What Skincare Ingredients Should You Never Mix With AHAs?

Before you decide to bring any new item into your skincare regimen, it's important to know how it might interact with other products you already use or medications or supplements you're taking. This is especially true when it comes to products that contain AHAs, also known as alpha hydroxy acids, a category that covers different acids. 

These AHAs, for short, are found in all sorts of different beauty products, per the U.S. Food and Drug Administration (FDA), but their primary purpose, as the FDA notes, is to cause some level of skin exfoliation. Healthline cites additional benefits of AHAs, including skin-brightening and wrinkle-reducing effects that are likely to stand out to consumers.

Like other ingredients, however, you'll want to keep an eye out for AHAs in the products you use since Everyday Health writes that there are some ingredients that should not be mixed with these acids for health reasons or otherwise.

There are a lot of combinations of skincare ingredients that shouldn't be mixed with alpha hydroxy acids (AHAs). Per Everyday Health, some of the big ones to avoid are retinol or other retinoids unless a specific product has been approved to be safe when blended with these acids. This, writes Everyday Health, is because the two ingredients used in combination could lead to irritation.

On the subject of combining retinol and AHAs, dermatologist Dr. Shari Marchbein took a stronger stance on InStyle, saying, "I strongly caution those also using retinoids for acne or anti-aging as the combination with various acids may cause excessive skin sensitivity, irritation, and redness. In fact, AHA and BHA should not typically be used together with retinoids on the same day."

L'Officiel also cautions against the use of vitamin C with AHAs since vitamin C is also acidic. According to the same piece, niacinamide and AHAs also should not be used together. (Skincare.com has more information on how both niacinamide and AHAs can be used safely.)

While there are a lot of products to avoid using in combination with alpha hydroxy acids, there are some that experts recommend blending with AHAs. Dr. Marchbein explained to InStyle that one such mix is to use an AHA and a moisturizer. The board-certified dermatologist said, "Moisturizing after applying AHA and BHA is extremely important so as to limit irritation. Look for ceramides, petrolatum, hyaluronic acid, and glycerin to hydrate and soothe skin."

In an NBC News Select piece discussing experts' views on AHAs, dermatologist Jessie Cheung, MD, favored lactic acid as an AHA and actually suggested the use of AHAs and vitamin C in combination, citing the pH levels of both AHAs and vitamin C — despite the previously mentioned advice to the contrary. If you're concerned about what may or may not work for your skin in relation to anything that you use or are prescribed, be sure to check with a doctor.