The Most Effective Way to Use Vitamin C in Your Skin Care Routine

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Vitamin C skin products are finicky. On one hand, they provide essential antioxidants to reverse signs of aging. On the other, their solutions are often unstable and can cause irritation if used incorrectly. Here’s what you need to know to get the best results from your vitamin C products.

What is vitamin C?

Vitamin C is a nutrient also known as ascorbic acid and L-ascorbic acid, depending on how it’s sourced. It’s structurally similar to glucose and it’s water-soluble (which means it’s a sugar acid that dissolves in water). Plants and a few animals are able to produce vitamin C on their own, but humans lack the enzyme necessary for that (eye roll), so we rely on external sources like citrus and supplements to get our daily dose.

Why do we need it?

Internally, vitamin C repairs tissue damage and bolsters the immune system. It’s an incredible antioxidant we can’t live without. (Ever heard of scurvy? It ain’t pretty.)

On the outside, vitamin C is essential to skin health (i.e., getting and maintaining a glowy complexion). Several studies have found that L-ascorbic acid not only increases collagen, a naturally occuring nutrient responsible for skin elasticity that dissipates with age, but also helps skin fight off nasty UV rays. An Oregon State University study found that cigarette or vape smoke, air pollution and UV rays destroy vitamin C levels in skin, so taking supplements and using a topical L-ascorbic acid serum is fundamental to a healthy glow.

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According to Jen Novakovich, founder of The Eco Well and a member of the Society of Cosmetic Chemists, there’s actually a lot of vitamin C hanging out in the epidermis (skin), which means after we ingest it, L-ascorbic acid knows where it’s needed and heads there. Because of its antioxidant superpowers, it gets to work repairing the damage done by environmental factors by encouraging cell renewal and turnover.

How much should I use?

Dosage typically depends on a product’s potency. A serum with 10% L-ascorbic acid is ideal. This formula is the most bioavailable, meaning it immediately absorbs into skin and starts working. A few drops are all you need. If you start breaking out or seeing blackheads, you’re using too much—and wasting your stash!

Think about vitamin C skin care products—like Clinique’s Fresh Pressed Daily Booster or Perricone MD’s Vitamin C Ester Serum—as investments in your beauty routine. Yes, they can be pricey, but according to a rep at a leading skin care company, one bottle of serum should last four to six months if used as directed.

Pro tip: One terrific vitamin C product is better than five mediocre products. Find one that works for you and don’t layer others on top of it.

How can I make sure it’s working?

Exfoliate. Ever heard of the stratum corneum? Us either. It’s the outermost layer of skin—or more accurately, lots of dead skin cells. The life cycle of a skin cell is roughly three to four weeks (this fact comes back later, so stay with us). Studies have found that these dead cells hinder the absorption of L-ascorbic acid, so regular gentle exfoliation is a good idea to enhance results. It may even be worth trying a product like MedPeel AHA 10% Vitamin C Daily Exfoliator to save time.

Another way to ensure your vitamin C product meets its full potential is to pair it with vitamin E. The Oregon State study noted that these two working together are way more effective at repairing damaged skin cells and protecting against UV exposure than either one solo (and using vitamin E on its own is pretty useless). We highly recommend VivierSkin C E Peptides.

Pro tip: If you have super-oily skin, avoid vitamin E. It’s been known to act up on oilier complexions.

How often can I apply?

The rep we spoke with literally said, “Apply every day from age 18 until you die.” Dramatic? Maybe. True? Very. Vitamin C is the crux of any anti-aging skin care regimen. That being said, applying a few drops once at night and once in the morning is all you need.

Pro tip: If you use a retinol treatment at night, do not let vitamin C join that party. They don’t like each other and there will be evidence. Stick to vitamin C products during the day (when Sunday Riley’s C.E.O. Brightening Serum can better protect you from UV exposure) and let retinol go solo in the evening.

When should I toss it?

It can take a full skin cell cycle (three to four weeks) to see legitimate results. In that time, you may experience some irritation or blackheads. Stick with it!

If, however, it’s been more than four weeks and there’s no end in sight, try a different vitamin C route. Be sure to invest in a medical-grade product, like Obagi Professional-C Serum, as some items on the shelves contain fillers, silicones or oils that your skin may reject. There are also less intense vitamin C moisturizers on the market.

It’s worth checking to see if your product has expired—and not just by looking at the expiration date. Again, L-ascorbic acid is highly unstable, which means contact with heat, light and even air can weaken its potency. A deep yellow or brownish color means the active ingredients have oxidized and your serum is done for.

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Freelance Writer

Sarah Ashley is a Chicago-based freelance journalist. She has covered pets for PureWow for six years and tackles everything from dog training tips to the best litter boxes. Her...