Ask Me: What is the Difference Between Alpha and Beta Hydroxy Acids?

Have I mentioned how much I love reader mail? No? Well, it makes me happy. And I love questions the best. It makes me break out all my researching skills to come up with a reasonable answer. Here is this week's question:

Q: I read a lot about products that use alpha and/or beta hydroxy acids for my skin. What is the difference between the two and how are they beneficial?

A: Excellent question! The main difference between alpha hydroxy acids (AHA's) and beta hydroxy acids (BHA's) is their ability to dissolve lipids or oils. AHA's are only water soluable and cannot penetrate surface sebum or oil. BHA's are able to penetrate the sebum and are recommended for skin that is prone to breakouts. On the other hand, AHA's are perfect for skin that is sun-damaged without breakout problems.

The most common AHA's are glycolic and lactic acids derived from fruit and milk sugars. Other AHA's are citric and malic acid. They work mainly as exfoliants, removing dead skin cells and may or may not stimulate the skin's production of collagen and elastin. When purchasing a product with AHAs, look for a percentage of 5 to 8%. AHAs can increase sun sensitivity, so be sure to use a good sunscreen during treatment.

There is only one BHA, and that is salicylic acid, which is derived from asprin. BHA products work best with a concentration of 1 to 2%, and most acne treatment products use 2%, which seems to be the magic number for truly problematic skin. BHAs also work as exfoliants, but are able to penetrate through the sebum layer on the skin into the pore to remove buildup there, which is why many blackhead treatment products feature BHAs. Again, it's important to use sunscreen during treatment, as BHAs have been known to increase photosensitivity.

Photo by thebettymae on flickr