A type of alpha hydroxy acid (AHA), also known as amygdalic acid. ThereŠ—Ès some research showing mandelic acid is an effective exfoliant, although itŠ—Ès not as effective as glycolic acid due to its larger size (itŠ—Ès twice as big as glycolic acid) and slower penetration into skin; however, these traits can also make mandelic acid more tolerable for those with sensitive skin. Unlike glycolic acid, mandelic acid is light-sensitive and must be packaged in an opaque container to remain effective. A couple studies have shown that mandelic acid and salicylic acid worked well together in a higher-strength peel for use on darker skin tones struggling with discolorations, including post-acne marks. However, what we donŠ—Èt know is how well mandelic acid wouldŠ—Ève worked on its ownŠ—”itŠ—Ès possible the results were more from salicylic acid than the combination of the two acids. Other research has shown mandelic acid can increase sebum (oil) production, which isnŠ—Èt great for oily skin but would be a benefit for dry skin. Reference for this information: Dermatologic Surgery, March 2016, pages 384-391; and January 2009, pages 59-65 Advances in Dermatology and Allergology, June 2013, pages 140-145