You’re Wasting Your Money on Vitamin C Unless You Know This One Thing

Of all the skincare ingredients I love (and there are many—niacinamide, peptides, retinoids, need I go on?), vitamin C might be the one I love the most. That’s for two reasons. The first is that it’s a true multitasker, and it has myriad benefits (but more on that in a minute). The second is that it’s made a big difference in the state of my skin. Over time, it’s made my skin look brighter and more even-toned.  That doesn’t mean I’ll use any old vitamin C product that comes my way. In fact, it’s quite the opposite. I’m very picky about the whole thing, and I only hold a few vitamin C products in high enough esteem to give them a spot on my bathroom counter. It’s not that I’m being finicky (although maybe I am), it’s that choosing the right one matters. Using it correctly matters, too. Ahead, see the one thing you need to know before using vitamin C. 

First, let’s talk about the benefits of vitamin C and how it functions in the skin. According to SkinSpirit lead aesthetician, Karen Fernandez, “Vitamin C is an antioxidant that helps reduce environmental damage.” 

In other words, it fights those pesky unpaired electrons that we call free radicals. If you didn’t know, free radicals come from all sorts of different things, including sun exposure, pollution, and even normal metabolic processes in the body. They can damage DNA and lead to signs of aging like fine lines and wrinkles. The antioxidant function of vitamin C prevents that from happening. “It surrounds the skin cells and deflects triggers that want to harm your skin,” Fernandez says. “I think of vitamin C as ‘your internal SPF’ designed to protect and embedded in your epidermal skin layer.”

The best part is that vitamin C does double duty. It’s an antioxidant, and it also functions as a skin brightener. Over time, vitamin C can brighten dullness and lighten dark spots and hyperpigmentation. In other words, it can give you a more even-toned complexion. 

And it works for all skin types, regardless of how dry or oily you are or what concern you’re trying to tackle. That goes for all antioxidants. “Antioxidants are good for all skin and skin types,” Fernandez says. “They prevent damage and also visibly brighten skin.” 

While vitamin C is unrivaled as a skin-brightening antioxidant, there is a catch (well, sometimes), and that’s that it’s notoriously unstable. If it breaks down (or oxidizes) before it hits your skin, it’ll be rendered ineffective. What’s more, is that the oxidized vitamin C could potentially cause irritation and blackheads. 

“That is the downside of vitamin C,” Fernandez says. “It can be unstable, which means it can be made ineffective by environmental factors (like too much light or heat). For most formulas, the color will darken and it will have an incorrect balance of actives and alcohol.” 

So, how do you make sure your vitamin C is stable? Fernandez says all you need to do is check the color and smell of the product. If the color is darker than it was when you bought it (for example, if it turned a dark brown color) or it smells a little funky, toss it. It’s not worth using anymore. The fact is that it’s already oxidized and you simply won’t be getting the benefits you once were. To avoid this from happening, Fernandez recommends making “sure to store in a temperate place with no direct sunlight or heat fluctuations.”

Fernandez recommends using vitamin C daily and in the morning under sunscreen. “It is designed to protect your skin and can do that all day,” She says. Just know antioxidants can benefit the skin both morning and night, which is why she also recommends incorporating an antioxidant serum into your nighttime routine. “Some antioxidants have reparative aspects and will regenerate the skin’s cells at night while you sleep,” she says. “This rebuilds and replenishes cells from the inside out, leaving skin refreshed in the morning and able to defend against the day’s aggressors.” 

The only time you shouldn’t use vitamin C is when your skin is sensitized from any in-office treatment. While Fernandez says there are formulas out there that are designed to help the healing process and can be good for post-treatment skin, the majority are not. “Unfortunately, most over-the-counter vitamin Cs are not medically formulated and will just irritate skin that is already sensitized.” 

Fernandez calls this her “absolute favorite” vitamin C serum. “It has both functions of protection and regeneration—best used AM and PM. This is my go-to for anyone with pigment issues. It is a broad spectrum antioxidant and is a 100% stable formula in an easy-to-use container.”

Fernandez calls this “a more straightforward vitamin C, but very stable and easy to use.” She says it’s great for sensitive and acne-prone skin specifically, and its light and creamy formula doesn’t dry out the skin or leave a residue. Also, “it’s medical-grade, meaning full efficacy with no fuss.”

“SkinCeuticals CE Ferulic is a classic and was our first exposure to high-quality vitamin C,” Fernandez says. “It is still a winner—some love the liquid formula (except when it spills), but it’s also more volatile in its stability and needs to be stored carefully.” 

This moisturizer is enriched with vitamins C and E, so it visibly brightens and smooths the skin. 

This serum has a light, creamy texture and contains both lipid and water-soluble forms of vitamin C, meaning it can penetrate deep into the skin. Even though it’s incredibly effective, it never irritates my dehydrated, redness-prone skin. 

This serum is so effective, the brand promises it will even work on stretch marks and scar tissue. It uses vitamin C, amino acids, vitamin B5, centella asiatica, and zinc sulfate to smooth the skin and encourage collagen production. 

With a unique oil-based formula, this vitamin C product is great for anyone who struggles with dryness.

With 15% vitamin C, this serum can improve brightness, firmness, discoloration, and dullness in one fell swoop. 

With vitamin C, retinol, niacinamide, and salicylic acid, this serum does a little bit of everything. 

One of my favorite French pharmacy brands, La Roche Posay, makes this 10% vitamin C serum. It also contains both hyaluronic and salicylic acids for extra benefits.

Up next, check out the best vitamin C creams (if you want to skip the serums)