Everything You Need To Know About Vitamin C In Skincare

A firm favourite in the beauty industry, vitamin C is a skincare powerhouse backed by a ton of scientific research. The ingredient is frequently recommended by dermatologists, who swear by its brightening benefits and antioxidant properties.

Want to learn more about what vitamin C can do for you? We asked Dr. Marc DuPéré, a plastic surgeon and founder of Visage Clinic in Toronto, and Dr. Shannon Humphrey, a dermatologist at Humphrey & Beleznay Cosmetic Dermatology in Vancouver, to share everything you need to know about using vitamin C skincare.

What is vitamin C?

Vitamin C (also known as ascorbic acid) is a water-soluble vitamin that helps fight hyperpigmentation and provides antioxidant benefits for the skin when applied topically. It also has immune-boosting benefits when ingested.

"It's important to get adequate vitamin C in your diet, and vitamin C levels are correlated to eating fresh fruit and vegetables," says Humphrey. She suggests pairing dietary vitamin C with topical applications to yield the best results.

What are the skincare benefits of vitamin C?

Vitamin C is not just a one-trick pony—it has multiple skincare benefits when used properly. "Vitamin C protects the skin from UV damage and suppresses hyperpigmentation (goodbye, dark spots!). It also preserves the integrity of collagen and elastic fibres and even promotes synthesis of collagen," explains Humphrey.

Because it is such a powerful antioxidant, vitamin C helps minimize sun damage and inhibits melanogenesis, which is the process of pigment formation in the skin. "[It] brightens and evens out the complexion and strengthens the skin’s vascular wall to provide an anti-inflammatory effect," says DuPéré.

How do I pick the right formula for my skin?

For starters, both DuPéré and Humphrey say that using a vitamin C serum is the most effective way to make the most of the ingredient. "It provides better absorption and is easier application than other types of products," says DuPéré.

Choosing the right dose is also important. Different products contain different percentages of vitamin C—start with a stable 10 to 20 percent L-ascorbic acid (a form of vitamin C that's widely considered the purest and most powerful), mixed with vitamin E for better absorption, according to DuPéré.

Want something gentler? Look for products formulated with tetrahexyldecyl ascorbate, a stable form of Vitamin C that DuPéré recommends as it tends to be less irritating and is generally tolerated by all skin types. It layers well with sunscreen, too.

Other forms of vitamin C you might spot on packaging include magnesium ascorbyl phosphate and sodium ascorbyl phosphate, which are less potent than L-ascorbic acid and might be found in more affordable options or in those formulated to be more gentle.

When do I use vitamin C?

While some active ingredients can only be used at night, vitamin C can be used during the day. In fact, it's usually recommended for daytime use because of its free radical protection, something your skin generally needs more of during the day due to pollution and UV rays.

Humphrey says the best way to use it is to apply a few drops of vitamin C serum on freshly cleansed skin every morning, followed by moisturizer and broad-spectrum sunscreen.

"Because vitamin C has a reservoir effect, using it once a day is sufficient to have an impact on your skin for up to 24 hours," says Humphrey.

It can be paired with ingredients like hyaluronic acid and niacinamide, which you'll often find in vitamin C serums, and ceramides, which are great to prevent any irritation in sensitive skin.

Do I need to introduce it into my skincare routine slowly?

While some more potentially irritating skincare ingredients, like retinol, require a slow introduction to your skincare routine, vitamin C doesn't require quite as much caution. Though vitamin C isn't a common irritant for most skin types, DuPéré still advises using products infused with the ingredients just a few times a week to start with and working up to a daily routine.

If it feels a little spicy at first, it's completely normal. "Vitamin C can be used on all skin types but because the pH of the product is low. Sometimes it can cause a slight stinging sensation," says Humphrey. "Those with sensitive skin may feel that more than others, but all patients can benefit from adding a vitamin C into their regime."

I've read that vitamin C is unstable. What does that mean?

Vitamin C is water-soluble and breaks down when exposed to oxygen. It's really that simple.

This property makes products containing vitamin C tricky to formulate, and their potency more difficult to maintain once the bottle has been cracked open. To keep your products as effective as possible, Humphrey recommends storing any vitamin C skincare at room temperature and out of direct sunlight. Look for formulas that are packaged in dark glass containers or opaque packaging. This helps improve stability and reduce oxidation.

Fresh vitamin C works better. You'll want to keep track of how long your bottle has been open and note the expiry date. "There are formulations that will last just a month, and others that will keep up to three months," she says. "It's generally not a product that can stay on your shelf for six, nine or twelve months."

When shopping for skincare, does a more expensive vitamin C formula equal better results?

Not necessarily. But because vitamin C is unstable, brands have to spend more time and money on research to ensure that their products are shelf-stable and will be properly absorbed into the skin—and that cost is often passed along to consumers. "The formulations I've seen with reasonable scientific evidence behind them have a [slightly] price point," says Humphrey of these skin care products.

That said, a higher price point doesn't automatically mean it's better. "When looking at formulas, it's about evidence," says Humphrey. "Have clear scientific evidence that the product is stable so when you open it and put it on your skin, there's actually still vitamin C in it."

Skimming packaging won't get you far when it comes to finding a quality product. Seek out recommendations from experts and do your research. Look for brands that post before and after photos of their research and study results.

Remember, it can take two to four weeks of daily usage to see results. If your skin starts looking brighter, that's a sure sign your vitamin C is working.

Shop editor-approved vitamin C serums below.

SkinCeuticals CE Ferulic Serum, $208

There’s no vitamin C serum as beloved as this SkinCeuticals staple, and for good reason. From fine lines to laxity to dark spots, this powerhouse tackles it all with a 15 percent dose of L-ascorbic acid. The pure vitamin C is combined with vitamin E and ferulic acid to help absorption and boost its antioxidant properties.

CeraVe Skin Renewing Vitamin C Serum, $38

Made with a 10 percent concentration of pure vitamin C and the brand's signature skin-soothing ceramides, this formula is gentle enough for sensitive skin types to use daily. The cream texture layers well with other skincare products and leaves skin feeling soft and nourished.

Naturium Vitamin C Complex Serum, $34

Looking for a budget-friendly pick that delivers? This lightweight formula combines both pure L-ascorbic acid and sodium ascorbyl phosphate, as well as kakadu plum, a fruit that's rich in vitamin C.

La Roche-Posay Pure Vitamin C12 Serum, $70

Even the most sensitive skin types can benefit from a vitamin C serum. This longtime crowd-favourite has been reformulated with a higher dose of pure vitamin C and neurosensine, a soothing and skin-strengthening ingredient also found in the brand's Toleriane Dermallergo line designed for reactive and allergic skin.

Vichy Liftactiv 16% Pure Vitamin C Brightening Serum, $64

Recently reformulated with a 16 percent concentration of vitamin C, this pared-back fragrance-free serum (it contains just 11 ingredients!) strengthens skin while improving its tone. It also features hyaluronic acid and glycerin to hydrate, as well as carnosine, an ingredient that protects against oxidative stress and helps maintain collagen.

Tatcha The Brightening Serum, $120

This serum targets uneven skin tone, hyperpigmentation and loss of firmness in one luxe formula thanks to a time-release vitamin C, Japanese plum, ferulic acid and pro-glutathione, a powerful antioxidant that targets dark spots.