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Whether you’ve been looking to simplify your skin care routine or amp it up, a vitamin C serum might be your golden ticket. Topical vitamin C is a multipurpose workhorse that can protect, repair, and enhance your skin.

But, as with any products, not all serums are created equal. Components like the type and concentration of vitamin C, the ingredient list, and even the kind of bottle or dispenser make or break your serum’s benefits — and your skin.

But don’t worry, decoding which serum to buy isn’t that hard. We’ve got the facts on C serum benefits, how to choose one (plus recommendations), and tips on how to make the most use of them.

Here are some products that we recommend:

  • C E Ferulic by SkinCeuticals
  • Vitamin C, E + Ferulic Acid Serum by Marie Veronique
  • C-Firma Day Serum by Drunk Elephant
  • Mad Hippie Vitamin C Serum
  • Revitalist Derm Intensives Vitamin C Face Serum by L’Oreal Paris
  • 20% Vitamin C + E Ferulic Acid Serum by Timeless
  • Beauty Shield Vitamin C Pollution Prevention Serum by e.l.f

Vitamin C is an antioxidant, meaning it halts or holds off environmental and sun damage to cells. And while you can count your morning OJ as a good defense for your bod, the best way to achieve vitamin C’s protection and benefits is to apply it directly onto your skin.

But there’s also a reason why you don’t want to just be placing citrus slices on your cheeks. When you DIY, there’s no control over the quality — and sometimes it’s not even safe. It’s also just not efficient.

That’s because when we eat, drink, or supplement vitamin C, also known as ascorbic acid, our skin only gets a small fraction of the benefits. However, pressing vitamin C in serum form, after it’s been chemically altered, actually lets our skin absorb more of it in an efficient way.

If you’re wondering when to apply a vitamin C serum, the answer is both morning and night, after cleansing and toning. One study even recommends applying a vitamin C serum every eight hours, or twice daily for the pinnacle of protection.

Vitamin C has photoprotective properties and staves off oxidative stress from the free radicals we meet throughout our day. Think car exhaust, cigarette smoke, certain chemicals, even booze and overprocessed foods.

But don’t worry if you skip an application. Unlike sunscreen, moisturizers, or oils, vitamin C can’t be wiped or washed off that easily.

Vitamin C’s protection and free radical-fighting prowess eventually wears off, but you can build up a reservoir for adequate photoprotection. This can be achieved by applying every eight hours.

Also, UV light lowers the skin’s vitamin C levels. It’s been found that topical vitamin C is best applied after exposure to UV light and not prior.

Always use SPF with vitamin C

Although vitamin C serum isn’t a substitute for sunscreen (in fact, sun sensitivity increases with use), the two together can work in tandem to boost the skin’s protection from damage.

You might be ready to hit the buy button, but choosing a vitamin C serum that will actually go to work for your skin involves a bit of product research. We delved into the science and made some recommendations.

What to look for in a vitamin C serum

Form: Vitamin C can appear on the ingredient label as several different names, but the one you want is L-ascorbic acid, which is the most effective. An older study comparing common vitamin C derivatives with L-ascorbic acid didn’t show an increase in absorption.

Make sure this good-guy ingredient is close to the top of the label, ideally as one of the first five ingredients.

Concentration: The sweet spot for the concentration level is between 10 and 20 percent. You definitely want a concentration that’s higher than 8 percent for maximum effectiveness. But going over 20 percent could lead to irritation and doesn’t increase its benefit.

Patch test with high percentages

Vitamin C is mostly safe to use, but in rare instances, side effects may occur, like stinging, redness, dryness, or a yellowish discoloration. As with any new product, try a patch test first before a full application.

Ingredient: Look for both vitamins C and E, or L-ascorbic acid and tocopherol respectively, on your ingredient list. Think of these skin boosters as besties that do well together.

Vitamin E stabilizes vitamin C for maximum skin protection. Another antioxidant called glutathione also is a good pal to vitamin C.

Then check for ferulic acid, which helps lower the pH level of vitamin C to below 3.5 percent so your skin can easily slurp up the cocktail.

Packaging: Exposure to air, light, and heat can degrade your serum. Look for a product that comes in a dark glass bottle featuring a medicine dropper delivery, rather than an air pump.

A tube also works. Some retailers suggest storing the product in the refrigerator to prolong its shelf life. A thoughtful brand will include label instructions on how to store their serums.

