You’ve probably heard about vitamin C serum, even if you’re simply a casual user of skin care products. If you want to know what vitamin C does for your skin, though, you’ll have to read on. To sum up: Vitamin C, a so-called “powerful antioxidant,” has been shown to lighten age spots, diminish the appearance of fine wrinkles, and protect the skin from environmental free radicals.

There is a reason vitamin C serums have gained such a stellar reputation: they perform admirably. Vitamin C (and the skin-care products that incorporate it) is often advised as a treatment for a wide variety of common complexion issues, including but not limited to uneven tone, rough texture, fine wrinkles, acne scars, and general dullness. It’s one among the most sought-after components of modern skin care, as seen by its popularity in Allure magazine’s annual Readers’ Choice Awards poll. But how does it actually function on the skin? Is it the same powerful antioxidant that helps you feel better after drinking orange juice when you have a cold?

What is vitamin C?

Vitamin C, says dermatologist Patricia Wexler, M.D., is “a strong antioxidant that can neutralize free radicals” in the skin. Vitamin C’s anti-oxidant characteristics make it useful for the skin’s natural regeneration process, which in turn speeds up the healing of damaged skin cells.

How Vitamin C help the skin?

Vitamin C’s antioxidant properties are only one of its skin-saving properties. Additionally, it has many other skin-healing characteristics that guarantee its continued presence in your medicine chest. First, the high acidity of vitamin C applied topically “triggers the skin to heal itself by speeding the formation of collagen and elastin,” says New York City dermatologist Howard Sobel, M.D. Keep in mind that collagen and elastin are two of the skin’s natural protein fibers that work together to maintain a smooth, elastic appearance. Applying vitamin C topically can therefore aid in preventing the skin from aging prematurely by stimulating collagen formation.

Who shouldn’t take Vitamin C supplements?

Children should not take vitamin C because of a lack of research on the subject in humans. Before buying a vitamin C supplement, always check the label for the full list of ingredients. Consider a patch test or talk to your doctor before using if you have sensitivity or an allergy to any of the substances. If your skin is prone to breakouts or produces excess oil, look for a product that addresses both issues.

How can you add vitamin C into your current skin care regimen?

“The key is not the vehicle that vitamin C arrives in, but the form of vitamin C that is being applied,” says Kristina Goldenberg, M.D., of Goldenberg Dermatology in New York City. Look for ascorbic acid (or L-ascorbic acid), the most stable and effective form of vitamin C in skin care.

If you have acne, is vitamin C a good idea?

There are several caveats to adding a vitamin C serum to the routines of acne sufferers, but doing so may be beneficial. According to a 2013 review published in the Indian Journal of Dermatology, Venereology, and Leprology, topical vitamin C can reduce acne lesions in as many as 77% of patients.

Because of its ability to increase collagen production and brighten the skin, it is also useful for reducing the appearance of acne scars. (However, if you already have acne, you should avoid using any vitamin C formulations that are oily or pore-clogging, like as thick or rich creams.)