Do vitamin C serums really work? Which one should I buy? Dermatologists weigh in

Oct 28, 2024

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As a beauty editor who helps women over 40 find the most effective anti-aging products, I interview dozens of dermatologists and aestheticians each year. More and more, those experts recommend topical vitamin C to bolster healthier, younger-looking skin. In fact, because of the widespread popularity of vitamin C — and an influx of dozens of new creams and serums on the market — earlier this year, I spent four months testing vitamin C products and interviewing skin-care experts about how they work. All the doctors I spoke with considered a stable form of vitamin C a must-have for any quality skin-care routine. Here's why.

Vitamin C's skin-health benefits have been documented in dozens of clinical trials. Studies show that consistent, daily use of a stable form of vitamin C improves skin texture and evens skin tone on both the face and neck in as little as three months. In clinical trials, vitamin C serums have reduced hyperpigmentation from sun damage, lightened dark spots and diminished redness, particularly if the formula had a concentration of 10% to 20% vitamin C and contained stabilizing ingredients like ferulic acid and vitamin E.

According to dermatologists and skin-care experts, using a stabilized form of vitamin C is critical to maintaining bright, healthy, bouncy skin as we age. "A vitamin C serum is nonnegotiable. You need it twice a day," says facial plastic surgeon Dr. Kay Durairaj. "In the morning, it's an antioxidant to treat sun damage; in the evenings, it's going to help build collagen and skin repair."

"Vitamin C is an antioxidant," says cosmetic dermatologist Dr. Ava Shamban. "Antioxidants are substances that can protect, prevent or delay cellular damage by counteracting the free radicals and oxidative stress caused by environmental pollutants, UV rays, chemicals and other factors. Vitamin C is perhaps our most important antioxidant; it can boost brightening, improve hydration, reduce the appearance of wrinkles and hyperpigmentation, and fight inflammation."

First things first: Vitamin C is an unstable molecule that degrades rapidly when exposed to elements like sunlight or heat. For the product to be effective, you'll need to find packaging such as opaque plastic or dark-colored glass that will protect the product in transit and, later, storage. You also want to know that what's inside is fresh (more on this in my review below). Remember, vitamin C works best in tandem with ferulic acid and vitamin E, so study labels before buying. Last, a serum with less than a 10% concentration of vitamin C will not bring the skin-brightening, collagen-boosting benefits you want. On the flip side, more is not more: Over a 20% concentration will irritate most skin types. The sweet spot is somewhere in between.

Sephora

Ringing in at less than half the cost of the most famous vitamin C serum, Skinceuticals C E Ferulic, this Drunk Elephant option is a high-quality, highly effective alternative. I love it for all sorts of reasons, including the fact that after six weeks of twice-daily use, it lightened dark spots on my cheeks, noticeably tightened my skin and consistently gave my complexion a pretty, brighter glow. But what makes C-Firma superior to most competitors is the unique way it's packaged: The formula arrives in two parts — a liquid serum along with an accompanying vial of pristine vitamin C powder. You mix the two just before your first use, maximizing the stability of the vitamin C molecules and ensuring freshness. Once it's mixed, the product remains potent for three to six months, depending on how you store it (i.e., preferably in a cool, dark place, like a cabinet).

And there's more to love: C-Firma contains ferulic acid and vitamin E, which boost its efficacy. It comes in an easy-to-use bottle with a convertible pump. It has a pleasant, mild, citrusy scent. It's lightweight and absorbs quickly, though the texture may feel a bit sticky for some. Finally, it's potent — it may even sting your skin a bit.

Compared with Skinceuticals, this gains points for being both cruelty- and foul-odor-free (the former has a deeply unpleasant scent). While many beauty editors will tell you that Skinceuticals is the only vitamin C game in town, it's $182-$285 for just one ounce, making it inaccessible for most of us, at least for long-term use. (I don't care if it's made of gold, I'm not spending that kind of money on something to dab on my face — and I don't think you should have to either!)

At $79, C-Firma is not exactly a steal, but the formula (plus the effect on your skin) is top-notch. My first bottle lasted four months with twice-daily use, so a little goes a long way.

Amazon

There's an entire worldwide web of serum heads debating individual products' pH levels and the inferiority of C-derivatives like sodium ascorbyl phosphate over L-ascorbic acid. However, once you get deep into wonky skin-care Reddit, you find a consensus: For an affordable, high-quality vitamin C serum, the closest to Skinceuticals is this one by Timeless. It's lightweight, absorbs quickly, is less sticky than C-Firma and contains the right percentage of the main ingredient, combined with vitamin E and ferulic acid.

Timeless's vitamin C serum boasts more than 6,000 exuberant five-star reviews on Amazon, all repeating something along the lines of this one: "OMG! Someone finally did Vitamin C right, and they're not charging 100s of $$ per ounce!"

The reviews quoted above reflect the most recent versions at the time of publication.