Everyone Is Obsessed with It, but What Does Vitamin C Do for Your Skin?

Vitamin C is like the Euphoria of the skincare world these days. You can’t escape it. Everywhere you look—from the aisles of Sephora to your TikTok feed—vitamin C is there. But let’s rewind the tape here for a second and figure out how it came to mass popularity when there are so many other ingredients out there.

According to Whitney Bowe, a board-certified dermatologist in New York, vitamin C serves three primary functions in your skincare routine:

“Vitamin C protects your skin from free radical damage, which we’re exposed to constantly through UV rays, infrared light and blue light from our screens. Basically, there’s no avoiding free radicals in modern day life. When we accumulate too much free radical damage, it increases oxidative stress in our skin, which can lead to premature aging and inflammatory responses like acne or eczema flare ups,” explains Bowe. “This is where vitamin C comes in. Its antioxidant properties help to neutralize any free radicals you come into contact with and further boosts the natural antioxidants that are already in your skin to prevent damage,” she adds.

“Vitamin C can prevent the overproduction of melanin in your skin, which manifests in several different ways depending on the triggers. Most commonly, it shows up as PIH or post inflammatory hyperpigmentation, which are marks leftover from acne, melasma, which is usually hormonal, or lentigos (aka sunspots) caused by overexposure to the sun.”

“Stabilized forms of vitamin C (more on that ahead) help boost collagen production in your skin, which in turn, can soften the appearance of fine lines and wrinkles.”

There are so many vitamin C products out there. How do I choose the best one?

If you’re wondering where in your skincare routine you should save vs. splurge, Dr. Bowe fully recommends spending a bit more on your vitamin C serum. “Vitamin C is actually very expensive to formulate in a way that keeps the concentration high enough to produce results and stabilized, so it doesn’t cause irritation and retains its potency after it’s opened,” she explains.

As for specific things to look out for in your serum, you’ll likely come across “L-ascorbic acid” in your shopping journey. Historically, this was considered to be the best form of vitamin C. “It certainly has the most data behind it and has been around the longest, which explains its prevalence. However, I describe L-ascorbic acid as a diva ingredient because it’s extremely challenging to formulate with. It’s very finicky in many ways. It tends to break down easily, it’s highly unstable, and it sits at a lower pH level, which can cause stinging or burning for people with sensitive skin. Newer science that’s beginning to emerge shows that there are vitamin C derivatives that are more stable, easier to formulate with and are better tolerated,” says Bowe. (Two rising stars she notes: tetrahexyldecyl ascorbate and ethyl ascorbic acid.)

And if that’s too much to remember (or attempt to sound out to a sales associate), Bowe says to look for language on the packaging that refers to its stability and lists other forms of vitamin C (like the two mentioned above) aside from just l-ascorbic acid.

How should I use vitamin C in my skincare routine?

Use your vitamin C serum every morning in this order: cleanse, pat your skin dry, apply your vitamin C, moisturizer and sunscreen. “I always tell my patients that consistency is key with your morning routine. You can cycle or switch off your active ingredients in your night routine (i.e., retinol one night, peptide the next) but keep your mornings consistent,” explains Bowe.

On that note, Bowe cautions against using retinol or another exfoliating product like glycolic or lactic acid in the morning. Ditto benzoyl peroxide, which is sometimes recommended for acne treatment in the daytime. “Benzoyl peroxide works by creating oxidative stress, which is the opposite of what vitamin C does. When you use the two at the same time it negates the effects of both,” she cautions.

3 vitamin C myths, debunked:

Falsehood #1: Vitamin C makes you more sensitive to sun. Actually, the exact opposite is true. “It works synergistically with your sunscreen to protect you from free radical damage, which can cause skin sensitivities in excess. Vitamin C boosts the effects of sunscreen,” the doctor tells us.

Falsehood #2: You don’t need to use vitamin C if you’re not going outside. Sorry, but the truth is that we’re actually exposed to some form of air pollution whether we’re indoors or outside. “Add to that the blue light from the constant screen time and any UV rays that come through the windows, and you’ll see why it’s a good idea to stick to your morning routine no matter your plans.”

Falsehood #3: For a DIY vitamin C treatment, you can rub lemon juice on your skin. Lemons have vitamin C in them, right? Technically yes, but that doesn’t mean it’s a good idea to rub the juice on your skin. “It’s not stabilized and can cause mild to severe irritation,“ cautions Bowe. “I’ve had patients come in with chemical burns from doing this,” she adds. (Psst, here are a few more skincare hacks that derms would prefer you not try at home.)

How long do I have to wait to see results—and what are realistic results I can expect from a vitamin C serum?

“That depends on what you want your vitamin C serum to do,” says Bowe. “As an antioxidant, it works immediately, and lasts for a couple of hours, which is why I recommend using it in the morning. For brightening and evening out your skin, that can take between six to 12 weeks, and if you’re relying on your vitamin C for collagen stimulation, it will take between three to six months to see results, so be patient.”