Vitamin C in skincare: what it does, and how to use it right
Vitamin C is hyped for a reason — but only if you use it correctly. Concentration, order of application, and the most common mistakes.
Vitamin C is one of the few ingredients with solid research behind it for brighter, more even skin. But half the people who try it give up — because they use it wrong.
What it actually does
Vitamin C is an antioxidant. It neutralizes free radicals from sun and pollution, fades dark spots, and supports collagen. The result over a few weeks: a more even tone and more “glow.”
Concentration: more isn’t better
10–15% L-ascorbic acid is the sweet spot for most people. Higher can irritate without adding benefit. Sensitive skin? Start with a gentler form like sodium ascorbyl phosphate or THD ascorbate.
Order and timing
Use it in the morning, on clean skin, before moisturizer and sunscreen. Vitamin C plus sunscreen is a powerful pair: the serum boosts protection, and the sunscreen protects the serum.
The most common mistakes
- Storing it in light and heat — vitamin C oxidizes and becomes useless. Use an opaque bottle, kept somewhere cool.
- Layering too many actives at once. Introduce one new ingredient at a time.
- Expecting results in a week. Give it 4–8 weeks.
If the serum turns dark orange or brown, it has oxidized — time for a new bottle.
Ready to shop? See our roundup of the best drugstore vitamin C serums.
Frequently asked questions
What strength of vitamin C should I use?
For most people, 10–15% L-ascorbic acid is the sweet spot. Higher concentrations can irritate without adding benefit. If your skin is sensitive, start with a gentler form like sodium ascorbyl phosphate or THD ascorbate.
When should I apply vitamin C?
In the morning, on clean skin, before moisturizer and sunscreen. Vitamin C and sunscreen work as a team: the serum boosts your protection, and the sunscreen protects the serum.
How do I know if my vitamin C serum has gone bad?
If the serum turns dark orange or brown, it has oxidized and lost its effectiveness. Store it in a cool, dark place in an opaque bottle to slow this down.