6 Best Vitamin C Serums to Brighten and Firm Skin

Vitamin C is an antioxidant that the body doesn’t make on its own; as an antioxidant, it defends skin against free radicals (created by exposure to UV radiation and pollution) that can otherwise wreak havoc in your skin cells. “Think of vitamin C as a bodyguard for your skin, helping prevent it from cellular damage and signs of aging by neutralizing these free radicals and protecting against oxidative stress,” says Dr. Rastogi.

It’s also a tyrosinase inhibitor—meaning it inhibits tyrosinase, an enzyme that’s important in the pigment-formation process. For that reason, “vitamin C can help reduce excess pigment and improve uneven skin tone,” says Dr. Rastogi. And on top of that, it also supports collagen production to improve wrinkles. “This combination of antioxidant, brightening, and collagen-supporting benefits makes vitamin C such a versatile skincare ingredient,” she says.

There are a few different forms of vitamin C—and there are some nuances between them. Here’s a rundown:

• L-ascorbic acid: This is the pure form of vitamin C, and it has the most research behind it. “However, it is also relatively unstable, oxidizes easily, and can be irritating, particularly at higher concentrations,” says Dr. Rastogi.
• Tetrahexyldecyl ascorbate (THD ascorbate): This is an oil-soluble form of vitamin C, which “is not only more stable, but it can penetrate the skin barrier more effectively, and target deeper layers of the skin,” says Dr. Nazarian. Unlike L-ascorbic, it’s not as irritating and better tolerated by sensitive skin.
• Sodium ascorbate phosphate: This form is water-soluble, so it doesn’t penetrate as well as THD ascorbate, but “it has higher stability than L-ascorbic and is a good choice for really sensitive skin,” says Dr. Nazarian. “The reason this one is popular is because it’s known to have some antimicrobial effect which targets the bacteria that causes acne.”
• Ascorbyl glucoside: This version of vitamin C is paired with glucose. “This combination with a sugar molecule causes a more sustained release of vitamin C and extends its effect over a longer period of time—it also happens to be cosmetically elegant,” says Dr. Nazarian, who says it’s a good option for people with sensitive skin.
• Magnesium ascorbyl phosphate: This is another water-soluble derivative that’s also more stable and tends to be gentler than l-ascorbic acid, according to Dr. Rastogi.

Vitamin C’s primary perk is that it’s a powerful multitasker, allowing it to benefit skin in multiple ways. “It’s great at neutralizing free radical and oxidative damage from the environment—one of the main pathways that causes skin aging and skin cancer,” says Dr. Nazarian. “It supports deeper tissue underneath our skin that boosts production of collagen fibers and proteins, and it also improves pigmentary issues for people who are prone to hyperpigmentation.” All told, it can tackle two of the biggest signs of aging—wrinkles and dark spots—in one fell swoop.

First, consider concentration. “For L-ascorbic acid, I generally recommend looking for a concentration in the 10% to 20% range,” says Dr. Rastogi. Higher is not necessarily better, although it depends on what you’re using. With L-ascorbic acid, concentrations over 20% can increase your risk of irritation without making a big difference in your results. However, “higher concentrations of THD ascorbate or sodium ascorbate phosphate are fine and often well tolerated,” Dr. Nazarian says.

Then, take other ingredients into consideration. “I also like formulas that combine vitamin C with antioxidants such as vitamin E and ferulic acid, which can help improve the stability and antioxidant performance of the formula,” she says.

And finally, look at the packaging. Since vitamin C can be unstable—meaning it can oxidize easily—“I prefer vitamin C products, and frankly all my antioxidants, to be an airless pump or in a tinted bottle to prevent oxidation and exposure to light or air,” says Dr. Nazarian.

It depends on what you’re looking for—if you can handle l-ascorbic acid, that’s great. If your skin is sensitive, THD ascorbate might be a safer bet. “The trade-off with vitamin C derivatives is that while they offer advantages in terms of stability and tolerability, they have less clinical data behind them than L-ascorbic acid,” says Dr. Rastogi. “Ultimately, the best form depends on an individual’s skin sensitivity and the overall formulation.”

Apply your vitamin C serum right after cleansing and before your moisturizer. “I particularly like vitamin C in the morning because of its antioxidant properties,” says Dr. Rastogi. “During the day, our skin is exposed to environmental stressors such as UV radiation and pollution, which generate free radicals. Vitamin C helps neutralize some of this oxidative stress, making it a great complement to sunscreen.”

Anyone can use vitamin C—and should, especially for those concerned with signs of aging. “Its antioxidant properties protect against premature aging by neutralizing unstable molecules that damage our tissue and destroy collagen,” says Dr. Nazarian. “I refer to it as my ‘invisible shield’ against the outside world and won’t leave the house without it on.”

Some forms of vitamin C need to be housed in a low-pH formula (meaning it’s acidic)—like L-ascorbic acid—can often cause irritation for sensitive skin types. “Other forms of vitamin C remain stable at a more neutral pH, and are naturally less irritating, with some even being deeply hydrating and gentle,” says Dr. Nazarian, who points to THD ascorbate, ascorbyl glucoside, and sodium ascorbate phosphate as good options.

Yes, packaging can make a big difference. “Since vitamin C is prone to degradation from light and air, packaging in opaque, airtight containers is necessary to minimize exposure to the environment,” says Dr. Rastogi.

When we test and review a product, we take a holistic approach to deliver well-rounded product recommendations. First, we lean on Vogue‘s vast network of experts—from board-certified dermatologists to celebrity estheticians—to gain professional acumen on the industry’s standout products, ones these specialists would actually use on their clients. We pair their expertise with our editorial best practices to curate the thoughtful edits you read on our site.

As it relates to vitamin C serums, we selected the best based on the following characteristics: ingredients, type of vitamin C, concentration texture, packaging, finish, and the skin-care concerns they address. To do this, we paired our own personal tests of each formula with expert guidance and reviewer insights to determine which we would recommend to you. Read more about our testing methodology here.

• Rachel Nazarian, MD, a board-certified dermatologist in New York, NY
• Supriya Rastogi, MD, a board-certified dermatologist in New York, NY
• Melanie Palm, MD, a board-certified dermatologist in Solana Beach, CA
• Shereene Idriss, MD, a board-certified dermatologist in New York, NY
• Y. Claire Chang, MD, a board-certified dermatologist in New York, NY