AHA? BHA? Chemical exfoliation? If you’re new to skincare or trying to build your routine, these terms can be a little confusing and borderline frightening. Acids and chemicals aren’t traditionally things you want to put on your face, but when it comes to exfoliants you should make an exception.
AHA (also known as alpha hydroxy acid) is a non-abrasive, leave-on exfoliator that is traditionally more effective and gentle than traditional scrubs. Sun damage and overly dry or oily skin can hinder your body’s ability to properly shed dead skin cells. These obstructions can cause skin concerns like dullness, clogged pores, milia, texture, and breakouts. Using an exfoliant can help your skin clear out the dead cells to make room for the new, healthy ones. Chemical exfoliants help to prevent breakouts and premature aging and reduce the appearance of pores.
But that is just the beginning. There are a lot of different types of AHAs and knowing when to use them is half the battle. So I put together this handy beginner’s guide to get you started. It’s back to school season so consider this Chemical Exfoliants 101.
What is the Difference Between Glycolic and Lactic Acid?
Glycolic acid is the most common of all the alpha-hydroxy acids and works by exfoliating the top layer of the skin. Glycolic acid peels smooth the skin, quicken the rate of cell turnover (which is reduced by up to 7% every ten years), decrease small wrinkles, and increase the fibroblast proliferation of collagen. Glycolic acid is also the smallest of the alpha-hydroxy acids which gives it the ability to penetrate deeper into the skin.
Lactic acid is another very popular AHA. It is extracted from milk but is usually found in synthetic form in most cosmetics. Lactic acid is great for wrinkle-reducing, wrinkle-refining, skin smoothing, and hydrating the skin. It also packs a powerful anti-aging punch. Unlike glycolic acid, lactic acid won’t temporarily thin the skin or make it significantly more sensitive to UV damage. It’s definitely superior for dry or sensitive skin types.
What About Mandelic Acid? Citric Acid? Or Tartaric Acid?
Glycolic and lactic acid are by far the most popular forms of AHAs but they aren’t the only ones. Mandelic, citric, and tartaric acid are starting to make a name for themselves in the chemical exfoliant game! Think of these as your JV squad.
Mandelic acid is an AHA that is derived from almonds. When applied to the skin in fairly high concentrations, mandelic acid has been shown to be a potent antioxidant in the skin (Tetrahedron). A review in Clinics in Dermatology further found that mandelic acid takes down skin roughness and fine lines.
Tartaric acid is an AHA from fermented grapes. It stabilizes the pH of formulations, instead of using EDTA or another buffer. You won’t get the same effects from 10% tartaric acid as, say, 10% glycolic acid, but you will get greater effects from 10% glycolic acid + any additional amount of tartaric acid than with 10% glycolic acid alone.
Citric acid is like the training bra of AHAs: It doesn’t really do a lot, but it is made for people who don’t need the support older girls do. Like tartaric acid, citric acid used to be chiefly used to keep the pH range of skincare products in check, but it is also a mild chelator, meaning that it can prevent small amounts of impurities from entering your skin. You probably shouldn’t use it alone as a chemical exfoliant but it does add a nice exfoliating boost when used with other AHAs.
How to Use Chemical Exfoliants
Okay, so you’ve chosen the AHA you want to incorporate into your routine, now what? After cleansing your skin, dispense a small amount of product into your hand or on a cotton round (I prefer using my hands but your mileage may vary). Apply it to your bare skin and let it soak in. I like to wait 5 minutes before continuing with my other treatments and moisturizer. When introducing chemical exfoliants into your routine, go slow! Start with using them once a week and go from there. Because AHAs make your skin more photosensitive, be sure you’re wearing an SPF every single day (even if you opt-out of using chemical exfoliants, you should still wear an SPF every day!).
Be sure you skip retinol use on the days you are using AHAs! Using retinoids and an AHA typically diminishes the effectiveness of both ingredients. Retinol esterification (activation) occurs optimally at a pH of 5.5 or higher. AHAs generally work best at a pH of 4.5 or lower. Some brands (like SkinBetter’s AlphaRet) have managed to make this combination work through a proprietary formulation combining AHAs with ethyl lactyl retinoate, which is a retinol ester that is more concentrated than retinol. Those retinol esters can be ten times more concentrated than retinol, so even if AHAs put them in a pH range where they’re not converted to their active form optimally, you’re still getting a decent amount.
Those are the basics of chemical exfoliants! Choose your favorite form, integrate it slowly into your routine, wear an SPF during the day, and don’t use them the same nights that you are using your retinol!