Can You Use Vitamin C With Benzoyl Peroxide?

Why this verdict

This advice is based on chemistry rather than a clinical trial. Benzoyl peroxide releases reactive oxygen species (free radicals) as it breaks down, which is part of how it kills acne bacteria. L-ascorbic acid, the pure form of vitamin C in most serums, is valued precisely because it gives up electrons easily, and that also makes it unstable. Put a strong oxidizer and an easily oxidized antioxidant together, and some of the vitamin C is likely to be used up.

We could not find a study that measured this on skin, so we cannot say how much vitamin C is lost. The closest evidence is indirect: benzoyl peroxide rapidly broke down tretinoin, another oxidation-sensitive ingredient, in a 1998 lab study. Given that, splitting them is a cheap precaution.

There is a second, practical reason. Vitamin C serums need a low pH (below about 3.5, according to a 2001 absorption study) and can sting, and benzoyl peroxide is drying. On acne-prone skin, using both in one sitting makes irritation more likely.

Vitamin C derivatives such as sodium ascorbyl phosphate are more stable than L-ascorbic acid. We do not have good data on how they behave next to benzoyl peroxide, so our checker does not flag them, but keeping them apart costs you nothing.