Alpha and beta hydroxy acids in cosmetics

Alpha hydoxy acids (AHA) and beta hydroxy acids (BHA) are compounds commonly used in skin care products. They are known to be chemical exfoliates, which can be used at different concentrations to give the desired effect. AHA's are usually found in facial peels, skin creams, and body scrubs. They are used to reduce signs of aging and improve the look of the skin. Citric acid, malic acid and glycolic acid are a few AHA's used in the cosmetic industry. BHA's besides having similar anti-aging benefits as AHA's have also been found to unclog and cleanse pores. Therefore salicylic acid, which is a BHA, is a common ingredient found in facial products for acne prone skin. 

In an AHA the hydroxy group (OH) is one carbon away from the 'acid' group (meaning the carboxylic acid group). In a BHA the two groups are two carbons apart. The main difference between AHA's and BHA's is their solubility. AHA's are water soluble, where as BHA's oil soluble. Because of their chemical structure AHA's are more polar and therefore water soluble. BHA's have lower polarity and are oil instead of watre soluble. This means that BHA's are able to penetrate into the pore which contains sebum and exfoliate the dead skin cells that are built up inside the pore. Because of the difference in properties BHA's seem to give better results on oily skin with whiteheads and blackheads. AHA's are a better choice for dry skin without a tendency to break out.