Vitamin C is one of the most studied ingredients in skincare — and one of the most misunderstood. Here’s what the science actually says about how it works and how to use it well.
What vitamin C does
Vitamin C is a potent antioxidant that neutralizes free radicals generated by UV light and pollution. It also inhibits excess melanin production, which helps fade dark spots and even skin tone, and it’s a required cofactor for collagen synthesis.
Not all vitamin C is equal
The form matters as much as the percentage. L-ascorbic acid is the most studied but also the least stable. Derivatives like THD ascorbate are gentler and far more stable, making them ideal for daily use and sensitive skin.
- L-ascorbic acid — potent but unstable; oxidizes quickly.
- THD ascorbate — stable, oil-soluble, gentle on sensitive skin.
- Sodium ascorbyl phosphate — stable and good for blemish-prone skin.
How to use it
Apply vitamin C in the morning, after cleansing and before moisturizer and sunscreen. It pairs especially well with sunscreen, boosting your daytime antioxidant defense. Look for opaque, air-restricting packaging to keep the formula effective.
What to expect
With consistent use, most people see a brighter, more even complexion within 8–12 weeks. Our Radiance Vitamin C Serum uses 15% stabilized THD ascorbate with ferulic acid for exactly this reason.
This article is for general education and isn’t medical advice. Patch-test new products and consult a dermatologist for specific concerns.