AHA vs. BHA: We Asked a Dermatologist to Explain the Difference Once and for All

Is it just us or is the skin-care term “acids” a little scary? Not to mention, with the different varieties (AHA vs BHA), it’s a little confusing, too. We tapped board-certified dermatologist Dr. Shari Sperling of Sperling Dermatology in Florham Park, New Jersey, to explain their differences and tell us exactly what they do, once and for all.

“Both AHAs and BHAs are acids that help to exfoliate the skin,” Dr. Sperling explains. “AHA stands for alpha hydroxy acid and comes most commonly in the form of glycolic acid and lactic acid. Because AHAs are water-soluble, they don’t penetrate far into the skin. Meaning they’re more superficial and help remedy surface-level concerns like anti-aging, acne scarring and pigmentation issues.” Dr. Sperling continues, “BHA stands for beta hydroxy acid, or salicylic acid as we know it. Thanks to its oil-soluble makeup, BHA penetrates deeper into the skin providing antibacterial and anti-inflammatory properties. BHAs are great for treating blemishes and acne-prone complexions.”

Although both AHAs and BHAs are acids, they’re used for different concerns. As Dr. Sperling explained, AHAs have an exfoliative effect, which helps to break the bonds between old skin cells so they can easily make way for new, healthy cells. AHAs also stimulate collagen production to help reduce the appearance of fine lines, wrinkles and hyperpigmentation. If you have dry, dull skin, AHAs are a great way to exfoliate the top layer of skin without further drying it out.

BHAs sink into skin to clean out excess sebum from pores and help to remedy blemishes, acne and an overproduction of oil. This explains why most over-the-counter acne products include salicylic acid—and why we all have likely heard of it before. So if you have oily, acne-prone skin, BHAs are probably for you.

Yes! Many products already contain a combination of both AHAs and BHAs. It’s especially beneficial to use them together if you suffer from cystic acne or have generally acne-prone skin and need to address scars from old blemishes while preventing new pimples from forming. The combination is also great for those of us in the 30-plus crowd that suffer from adult acne or oily skin and want to simultaneously address fine lines and wrinkles.

At the risk of potentially over-exfoliating your skin, AHAs should be used every other day at the most. Think about it: You don’t want to strip fresh, new skin cells day after day (ouch). For concerns like cystic acne, BHA is safe to use every day to help regulate oil production and keep painful blemishes from appearing.

Dr. Sperling recommends using both acids at night after cleansing and toning, because they increase sensitivity to sunlight. During the day, you should be extra diligent with SPF to protect those new skin cells from UV damage.

Yep! Even those with sensitive skin can benefit from AHAs and BHAs. Just make sure you start with a product that says it's suitable for sensitive skin and only use it every few days. Assuming no irritation occurs, you can work your way up to using it every day. 

Ready to get glowing? Shop Dr. Sperling’s and our AHA and BHA picks below.