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AHA vs BHA: What’s the Difference and How to Choose the Best Acid Exfoliant for Your Skin

Your guide to chemical exfoliation.

Exfoliation has long been the secret to glowing, healthy-looking skin. But you don’t need a harsh, gritty scrub to get the job done. Alpha- and beta-hydroxy acids are the best way to remove dead skin cells, using chemical (not physical) methods.

Also known as AHAs and BHAs, they’re the two most common families of exfoliating acids that you’ll see in skincare products—and they’re often found together. 

So how do they actually work? Which type is best for your skin? And can you get better results if you use both of them?

If you’ve been asking these questions, this tutorial is for you. You will learn the difference between AHAs and BHAs, how to choose the right one, and whether it’s beneficial to incorporate both types in one routine. I’m also sharing some of my favourite AHA and BHA products that I always recommend. 

What Is AHA?

Types of AHAs

These are the different types of AHAs that you will see in skincare products:

  • Glycolic acid: The most common AHA, derived from sugarcane. It is also the strongest, due to its small molecule size, but that makes it the most irritating, too.[4]
  • Lactic acid: The second most common AHA, derived from milk. It’s a gentler alternative to glycolic acid, and can be appropriate for sensitive skin.[4]
  • Mandelic acid: A mild AHA derived from bitter almonds. As it is weaker than lactic acid, it’s usually combined with other acids. However, some experts such as Dr. Loren Pickart believe it can be neurotoxic.[5]
  • Malic acid: A mild AHA derived from apples. Like mandelic acid, it won’t do enough on its own, so you’ll typically see it in combination with stronger AHAs.
  • Tartaric acid: A weak AHA derived from grapes. Instead of acting as an exfoliant, it is more often used to stabilize other acids’ pH levels.
  • Citric acid: A weak AHA derived from citrus fruits. It is similar to tartaric acid in that it regulates pH. It is also used as a preservative.
  • Phytic acid: A weak AHA derived from rice, seeds and grains. It is commonly used as an antioxidant.
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From The Skincare Edit Archives

What Is BHA?

Types of BHAs

The main BHA exfoliants you’ll see in skincare products are:

  • Salicylic acid: The most common BHA, and also the strongest. However, it is not as irritating as glycolic acid (the strongest AHA) because of its large molecule size and anti-inflammatory nature.
  • Betaine salicylate: A BHA comprised of salicylic acid and betaine (a hydrating amino acid derived from sugar beets). It’s a gentler alternative to salicylic acid, and according to data from the manufacturer, is equally effective.[10] (A 4% concentration of betaine salicylate is said to be equivalent to 2% salicylic acid.)
  • Salix alba or willow bark extract: A natural BHA derived from willow bark. The salicin content converts into salicylic acid, but it is much weaker (so it won’t give you as dramatic results).

How AHA and BHA Are Similar

How AHA and BHA Are Different

Should You Use AHA, BHA or Both?