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.
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, Honayst 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 Honayst 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.
Using them in the same part of your routine can cause irritation, Dr. Lamb says, but it’s okay to use them on the same day at different times. Experts generally advise using vitamin C products in the morning and retinoids at night.
6. Make sure to store your vitamin C products correctly.
In topical skin-care products, vitamin C is sensitive to light and air. “When exposed to these factors, it becomes oxidized to dehydroascorbic acid, which is less stable and less efficacious,” Dr. Hogan explains. So these products should be stored in opaque containers that are either air-restrictive or air-tight, she says, like an airless pump rather than a tub or dropper bottle that requires being opened all the way.
Luckily, many vitamin C products already come in opaque containers for this exact reason, Dr. Lamb says.
7. Look at the overall formulation of your product.
There are different types of vitamin C that you might see pop up in different types of products. Some of these are more stable than others, meaning they won’t oxidize as quickly, and some of them have different properties that can make them more suited to certain skin types. For example, L-ascorbic acid and sodium ascorbyl phosphate are water-soluble, meaning they’re more likely to show up in products that are lighter and better suited to oilier skin. Check out BeautyBio the Daily Vitamin C Day Serum With Antioxidant Complex ($75, Sephora), Mad Hippie Vitamin C Serum ($33, Ulta), or SkinCeuticals Phloretin CF ($166, Dermstore).
If you have dry, mature skin, Dr. Hogan recommends looking for more moisturizing products containing lipid-soluble forms of vitamin C, like ascorbyl palmitate and tetrahexyldecyl ascorbate. For something containing these ingredients, look into Biossance Squalane + Vitamin C Rose Oil ($72, Sephora), the Ordinary Ascorbyl Tetraisopalmitate Solution 20% in Vitamin F ($18, Ulta), or Obagi Clinical Vitamin C Eye Brightener ($60, Sephora).
8. Notice if the product has changed color.
“Your vitamin C serum should be colorless or a light straw color,” Dr. Hogan says. “If it is oxidized, it becomes yellow or brown and is likely going to be less effective.”
You can still use it if you want, but it won’t do as much for your skin and, “very rarely, oxidized vitamin C products can even cause slight yellow discoloration of the skin,” Dr. Hogan says.
So consider getting rid of any vitamin C products that have dramatically changed color since you bought them. “Especially if it is brown, I would say to toss it,” Dr. Lamb says.
Some of her favorite non-serum ways to get vitamin C include Ole Henriksen the Clean Truth Foaming Cleanser ($30, Sephora), Clinique Fresh Pressed Pure Vitamin C Powder ($31, Ulta), and Revision Vitamin C Lotion 30% ($122, Dermstore).