7 Ways to Make Your Vitamin C Work Better

Store it properly

Vitamin C is notoriously unstable, meaning that if you don’t store a product properly, you risk missing out on the ingredient’s benefits. “Vitamin C is highly sensitive to light, air and temperature changes, which can cause it to oxidize and become less effective,” says cosmetic chemist and adjunct professor at the University of Cincinnati, Kelly Dobos.

The move: Store your vitamin C skin-care product in a cool, dark location, away from heat or direct sunlight. “The best storage locations are dark places like a medicine cabinet, drawer, or even the refrigerator,” says Dobos. “Regardless of storage location, it's crucial to keep the bottle tightly sealed after each use to minimize air exposure, which can cause oxidation.”

Pay attention to packaging

Vitamin C products should be packaged in dark bottles, which helps prevent oxidation, according to Elmsford, NY dermatologist Kseniya Kobets, MD.

Pump bottles are preferable to dropper bottles since they cause less oxygen exposure, though some brands still opt for dropper bottles as they’ve developed products that don’t stabilize fast, says Dr. Kobets.

Find your ideal form of vitamin C

L-ascorbic acid, pure vitamin C, might seem like the obvious choice if you’re aiming to make the most out of your product. It’s true that L-ascorbic acid is the most well-studied form of vitamin C in skin care, and it seems to have the best potential to affect changes in skin, according to a 2017 review in The Journal of Clinical and Aesthetic Dermatology.

However, pure vitamin C has its shortcomings. “Vitamin C by itself—pure ascorbic acid—can turn brown very quickly and gives an odor,” says cosmetic chemist Ginger King.

“Some people can also experience a stinging sensation,” adds King. The problem is that formulas with vitamin C need to be formulated with a pretty acidic pH (of about four) to allow for optimal skin penetration, explains Dobos. “That low pH can cause irritation and stinging.”

Those who don’t experience irritation from L-ascorbic acid may find that pure vitamin C works for them. For others, alternative forms of vitamin C may be a better option.

All things considered, King prefers 3-o-ethyl ascorbic acid or tetrahexyldecyl ascorbate (also referred to as THD ascorbate), which your skin can convert to L-ascorbic acid. Ascorbyl glucoside is an additional vitamin C derivative with “good efficacy,” says Dobos.

Of the vitamin C derivatives, THD ascorbate “seems to have better tolerability and stability in studies,” says Dr. Kobets. “These derivatives are new to the market and are not as well studied as the original ascorbic acid vitamin C, but many show promise in building collagen, brightening skin and fighting free radicals.”

Consider the strength

The concentration of vitamin C in a product is worth taking into account, but it’s possible to have too much of a good thing. “A higher percentage of vitamin C does not necessarily make the formula better,” says Dr. Gross. “Our skin cells can become saturated with vitamin C, so at a certain point, it doesn’t help to add more. It does, however, increase your risk for irritation.”

The best concentration of vitamin C is formula-dependent, but research suggests that formulas that benefit skin without being overkill fall within the 10 to 20 percent range, per the Journal of Clinical and Aesthetic Dermatology article.

If you have sensitive skin and want to try a product with pure vitamin C, there are two ways to ease your way in, according to Dr. Kobets.

“One option is to start off with a lower concentration of ascorbic acid of around five to 10 percent, try to build up to 15 to 20 percent, beyond which is likely not going to benefit you,” she says. “A possibly better option is to trial vitamin C derivatives (aka vitamin C esters) which are inactive forms of vitamin C that require conversion to active forms, but are less irritating, more tolerated, and more stable when they come in contact with oxygen.”

Read the ingredient list

Ferulic acid and vitamin E pair well with vitamin C, says King. L’Oreal, which owns the brand SkinCeuticals of CE Ferulic Serum fame, holds a patent for its combination of vitamins C and E and ferulic acid, notes King. The company’s research has suggested that the inclusion of ferulic acid helped improve formula stability, addressing one of the main issues tied to vitamin C.

King also considers vitamin C and hyaluronic acid a prime pairing since the former can promote firmness while the latter hydrates skin.

Go with a serum

You can find vitamin C in products ranging from moisturizers to eye creams, each with their own advantages. “Sometimes, cream forms can feel better on the skin for dry and sensitive-skin people,” says Dr. Kobets.

In general, serums pack the biggest punch. “Serums tend to be the workhorse of your routine,” says Dr. Gross. “They generally have the highest percentage of active ingredients and are able to penetrate deep into skin, given their light texture.”

Apply it in the morning

As mentioned, vitamin C seems to benefit skin by neutralizing molecules called free radicals. In excess, harmful free radicals can lead to oxidative stress, resulting in pigmentation or signs of aging. Environmental factors like the sun or pollution can trigger your skin to produce free radicals.

That means that slotting vitamin C into your a.m. skin-care routine makes the most sense. “Because of vitamin C’s protective qualities, I prefer to use it in the morning,” says Dr. Gross. “This will best protect skin against damaging free radicals that are produced by the sun and pollution.” Consider vitamin C a tool for filling in the gaps of—not replacing—sunscreen’s free radical–blocking effects.