Vitamin C serum is an antioxidant you put on your skin. Used daily, it can help protect skin from everyday sun and pollution, help even out dark spots and dullness, and support the collagen that keeps skin looking smooth. The most studied form is L-ascorbic acid, usually at 10% to 20%. Put it on in the morning after you wash your face, follow with moisturizer and sunscreen, and give it about three months. It works alongside sunscreen, never instead of it.
Vitamin C serum might be the most popular bottle in skin care right now. You've probably seen the little amber dropper bottles everywhere. It's one of the few trendy ingredients with real research behind it, but there's also a lot of confusion about which kind to buy, when to use it and what it can realistically do. Here's the plain version.
What does vitamin C serum do for your skin?
Vitamin C (also called ascorbic acid or L-ascorbic acid) is an antioxidant. Every day your skin deals with sun, smoke and pollution, which create unstable molecules called free radicals that wear skin down over time. Cleveland Clinic dermatologist Dr. Melissa Piliang explains that putting vitamin C on your skin helps offset that damage, which can mean healthier-looking skin over the years.
Here's what people usually use it for:
- Extra protection with sunscreen. Vitamin C paired with sunscreen gives better protection against sun damage than sunscreen alone. It does not replace sunscreen.
- Dark spots and uneven tone. It can help fade the look of dark spots and brighten dull skin. In one study most people saw improvement, but the effect faded once they stopped using it.
- Smoother-looking skin. Collagen is what keeps skin firm and smooth, and we make less of it as we age. Vitamin C may help protect and support it.
Isn't drinking orange juice enough?
Sadly, no. Vitamin C you eat or drink is good for the rest of you, but only a small amount reaches your skin. If skin is the goal, it has to go on your skin.
What should you look for in a vitamin C serum?
- The form. L-ascorbic acid is the most studied. Other forms are more stable on the shelf but have to be converted by your skin first.
- The strength. Cleveland Clinic suggests 10% to 20% L-ascorbic acid. Below about 10% may be too weak to do much, and above 20% is more likely to irritate without adding benefit. If your skin is sensitive, start at the low end.
- The bottle. Vitamin C breaks down with light, heat and air. Look for a dark or tinted glass bottle, not clear. Some formulas add vitamin E and ferulic acid to help keep it stable.
- Not the price. They run anywhere from about $25 to over $100, and the price doesn't tell you much. The form, the strength and the packaging matter more.
Check the color. A little yellowing is common. If your serum turns dark orange or brown, it has oxidized and won't do much anymore, so it's time to toss it. Keep the cap on tight and store it somewhere cool and out of the sun.
Morning or night?
You can use it either way, but morning is the usual advice, because it pairs well with the sunscreen you put on next. Here's the order:
- Wash your face with a gentle cleanser and lukewarm water.
- Vitamin C serum, a few drops over your face and neck.
- Moisturizer.
- Sunscreen. Every morning, even when it's cloudy.
If you use retinol at night, keep your vitamin C for the morning rather than layering the two together. Here's a simple face routine if you want the whole order in one place.
Does vitamin C serum have side effects?
Most people do fine with it. The usual complaints are stinging, redness, dryness or itching, and they're more likely with higher strengths or if you're already using other acids. Patch test on your inner arm first, start every other day if your skin is touchy, and work up. If your skin stays irritated, stop and give it a rest.
How long until you see a difference?
Be patient. Dr. Piliang says to expect about three months of daily use. She suggests taking a photo once a month without makeup, in the same light, so you can actually see the change instead of guessing in the mirror.
The simple version
Vitamin C serum is one of the extras that's worth it for a lot of people, especially if dark spots or dullness bother you. Pick L-ascorbic acid at 10% to 20% in a dark bottle, use it in the morning under your moisturizer and sunscreen, and give it a few months. And if you only do one thing, make it sunscreen. If you're curious about other ingredients, here's what hyaluronic acid does, what actually helps with dark spots, and a look at retinol alternatives.
What we use in our house
Apple Firming Complex
It's not a vitamin C serum, but vitamin C, Kakadu plum and camu camu are all on its ingredient list. It's a lightweight cream-serum with Swiss green apple stem cells, bamboo and a botanical alternative to retinol (chicory root and tara). It hydrates and helps skin look firmer, smoother and more supple over time. Use it after serum and before moisturizer, morning or night. Through Sunday, Oct 25: free with any $60 order.
See the Firming Complex →
Lauren Stewart makes Tyme Soap by hand on our family farm in Idaho, with milk from our own goats.
