicylic acid, but willow bark extract is a popular gentle alternative. Although there’s a slight overlap between the benefits of BHAs and AHAs, they’ve got some key differences, so let’s get into it.
The skin benefits of BHAs:
Chances are you’ve used salicylic acid a time or two on a pimple. Why? It’s one of the most common ingredients for treating whiteheads, but it also works for inflammatory acne as well. “Because salicylic acid is an anti-inflammatory ingredient, it also decreases the redness and irritation that comes with red, tender pimples,” board-certified dermatologist Rachel Nazarian, MD, previously told Cosmo. “And since it breaks the bonds between the skin cells, it also gently exfoliates your skin to help prevent the formation of acne.”
The best skin type for BHAs:
Thanks to their antibacterial properties and ability to penetrate deeply into the skin, BHAs are ideal for treating oily, acne-prone skin and enlarged pores, Dr. Mudgil explains. If you have naturally dry skin, rosacea, or eczema, use caution with salicylic acid and consult your dermatologist first.
Where to apply BHAs:
As a tried-and-true acne ingredient, sal acid is most commonly found in spot treatments, body washes, and cleansers for acne. Although you wouldn’t want to go overboard on BHA (irritation? No, thanks), you can apply salicylic acid in most places, like on your chest or even on your scalp with shampoo if you have dandruff or scalp acne.
How to use BHAs:
For the most part, OTC salicylic acid products will have concentrations somewhere between 0.5% and 2%, but JSYK, more does not always mean better. Much like retinoids or AHAs, start low and work your way up to a stronger concentration if your skin can handle it without irritation.
Which is better, AHA or BHA?
Reminder, this isn’t a competition. Just find what works for you and run with it. AHAs and BHAs are both fantastic for skin, but they might not be amazing for everyone (pls see the section above where we go over the ideal skin types for each acid). To sum it up, AHAs are better for dry skin and those looking to address pigmentation, while BHAs are better for oily skin and acne. And if you’re someone who has concerns that fall on both sides, you might want to consider using a product that contains both AHAs and BHAs. Whaaa?! You can do that?? Yup, you can use them both, but you want to be careful.
Can you use AHA and BHA together?
“For folks that have acne-prone skin or enlarged pores and sun-damage or pigmentation issues, a combination product is a good option,” Dr. Mudgil says. “The combination can be more irritating, though, so it’s important to be mindful of the effects on one’s skin.” Try only one chemical exfoliant at a time—at least at first—and see what your skin can handle. If you seem to tolerate exfoliants pretty well, use a product that contains both AHAs and BHAs instead of trying to combine them on your own.
The final word on AHA vs BHA
Neither ingredient is better than the other per se, but one might be better for you. As Dr. Mudgil explains, if your issues are sunspots and fine lines, you really only need an AHA-containing product. If you don’t have sun damage but do have enlarged pores or acne-prone skin, you likely only need a BHA-containing product. If you have sun damage and acne-prone skin or enlarged pores, a combination AHA/BHA product would be the most comprehensive solution. And remember, when we’re talking about exfoliating, especially if you’re just starting out or trying new products, less is best.
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