For most, the first thing that likely comes to mind when thinking about vitamin C is either an image of citrus fruits or its ability to keep your immune system healthy. But this popular vitamin has several benefits for skin when applied topically, too.
So what exactly are they and why should you be using vitamin C on your skin? Below, answers to all your questions about vitamin C and how to include it in your skincare routine (spoiler alert: a good vitamin C serum is our favorite!).
First, what is vitamin C?
Also known as ascorbic acid, vitamin C is a water-soluble antioxidant that plays important roles in immune function and skin health due to its protective and free radical-fighting capabilities. Although it is crucial for these biological functions, “humans are not able to synthesize vitamin C in the body, so it has to be obtained through diet,” explains Good Housekeeping Institute Registered Dietitian Stefani Sassos, M.S., R.D.
There are unique skin benefits to getting your vitamin C through food or supplements or topically. “When taken orally, it can promote collagen growth and help accelerate the healing process of wounds”, says Registered Dietitian Amy Fischer, M.S., R.D., C.D.N. In other words, it helps to maintain overall skin health. Topical vitamin C is better at delivering the ingredient directly to skin, visibly improving the look of skinby brightening and firming while protecting from environmental stressors bombarding the barrier.
What are the forms of vitamin C in skincare?
When it comes to skin there are several forms of vitamin C, but its most biologically active form and the most studied in skincare is L-ascorbic acid. Its derivatives (such as magnesium ascorbyl phosphate and ascorbyl palmitate) are less active but more stable and can also be less irritating for those who have sensitivities to ascorbic acid.
What are the skin benefits of vitamin C?
“Vitamin C is a well-known antioxidant in skincare,” says Lian Mack, M.D., a dermatologist in New York City. In skin, this antioxidant has several functions including playing a role in the production of collagen, improving hyperpigmentation and neutralizing free radicals. Here are the primary benefits of vitamin C when applied topically to the skin:
✔️ It protects skin cells from environmental damage
Vitamin C's main function in skin is that of a powerful antioxidant, protecting from cellular damage caused by free radicals. “Free radicals are the molecules produced by the body when exposed to radiation from the sun, tobacco, smoke, X-rays or other sources,” Dr. Mack explains, and they are highly reactive. Vitamin C neutralizes these free radicals by donating electrons, preventing them from damaging skin.
Unlike sunscreens that absorb or reflect harmful UV rays from the sun to prevent sunburn, topical vitamin C offers protection through its role as an antioxidant. Since it doesn’t have the same mechanism of action as a sunscreen, vitamin C is not a sunscreen and should never replace your SPF. Rather, they complement each other and can be combined for optimal effects.
✔️ It brightens skin and reduces hyperpigmentation
The ingredient is also one of the gold standards for evening skin tone and boosting radiance. “Vitamin C is a well-known skin brightener, impeding melanin production and ultimately fading dark spots, resulting in a more even complexion,” Dr. Mack explains.
✔️ It firms skin and promotes collagen production
Our skin is made of collagen and elastin, which are proteins that give it structure and elasticity. As we age, the production of collagen decreases and our skin beings to look and feel less firm. “Daily application of vitamin C helps to maintain the integrity of the collagen that we have, prevents rapid breakdown and promotes collagen production,” Dr. Mack says.
✔️ It works with other antioxidants for enhanced UV protection
Vitamin C works synergistically with the antioxidants vitamin E and ferulic acid to reduce UV damage in skin. A study in the Journal of Investigative Dermatology showed that a combination of vitamin C, E and ferulic acid not only offered improved stability of vitamins C and E but also improved skin's UV protection.
What's the best way to use vitamin C on skin?
The ideal time to use a skincare product containing vitamin C, such as a serum or moisturizer, is in the morning. “Application is best during the day coupled with sunscreen,” Dr. Mack says. This way, “it will optimize the benefits of your sunscreen but also help prevent damage from free radicals," adds Roberta Del Campo, M.D. a dermatologist in North Miami, Florida.
Although best used in the A.M., vitamin C can also be applied at night if you are looking to decrease the appearance of discoloration, Dr. Del Campo says. Since every vitamin C product is uniquely formulated, always use your product as directed on packaging for optimal results.
What are the side effects of vitamin C?
“Topical vitamin C is well-tolerated by most, but in very rare instances some individuals may develop a hypersensitivity reaction,” Dr. Mack says. This can be particularly true for those with skin conditions like eczema or rosacea. Since vitamin C is formulated at an acidic pH to remain effective, it can potentially aggravate these already compromised skin barriers.
To prevent excessive skin irritation, avoid pairing vitamin C with retinol, which is known to cause redness and irritation, and exfoliating ingredients like alpha hydroxy acids. With serums and moisturizers, start slowly once a day at a lower concentration and increase to twice a day as tolerated.
And know that more isn't always better when it comes to active skincare ingredients like vitamin C. “Using too high of a percentage of vitamin C can be very irritating to the skin, leading to redness and dryness," Dr. Del Campo explains. She recommends sticking to formulas with a 10 to 20% concentration of vitamin C for efficacy without irritation.
What to look for when shopping for vitamin C skincare products
Vitamin C is highly effective in its pure form, ascorbic acid, but is a tricky ingredient to formulate with because it is very unstable and can degrade with exposure to oxygen, light, water and high pH. That means that while it is a hero ingredient, its beneficial properties are difficult to stabilize. Here are the most important factors to look for when shopping for vitamin C skincare products:
A dark container to protect from light damage
An airtight container to prevent degradation from oxygen
A low pH (about 3.5) to keep the ascorbic acid stable and help the vitamin C penetrate skin
Ingredients like vitamin E and ferulic acid that can improve stability of the formula and work synergistically for enhanced benefits
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