AHA vs BHA: What's the Difference and Why Should You Use Them?

Audrey Noble

If you want healthy-looking skin, there are two very important acids you must familiarise yourself with: AHAs (alpha-hydroxy acids) and BHAs (beta-hydroxy acids). No acid is better than the other; they just target different needs. Plus, there are so many products that combine both ingredients that you can just tackle all those skin concerns at once (but we'll get to that later).

To break it down for us, we turned to Kenneth Howe, MD, a dermatologist at Wexler Dermatology. See what he was to say below. 

What are AHAs

AHA stands for alpha-hydoxy acids. "AHAs are derived from sugar cane or other plant sources, which is why they are often referred to as fruit acids," says Howe. He says that glycolic acid, which is the smallest of the AHAs and is derived from sugar cane, is the most widely used AHA in skincare products. 

AHA Benefits

"AHAs exert benefits both to the outer layer of the skin (epidermis) and the deep layer (the dermis)," says Howe. "In the epidermis, AHAs have an exfoliative effect, increasing the shedding of dead skin cells retained at the surface. They do this by gently cleaving the retained bonds between dead skin cells. Once cut loose, those cells can then fall off, or exfoliate."

AHAs also help stimulate collage production, which is why it is so important when wanting to reduce the appearance of fine lines. "AHAs do this both by increasing collagen synthesis by fibroblasts (the collagen-producing cells in the skin), and by decreasing degradation of the existing dermal matrix," he says. 

What are BHAs

BHA stands for beta-hydroxy acids. "They are organic carboxylic acids with one hydroxyl group attached to the beta position of the carboxyl group. So they differ from alpha-hydroxy acids in the position of the one hydroxyl group—but otherwise, they’re quite similar in structure," says Howe. The most common BHA that everyone fighting acne is very familiar with is salicylic acid. 

BHA Benefits

"Salicylic acid (SA) is fat-soluble, so it’s good on oily skin and gives it an enhanced ability to penetrate pores," says Howe. "These features explain why SA is used in a lot of OTC acne products."

He also says the salicylic acid is known to fight bacteria and can be used to treat calluses and other areas of dry skin. "In the highest concentrations, it is used to treat warts. It exerts this effect in a similar way to what AHAs do—by ungluing dead skin cells from each other—but salicylic acid penetrates deeply," he says. 

Now that you know the difference between the two, click through to see which AHA and BHA products you should be adding to your routine. 

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