Can they be mixed? Depends

"If you layer salicylic acid or benzoyl peroxide with a retinol or AHA, that is risking irritation and skin barrier breakdown," says Gohara. She recommends using one in the morning and the others in the evening to avoid irritation. She also notes that "benzoyl peroxide formulations can inactivate some retinols," which makes separation more important. Of course, salicylic acids and benzoyl peroxide are often used in conjunction with each other — just be sure to use caution when it comes to retinol and AHA products.

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Can they be mixed? Yes, but do it right

Since retinol, AHAs, salicylic acid, etc. can all cause increased sun sensitivity, a good sunscreen is clutch. However, don't go adding it in willy-nilly. Products with SPF 30 and above actually don't mix well with most active ingredients. The key is to "layer the sunscreen OVER the product with active ingredients," explains Patel.

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