Both vitamins C and E come with their own impressive résumés: The two are beloved for evening skin tone, supporting skin repair, and supporting collagen production.* And when you pair them together—the benefits abound. 

“Certain antioxidants are synergistic,” says board-certified dermatologist Julia T. Hunter, M.D., founder of Wholistic Dermatology in Beverly Hills about the ingredient. “They strengthen one another, regenerate one another, and last longer in the body, so they’re more available in the skin.”

And vitamins C and E are famously synergistic. One study even found that vitamin E (and ferulic acid) increase vitamin C’s effectiveness1 eightfold; on the other hand, vitamin C regenerates vitamin E after the latter scavenges free radicals, further reducing oxidative stress2 to cell membranes.* All of this is a very science-y way of saying: Vitamins C and E have each other’s backs.

You’ll often find that many topical vitamin C serums will loop vitamin E into the formula, considering how well the two perform together. “When paired, vitamins C and E provide a powerful antioxidant combination,” dual board-certified dermatologist Brendan Camp, M.D., says in our vitamin E explainer. Plus, “Vitamin E helps stabilize vitamin C and keeps it from degrading quickly.” Vitamin C, as you may know, is a very finicky and unstable topical—so anything that helps extend its shelf life is worth noting.