“We don’t make vitamin C. It’s just us and the fruit bat that don’t make our own vitamin C—we’re the outliers,” says chemist and skin-care guru Marie Veronique, who has a highly-coveted eponymous skin-care line. “But we do know that vitamin C is very important for the skin.” That’s why there’s been an influx of vitamin C serums, moisturizers, and cleansers onto beauty shelves.
This is a good thing, of course. Vitamin C is a beauty-boosting antioxidant that’s known for stimulating your skin’s collagen production, brightening dark spots, and repairing free radical damage. But skin-care specialist Kristina Holey, who works with Veronique, started noticing more and more clients with bad skin reactions from layering on the serums. “With this obvious rise of vitamin C products on the market, there was a direct correlation to these [irritation] responses to vitamin C,” says Holey. This led the skin-care duo to investigate what was up.
At a basic chemistry level, your skin’s acid mantle sits at a pH of around 4.5 to a 5. And vitamin C is a potent acid, notes Veronique, so in order for it to best penetrate your skin, “it has to be at a pH level of about three (or more acidic),” she says. It sounds like a scary experiment to be slathering acids on skin but actually most active ingredients are formulated at a low pH, says Joshua Zeichner, MD, a board-certified dermatologist, of ingredients such as L-ascorbic acid, retinoic acid, and hyaluronic acid. “This may cause some skin irritation, redness, and dryness,” according to him.
Aside from the naturally acidic makeup of vitamin C, when oxidation—the process when vitamin C interacts with the air around it and renders it useless—happens, sensitization and irritation can also happen. While this often occurs in old formulas within a bottle, vitamin C can also oxidize on your skin when it comes into contact with oxygen. This creates hydronium ions, according to Veronique, which can lead to skin sensitivity.
“You can only put acids on your skin so many times before you see something happens… and vitamin C is a strong acid.” —Marie Veronique
“It’s tricky when you really mess with your skin’s pH levels repeatedly,” says Veronique. “A lot of the barrier function compromises come from not paying attention to the pH balance and the microbiome. You can only put acids on your skin so many times before you see something happens, and vitamin C is a strong acid.” That’s why Holey and Veronique concocted their new C-Therapy Serum ($90), which uses new, more stable and gentle vitamin C derivatives for symptomatic skin.
“Some of the newer vitamin C esters are more stable than pure ascorbic acid, and can be formulated with a higher pH with less potential skin irritation,” says Dr. Zeichner. Not that he or Veronique are saying that L ascorbic acid—aka a form of vitamin C—is bad for your skin, you’ve just got to stick with the right formulations and avoid going overboard with using it.
“Too much vitamin C can brighten the skin, which seems like a good thing, but over time it can sensitize you to L-ascorbic and do things you didn’t mean to do to your skin,” says Holey. So watch out for inflammatory responses like pustules or dermatitis or extra redness or breakouts when using vitamin C, and stick with these more gentle formulations in the meantime.
New-to-the-United States Bynacht is bringing their potent vitamin C serum to your nighttime regimen. Formulated with a stable form of vitamin C surrounded by soothing hyaluronic acid and vitamin E, this serum is meant to be used as your skin repairs and rejuvenates itself.
Veronique and Holey formulated this serum specifically for sensitive and breakout-prone skin types. It uses two stable derivatives of vitamin C—tetrahexyldecyl ascorbate and magnesium ascorbyl phosphate—so that you get the same brightening and antioxidant effects of vitamin C minus any irritation, plus it has glutathione for healthier overall skin barrier function.
Yet another more stable and sensitive skin-friendly vitamin C serum that uses tetrahexyldecyl ascorbate as the antioxidant. And the brand’s backed by dermatologists for a super-smart formulation that also gives your skin bakuchiol, vitamin B5, and vitamin E in one product.
The Ordinary’s skin hydrator lets magnesium ascorbyl phosphate be the star of the show, moisturizing and brightening your complexion while fending off free radicals with the all-star antioxidant.
This gentle, soothing serum absorbs quickly for brighter, more even skin—it uses vitamin C derivative tetrahexyldecyl ascorbate along with other fruit-based antioxidants and algae for moisture and a nourished complexion.
And you can learn more about vitamin C in our episode of Dear Derm, below:
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