Hydroxyl image from Wikipedia

Alpha Hydroxy Acids & Beta Hydroxy Acids

As reported in What is salicylic acid?, salicylic acid is the beta hydroxy acid (BHA) used in many skin care products, and as shown in What is glycolic acid?, glycolic acid is an alpha-hydroxy acid (AHA) which is also used in numerous skin care products.

Salicylic Acid

Salicylic acid is the only beta hydroxy acid found in cosmetic products, so when we discuss BHAs, the term beta hydroxy acid is interchangeable with salicylic acid.

Glycolic Acid

While glycolic acid is is the smallest and best-known of the alpha-hydroxy acids, there are other AHAs which may be either naturally occurring or synthetic including lactic acid, citric acid, mandelic acid.

Glycolic acid image from Wikipedia

Both products assist in the removal of dead skin cell and both products reduce the appearance of fine lines and blemishes. Both can have a positive effect on acne and wrinkles. So, what is the difference between alpha and beta hydroxy acids, and how do you know which product to choose?

Salicylic acid image from Wikipedia

What is the Difference between Alpha & Beta Hydroxy Acids?

The chemical difference between the two products is subtle to a layperson. Both AHA and BHA are chemical compounds characterized by a carboxylic acid group and a hydroxyl group. The difference between AHAs and BHAs involves the location of the hydroxyl group in the compound. The result of this difference in the chemical compound is that alpha hydroxy acids are only soluble in water, and beta hydroxy acid is soluble in oil.

Alpha Hydroxy Acids

Since alpha hydroxy acids are water soluble and act on the upper layers of skin, AHAs remove old, dead cells and speed up the production of fresh skin cells, so they work better on sun-damaged, older, thicker skin.

Beta Hydroxy Acids

Beta hydroxy acid is able to penetrate into the oil-filled pores and break down the dead skin cells inside the pores, so salicylic acid works best on oily skin.

Which Product to Choose: AHA or BHA?

Alpha hydroxy acids are for good for treating dry, damaged skin, and beta hydroxy acids are better for treating acne on younger, oily skin.

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