The primary difference between AHAs and BHA is that AHAs are water-soluble, while BHA is lipid-(oil) soluble. This unique property of BHA allows it to penetrate the oil in the pores and exfoliate accumulated skin cells inside the pore’s follicle lining that can clog them. BHA is best used where blackheads and blemishes are the issue, and AHAs are best for sun-damaged, thickened, dry skin where breakouts are not a problem. (Sources: Expert Opinion in Pharmacotherapy, April 2008, pages 955-971; Seminars in Cutaneous Medicine and Surgery, September 2008, pages 170-176; and Global Cosmetic Industry, November 2000, pages 56-57.)
What glycolic, lactic, and salicylic acids do is “unglue” the outer layer of dead skin cells, allowing healthier cells to come to the surface. You can expect almost immediate benefits from regular use of an AHA or BHA product, such as improved skin texture and color, unclogged pores, and moisturizers being better absorbed by the skin. Sun damage in particular causes the top layer of skin to become thicker, creating a dull, rough appearance on the surface of skin. Fortunately, both AHAs and BHA affect the top layers of skin, and they help to improve the appearance of sun-damaged, dry, and/or thickened skin. (Sources: Free Radical Biology and Medicine, May 17, 2008; InternationalJournal Cosmetic Science, February 2005, pages 17-34; Dermatologic Surgery, May 1998, pages 573-577; and Archives of Dermatologic Research, June 1997, pages 404-409.)