AHA and BHA are two terms used to group acids – e.g. Lactic and glycolic acids are AHAs – small, water soluble molecules that exfoliate multiple layers of skin. BHAs are oil soluble and generally a little less irritating for sensitive skin, e.g. salicylic acid. The fact that this contains a blend of both (glycolic, lactic, citric, salicylic, and tartaric acids feature) means that it’s a super powerful solution that really packs a punch.