Which chemical exfoliant is best for treating acne?

BHA, or beta hydroxy acid, is particularly effective for treating acne due to its oil-solubility, allowing it to penetrate deep into the pores where acne often originates. BHA, most commonly in the form of salicylic acid, helps to dissolve excess sebum and dead skin cells that can clog pores, leading to breakouts. Additionally, it has anti-inflammatory properties that can help reduce redness and swelling associated with acne.

In contrast, AHA (alpha hydroxy acid) is water-soluble and primarily works on the skin's surface, making it more suitable for treating issues like sun damage and dry skin rather than deep-seated acne. PHA (polyhydroxy acid) also functions similarly to AHA but is milder and is used primarily for sensitive skin or for improving skin texture without the same level of acne-fighting properties as BHA.

Microdermabrasion is a physical exfoliation method that can help with mild acne, but it doesn't specifically target the internal causes of acne the way BHA does. Therefore, when considering the most effective chemical exfoliant for treating acne, BHA is the best choice.