A Guide to the Skincare Ingredients You Should Never Mix

So, you’re finally starting to create a skincare routine—or maybe you’re revamping the one you’ve been following for years. Regardless, when choosing new skincare products, it’s imperative to know which ones will mix and layer well together.

Based on your skin type, it might be tricky to navigate this complex landscape. Here, L'OFFICIEL provides a straightforward guide on which skincare ingredients should never mix together to ensure your skincare routine is both effective yet gentle enough on your skin.

First up is the most obvious combination we all know don't mix: oil and water. Oil repels water, so if you try to layer a water-based product over an oil-based product, like a balm, a film will be left on your skin that will prevent the water from absorbing. If you must use these two products in your routine, layer the oily product over the water-based one. But overall, stick to using water-based products and serums together, as these skincare products can sometimes not mix well together.

AHAs (Alpha Hydroxy Acids) and BHAs (Beta Hydroxy Acids), 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.

AHAs and BHAs are powerful exfoliating agents that work to remove dead skin cells, unclog pores, and promote skin renewal. Vitamin C, on the other hand, is a potent antioxidant known for its brightening and anti-aging properties.

While both AHAs/BHAs and Vitamin C offer significant benefits for the skin individually, these skincare products should generally not be mixed or used together because they can potentially destabilize each other.

When mixed, AHAs/BHAs and Vitamin C may alter each other's pH levels, reducing their efficacy and potentially causing irritation or sensitivity on the skin. This can lead to adverse reactions such as redness, inflammation, or even chemical burns in severe cases.

To maximize the benefits of both AHAs/BHAs and Vitamin C without risking irritation or diminishing their effectiveness, it's best to use them at different times of the day or on alternating days. For example, you could incorporate AHAs/BHAs into your nighttime skincare routine and Vitamin C into your morning routine. Alternatively, you could use products containing AHAs/BHAs one day and products containing Vitamin C on alternate days to ensure compatibility and optimal results while minimizing the risk of adverse reactions. Whatever you do, these are skincare ingredients that should not be mixed or layered in one routine.

Niacinamide is found with Vitamin C in some multi-ingredient serums as antioxidants, but it’s never a good idea to layer them together. Both ingredients are helpful for improving acne, but used together, they can actually trigger breakouts and their helpful properties can be diminished. If you have to use them together, apply them at least 10 minutes apart.

Retinol combined with these acids is a literal recipe for disaster, leaving your skin dry and irritated, since the main job of AHAs and BHAs is to exfoliate, which retinol already effectively does. It’s better to mix AHAs and BHAs with moisturizing ingredients and SPF.

Niacinamide used with AHAs and BHAs together have no effect and can actually cause redness. Because niacinamide has a pH of around 5-7, it can actually raise the lower pH of the acids, which is around 3-4, and cancel out its properties. Used separately, both ingredients can help skin texture, acne, and signs of aging, so we encourage you to still use them.

These two ingredients are probably never a good idea to use together because they both remove dead skin cells—using them both could cause a lot of irritation and ruin your skin barrier. Use one, and follow up with a hydrating product.

Sunscreen should be worn every single day (and reapplied every two hours!) but should never mix with makeup. When wearing both, layer on the sunscreen separately from the makeup and wait before applying other products so they have properly absorbed.