What it does: Salicylic acid is a BHA. It’s found in many over-the-counter acne products. Salicylic acid is also used as an active ingredient in gels which remove plantar warts (but you can also use banana peels to cure warts).

How to do it: Apply to problem areas. Let dry. It is generally safe to leave on. Salicylic acid is a BHA, and the molecules in BHAs are larger than AHAs. This makes it less able to penetrate too deeply into skin and keeps it very mild.

Why it helps: Salicylic acid is able to penetrate into the pore which contains sebum and exfoliate the dead skin cells that are built up inside the pore. Because of this difference in properties, beta hydroxy acid is better used on oily skin with blackheads and whiteheads.