Key takeaways
- The most effective vitamin C serums contain L-ascorbic acid at a 10% to 20% concentration.
- Vitamin C serum can be applied both morning and night after cleansing and toning.
- Timeless 20% Vitamin C + E Ferulic Acid costs less than $30, while SkinCeuticals C E Ferulic Acid is a worthy splurge.
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.
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 to make some recommendations.
Vitamin C is an antioxidant, meaning it halts or holds off environmental and sun damage to cells. It 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 alcohol and ultra-processed foods.
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 for skin is to apply it topically.
That’s because when we eat, drink, or supplement vitamin C, also known as ascorbic acid, our skin only gets a
There’s a reason 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.
Vitamin C serum benefits
- reduces wrinkles
- protects collagen and increases production
- aids wound healing
- helps protect against sun damage
- reduces hyperpigmentation
- evens skin tone
- brightens complexion
- acts like armor against pollution and other free radicals
When to apply vitamin C serum
Apply vitamin C serum both morning and night, after cleansing and toning — if your skin can tolerate this.
One 2013 review even recommends applying a vitamin C serum every 8 hours, or twice daily for the pinnacle of protection.
Vitamin C’s protection and free radical-fighting prowess eventually wear off, but you can build up a reservoir for adequate photoprotection. This can be achieved by applying every 8 hours.
Also, UV light lowers the skin’s vitamin C levels. The same 2013 review says topical vitamin C is best applied after exposure to UV light, not before.
Always use SPF with vitamin CAlthough vitamin C serum isn’t a substitute for sunscreen (in fact, sun sensitivity increases with use), the two can work together to boost the skin’s protection from damage.
Talk about an area you could seriously splurge. It’s common for vitamin C serums to tick above the $100 mark, so it’s an area especially worthy of research before handing over your precious credit card digits.
As with any products, not all serums are created equal. Components like the type and concentration of vitamin C, the ingredients list, and even the kind of bottle or dispenser make or break your serum’s benefits — and your skin.
What to look for in a vitamin C serum
- Form: L-ascorbic acid
- Concentration: 10% to 20%
- Ingredient combo: L-ascorbic acid, tocopherol (vitamin E) or glutathione, ferulic acid
- Packaging: dark or tinted glass bottles with airless delivery
- Price: not a factor in quality, but opt for the brand that fits your budget
Form
Vitamin C can appear on the ingredients label under several different names, but the one you want is L-ascorbic acid, which is the most studied and effective.
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%. A concentration that’s higher than 8% is best for maximum effectiveness. But going over
Sometimes, a higher percentage of L-ascorbic acid 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.
Patch test with high percentagesVitamin 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.
Ingredients
Look for both vitamins C and E, or L-ascorbic acid and tocopherol, respectively, on your ingredients 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 is also a good pal to vitamin C.
Then check for ferulic acid, which helps lower the pH level of vitamin C to below 3.5% 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 when possible.
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 its serums.
Expiration timeMany 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.
There are different forms of vitamin C in skin care, and L-ascorbic acid is just one type — but it’s one you want to look for.
L-ascorbic acid is a natural organic compound found in topical vitamin C products, such as powders, oils, and serums. It’s helpful for improving:
- fine lines
- wrinkles
- hyperpigmentation
- dark spots
- acne scars
The name “L-ascorbic” refers to the chemical structure of the type of vitamin C and how it reacts to light. You may have heard of ascorbic acid — the form of vitamin C used in dietary supplements taken orally. But L-ascorbic acid is given its name based on how it rotates when exposed to light.
Forms of vitamin C break down into synthetic and natural versions. L-ascorbic acid is derived from natural sources. It’s found in fruits, vegetables, and even in human skin. The epidermis contains especially high concentrations of the organic compound.
L-ascorbic acid is a trustworthy source of vitamin C because it’s thoroughly researched. It’s among the most trusted active ingredients in skin care products. L-ascorbic acid stands out from other forms of vitamin C because it’s considered active.
Since L-ascorbic acid is naturally found in the skin, it’s bioavailable (aka it can be put to use immediately). The caveat is that it can be unstable, so it can oxidize before it reaches your skin.
Other forms of topical vitamin C may be more stable, but they’re considered inactive. This means they must be converted to L-ascorbic acid before they’re of use to the skin.
Which vitamin C serums should you avoid?Studies have shown that great than 20% concentration does not increase the benefits and may cause irritation.
If you have dry, dehydrated, sensitized, or sensitive skin, you may want to opt for lighter vitamin C serums that have less than 20% L-ascorbic acid, especially if you want to apply twice per day.
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 The Ordinary’s L-Ascorbic Acid powder, which is 100% 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 powders | Cons of vitamin C powders |
|---|---|
| inexpensive if purchasing as a supplement | not 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 form | may 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, is what helps stabilize it and allows 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 serum. However, if you’re a diehard DIY-er, you can use a powder to make your own affordable 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.
Vitamin C can react when paired with certain ingredients, and some forms of the antioxidant can be unstable. To get the most out of your vitamin C serum, here’s how to use it the right way:
- Wash your face: Always start with clean skin so your vitamin C serum doesn’t mix with impurities.
- Use a toner or essence to balance skin’s pH: Avoid toners with other acids and exfoliants.
- Apply vitamin C to the face, neck, and chest: Look for a vitamin C serum that also contains vitamin E and ferulic acid, which can increase the stability and effectiveness of L-ascorbic acid.
- Moisturize to form a protective seal around skin: Avoid creams with retinol.
- Apply sunscreen: Vitamin C serums may increase your skin’s sensitivity to sunlight.
L-ascorbic acid is a form of vitamin C. It’s naturally derived and found in human skin. Though it’s unstable, it’s an active form of vitamin C, so it’s bioavailable and ready for immediate use.
High concentration vitamin C serums can cause irritation. Vitamin C can cause reactions when mixed with certain active ingredients, such as retinol and other acids. It can also increase sensitivity to sunlight, so always apply sunscreen after using a vitamin C serum.
You can use vitamin C serum at any time of the day, ideally morning and night if your skin can tolerate it. According to Joan Paul, MD, MPH, it’s especially ideal to use at nighttime when natural skin repair occurs.
However, if you use retinol at night, stick to using vitamin C serums during the day only. Don’t mix these products.
It’s still beneficial to apply vitamin C in morning, because it also enhances the protective benefits of SPF. Always use SPF when using vitamin C during the day.
Apply your vitamin C serum before your moisturizer, facial oil, and sunscreen. But you can use a face wash and toner before your vitamin C serum.
Most people can benefit from using a vitamin C serum in their skin care routine. Vitamin C, especially L-ascorbic acid, is a highly researched active ingredient that has been shown to have antioxidant properties. Though it’s unstable, it’s bioavailable and therefore highly regarded in the cosmetic industry.
Using a vitamin C serum has many benefits. The antioxidant fends off free radicals from environmental stressors like pollution, sunlight, and harsh weather conditions. Apply a vitamin C serum to boost skin brightness — just pair with vitamin E, ferulic acid, and SPF for best results.