Expiration time

Many serums are yellow, but if your product takes on a brown or dark orange hue, it’s time to toss because it’s gone bad. If your serum starts out clear and turns yellow, that’s also a sign it’s oxidizing and will be less effective.

Price: Factors like concentration and formulation determine a vitamin C serum’s quality, not the price tag. Prices run the gamut from $25 to more than $100.

Keep in mind that a higher percentage of L-ascorbic acid doesn’t always mean a better product. Sometimes it can be too strong for your skin, causing it to react via purging, breakouts, or itchiness. You don’t want the product to sting and itch even after you apply moisturizer.

SerumPrice and appealConcentration/formulation
C E Ferulic by SkinCeuticals$166, serious skin care splurge and viral favorite for correcting oxidationPacks the perfect triple threat against damage: L-ascorbic acid (15%), plus vitamin E and ferulic acid.
Vitamin C, E + Ferulic Acid Serum by Marie Veronique$90, certified clean, cruelty free, and perfect for sensitive skinBlended with 5% ascorbic acid, 2% vitamin E, and 5% ferulic acid, this serum is perfect for sensitive skin. Applying twice a day will help you get the 10% your skin needs.
C-Firma Day Serum by Drunk Elephant$80, cult-status front-runner for exfoliating and hydrating benefitsA perfect combo of enzymatic ingredients, hyaluronic acid, L-ascorbic acid (15%), vitamin E, and ferulic acid.
Mad Hippie Vitamin C Serum$33.99, GMO-free, vegan, natural, cruelty-free findPretty much everything you could want: L-ascorbic acid, vitamin E, ferulic acid, hyaluronic acid, and konjac root for protection.
Revitalist Derm Intensives Vitamin C Face Serum by L’Oreal Paris$30, widely available favoriteA lower concentration of L-ascorbic acid (10%) for folks prone to irritation. Plus, skin-smoothing silicone for immediate results and hydrating hyaluronic acid.
20% Vitamin C + E Ferulic Acid Serum by Timeless$26, budget-friendly powerhouse without essential oilsHydrates with a modified form of hyaluronic acid, plus features a trifecta of L-ascorbic acid (20%), vitamin E, and ferulic acid.
Beauty Shield Vitamin C Pollution Prevention Serum by e.l.f$16, drugstore grab and goThe percentage is unknown, but for a drugstore product, the formulation of vitamin C, E, glycerin, and hyaluronic acid is primed for all skin types to apply freely.
Which vitamin C serums should you avoid?

If you have dry, dehydrated, sensitized, or sensitive skin, you may want to opt for lighter vitamin C serums that have less than 20 percent L-ascorbic acid, especially if you want to apply twice per day. If the serums you like are on the higher end, dilute it with a moisturizer with each use. Since your skin only uses 10 percent of vitamin C’s benefits, you may not need full power with each application.

Got too many skin potions already? You can add a daily pinch of vitamin C powder to an existing serum or moisturizer in your routine.

You may have seen some skin care lines touting C powders, like Philosophy’s turbo booster version, which is nearly 100 percent ascorbic acid. Or you can snag a food-grade supplement powder, like NutriBiotic, at your favorite vitamin retailer for a fraction of the cost.

Pros of vitamin C powdersCons of vitamin C powders
inexpensive if purchasing as a supplementnot as convenient (requires mixing)
adjustable (use less or more in your moisturizer or DIY serum)could cause irritation at high concentrations
longer shelf life in powder formmay not stay as sanitary over time

Keep in mind that the combo of vitamin C with other specific ingredients, like vitamin E and ferulic acid, are what help stabilize it and allow your skin to absorb it.

So, playing chemist in your bathroom with your own array of products may not produce the same results as buying a pre-crafted serum. However, if you’re a diehard DIY-er, you can use a powder to make your own affordable and serum with all the necessary ingredients.

Whatever brand or form you buy, the bottom line is that vitamin C is one of the best tried-and-true ingredients for your skin with lots of research to back it up. You don’t need a fancy (read pricey) version to reap vitamin C’s skin-saving rewards.

Jennifer Chesak is a medical journalist for several national publications, a writing instructor, and a freelance book editor. She earned her Master of Science in journalism from Northwestern’s Medill. She’s also the managing editor for the literary magazine, Shift. Jennifer lives in Nashville but hails from North Dakota, and when she’s not writing or sticking her nose in a book, she’s usually running trails or futzing with her garden. Follow her on Instagram or Twitter.