Hydroxy Acids are very common active ingredients in skin care products to help reduce discoloration, improve acne and the appearance of fine lines, and give the skin a healthy, radiant glow. There are two basic types: Alpha and Beta Hydroxy Acids. Alpha Hydroxy Acids (AHAs) are a class of compounds that have been used for literally thousands of years (think Cleopatra taking a sour milk bath) to help improve the look and feel of the skin.
There are actually several different kinds of AHAs. Glycolic acid is derived from sugar cane or made synthetically and is the most common type of AHA. Others include malic acid derived from apples and mandelic acid derived from a certain type of almond.
Glycolic acid works in a number of ways, primarily through its exfoliation properties. Once applied, glycolic acid penetrates the upper layer of the skin, weakening the anchors that hold dead skin cells together. This allows the layer of dead skin cells to slough off, revealing the smoother and more evenly pigmented underlying skin. In addition to removing dead skin cells, glycolic acid helps to bind water to the skin to increase skin hydration leading to a healthy glow.
Beta Hydroxy Acids (BHAs) are another class of compounds commonly used in skin care products. The best-known BHA is salicylic acid. Most often, BHAs are used for people with acne-prone or oily skin types because of the excellent penetration into the pores, removal of blackheads and reduction of oil on the surface of the skin.
Proper use of AHAs and BHAs is based on an individual’s skin type. I find that most skin types (even those with rosacea or very sensitive skin), can benefit from some form of AHA. However, depending on sensitivity, perhaps only a once or twice weekly application of a cream formulated for sensitive skin will be tolerated.
People with more oily skin can use a glycolic toner or lotion easily every day without irritation. For skin types in between these two extremes, I recommend starting a glycolic acid containing product every other day and increase as the skin gets accustomed to the product. It is not desirable (nor necessary) for the products to cause irritation to deliver radiant skin. The goal should be gradual improvements in the appearance of the skin with no irritation. Daily use of a product with at least an SPF of 30 is very important when using either AHA- or BHA-containing products because they render the skin slightly more sun sensitive due to a thinned dead skin cell layer. But this is a small price to pay for skin that literally glows with health.