What can you not mix with glycolic acid? AHAs and BHAs, such as glycolic, salicylic, and lactic acids should never be used with Vitamin C. Vitamin C is an acid, too, and is unstable, so the pH balance will be thrown off by layering these ingredients together and might as well be useless.
What can you not mix with niacinamide? Don’t Mix: Niacinamide and vitamin C. Although they’re both antioxidants, vitamin C is one ingredient that’s not compatible with niacinamide. “Both are very common antioxidants used in a variety of skincare products, but they should not be used one right after the other,” says Dr. Marchbein.
Can I use the ordinary glycolic acid toner with niacinamide? You can actually layer your glycolic acid and niacinamide together, at the same time of day—just 30 minutes apart. When layering products, start with the one that has the lowest pH first.
What works well with niacinamide? Niacinamide is uniquely compatible with any of the products in your skincare routine, including those that contain retinol, peptides, hyaluronic acid, AHAs, BHA, vitamin C, and all types of antioxidants.