Learning how to use vitamin C the right way is a worthy skin endeavor. The expert-approved ingredient is the gold standard for brightening up a dull complexion and erasing sun spots (especially as the years go on), and it’s a natural collagen booster. In short, getting familiar with the powerhouse antioxidant is essential for any robust skincare strategy.

“Vitamin C is perhaps the most potent topical antioxidant we have,” says dermatologist Joshua Zeichner, MD. “It neutralizes free radical damage and protects the skin against UV light and other environmental aggressors, as well as blocking abnormal production of pigmentation to even skin tone and fade dark spots.” And while it’s best known for brightening, it can also be instrumental in skin firming, adds Los Angeles facialist Kate Somerville. “I have used vitamin C in my clinic for years to help with elasticity and tighten the skin around the neck and décolletage,” she says.

Though it does come with a few side downsides (Michelle Henry, MD, a New York City-based board-certified dermatologist, says that it can be irritating for those with sensitive skin or if you happen to be using a strong percentage of it, and you might experience redness, stinging, or breakouts if you’re not careful), that shouldn’t deter you. It’s all about finding the best product for you and your skin. “Everyone can benefit from Vitamin C,” says Shereene Idriss, MD, a New York City-based board-certified dermatologist and founder of Dr. Idriss skincare. “It’s a staple in any skincare routine, no matter your age. You just need to find the right form for your skin type.”

Here, how best to utilize the hero ingredient for a brighter, smoother, and plumper complexion.

Choose the Right Concentration

Identifying the right concentration for your skin type is essential to how effective your topical vitamin C will be, says New York City dermatologist Dr. Patricia Wexler. “Begin with a low concentration of 10% and increase to 15% or 20% as tolerated,” she instructs. For oily or normal skin, L-ascorbic acid is the most potent form of vitamin C and can be the most beneficial, while for dry and sensitive skin, magnesium ascorbyl phosphate, a water-soluble vitamin C, is less irritating.

Pay Attention to pH

Absorption of a vitamin C is largely contingent on its pH level. If you have normal skin, look for one with a low pH of approximately 3.5 for optimal absorption. If you have sensitive skin, you should use a formula with a pH of 5 to 6. “This is the skin’s natural pH and will not be as irritating,” says Wexler.

Go With a Serum

Serums are the most common type of vitamin C product. They’re designed to deliver a high concentration of actives in simple, layerable form: they “keep that ingredient stable and enhance penetration through the outer skin layer,” says Zeichner. As far as complementary ingredients are concerned, Wexler believes vitamin C works best in combination with vitamin E, ferulic Acid, vitamin B, and hyaluronic acid. “Vitamin C and E are both antioxidants and support each other,” she explains, adding that ferulic acid is another antioxidant which boosts and stabilizes both vitamin C and vitamin E in fighting free radical damage and collagen production. That being said, sensitive skin types might benefit from mixing their serum into a moisturizer, or opting for a vitamin C-infused moisturizer for gentler delivery.

Start Slowly

Regardless of the sensitivity of your skin, a gradual testing of new ingredients is always advisable. “With any active, it’s important to start slowly when incorporating ingredients into your routine,” says Somerville. “I’ve seen some amazing results with clients who’ve added vitamin C into their regimen at three times a week and worked up to daily use.” To that end, don’t expect instant gratification. “It takes several weeks of continuous use to start to see improvement in skin tone,” says Zeichner, adding that because it’s a key ingredient for prevention, some of Vitamin Cs benefits will be imperceptible.

Store It Safely

Vitamin C serums come in two broad categories: Water-based and anhydrous (which means “without water”). The former is more unstable and light sensitive, and is typically held in opaque or amber-colored bottles for that reason, while the latter tends to be more stable, even in the presence of sunlight. No matter what kind you opt for, ensuring your vitamin C is stabilized and kept airtight in a dark, cool space is essential. “If the color becomes dark or cloudy it has already oxidized,” cautions Wexler, adding that the same is true if you detect a rancid odor. Packaging matters, too. According to board-certified dermatologist Dr. Whitney Bowe, traditional droppers can speed up oxidization and cause the antioxidant to break down, so opt for airless pumps when possible.

Layer It Under SPF

Unlike hydroxy acids or retinol, vitamin C does not make the skin more vulnerable to sunburn. The most potent forms of vitamin C itself, though, are vulnerable to light exposure, making broad-spectrum UVA/UVB coverage worn in conjunction with the ingredient a must. The good news is that, when layered underneath sunscreen with a minimum of SPF 30, vitamin C protects the skin even further. “Think of it as a safety net to help neutralize free radical damage that can occur from UV light penetration despite our best protection efforts with sunscreen,” says Zeichner.

Brighten Up Your Diet

While vitamin C is a topical powerhouse, it also works wonders within. “You can incorporate vitamin C into your diet to nourish your skin from the inside out,” says Bowe. “Citrus fruits (oranges, lemon, grapefruit) are a great source of vitamin C, but you can also reach for bell peppers and more.”

What step in your skincare routine do you apply vitamin C?

Dr. Idriss says that this will depend on the type of vitamin C product you’re using. If you’re using a vitamin C serum, she says that you’ll want to use it right after cleansing your face. If you’re using a vitamin C moisturizer, she says it can double as your hydrator and treatment step.