9 Things You Need to Know Before Using a Vitamin C Serum

By Sarah Jacoby
January 2020

Between brightening dark spots and helping to protect against UV damage, there’s a lot vitamin C can do for your skin. But the type of vitamin C serum you select, as well as how you use and store it, can significantly affect how much you actually get out of it.

“Vitamin C is a potent antioxidant that brightens dark spots, smooths fine lines, and, importantly, scavenges free radicals from the environment, pollution, and UV radiation,” Sara Hogan, M.D., dermatologist at UCLA Medical Center, Santa Monica, tells SELF. Over time, those free radicals can damage the skin, leading to premature signs of aging, and increase your risk for skin cancer. So protecting against UV damage with an antioxidant—and, of course, daily SPF—is important.

However, not all vitamin C products are created equal—and they can be irritating and finicky to use in some cases, Angela Lamb, M.D., director of Westside Mount Sinai Dermatology Faculty Practice, tells SELF. It’s important to read the label on the product and know what you’re really getting (which isn’t always an easy feat when it comes to over-the-counter products), especially if you have sensitive skin.

So, before you start going down the path of finding a vitamin C product for your face, peep these expert tips to get the most out of your vitamin C serum.

1. Use vitamin C serums in the morning.

There’s certainly no law against using vitamin C products in the evening, but you may get the most benefit from using them in the morning. “In general vitamin C products should be applied in the morning before heading out for the day, when UV radiation is at its highest,” Dr. Hogan says.

But vitamin C becomes less effective when exposed to light, so it’s important to give it time to absorb into your skin before going outside, SELF explained previously. You don’t need to wait a specific amount of time—as long as it’s absorbed, you’re good to go.

2. Use your vitamin C products at the right point in your skin-care routine.

The right moment to use your product depends on what kind of product it is, Dr. Hogan explains. For serums, you want to apply your vitamin C product to freshly cleansed skin, but before you moisturize. But antioxidant-containing moisturizers are also becoming more common, Dr. Lamb says, and you’d want to use those at the end of your routine.

3. Use the right concentration vitamin C for your skin type and concerns.

Different products may contain a wide variety of concentrations of vitamin C. In general, they range from below 5% all the way up to 30%, Dr. Hogan says, and this ingredient can have different effects at those concentrations.

Those with dry or sensitive skin probably want to stick with lower concentrations, around 5%, which are less likely to be irritating. But those with more oily skin or with more extensive pigmentation issues to tackle can handle higher concentrations. However, as SELF explained previously, the effects begin to plateau after 20%, so there’s usually no need to go higher than that.

4. Don’t use vitamin C with certain other ingredients.

Vitamin C is generally pretty safe and well tolerated, but if you have sensitive skin, it might sting a little bit—especially if you use it in the same part of your routine as exfoliating scrubs or acids.

The one ingredient you should steer clear of when using vitamin C is benzoyl peroxide, which can oxidize the vitamin C and, therefore, make it less potent, Dr. Hogan says. You can still use your benzoyl peroxide products, just not in the same part of your routine as the vitamin C. Try using vitamin C in the morning and benzoyl peroxide in the evenings, or use them on different days.

5. You can use vitamin C with retinol, but be cautious.

In the past it was thought that you should avoid using vitamin C products with retinoids at all costs. And that is still sort of true. They work best in different skin environments, so using them at the same time may make both less effective. And because they can have similar effects on the skin, experts do still advise against using these two ingredients together, Dr. Hogan says.