Vitamin C (Ascorbic Acid)

INCI: Ascorbic Acid

brightening

Vitamin C is a powerhouse antioxidant that brightens skin, fades dark spots, stimulates collagen synthesis, and protects against UV and environmental damage. It is one of the most popular K-beauty ingredients for glass skin.

Key Benefits

  • Brightens overall skin tone and fades hyperpigmentation
  • Stimulates collagen synthesis — reduces fine lines with consistent use
  • Potent antioxidant: neutralizes free radicals from UV and pollution
  • Inhibits melanin production for a more even complexion
  • Research shows 10-20% L-ascorbic acid reduces hyperpigmentation by 61% in 16 weeks

Potential Side Effects

  • May cause tingling or mild irritation at high concentrations (>15%) in sensitive skin
  • Oxidizes quickly — use products in dark, airtight packaging
  • Can interact with niacinamide in some formulations (use at different times of day if irritation occurs)
  • May increase photosensitivity — always pair with SPF

Frequently Asked Questions

What percentage of Vitamin C should I use?

10-20% L-ascorbic acid is most effective for brightening and anti-aging. Start with 10% if you have sensitive skin. Vitamin C derivatives (ascorbyl glucoside, magnesium ascorbyl phosphate) are gentler alternatives.

Should I use Vitamin C in the morning or at night?

Morning is ideal — Vitamin C enhances SPF protection and fights daytime free radicals. However, it can be used at night too. Store in a dark place to prevent oxidation.

How do I know if my Vitamin C serum has oxidized?

Fresh Vitamin C serums are clear or pale yellow. Orange or brown color indicates oxidation — the serum has lost most of its efficacy. Discard and replace.

Can I use Vitamin C with retinol?

Yes, but use them at different times. Apply Vitamin C in the morning and retinol at night to maximize benefits and avoid potential irritation.

What are the best Korean Vitamin C products?

Top Korean Vitamin C products on Olive Young Global include SOME BY MI C-Senations Perfect Serum, Dr.Jart+, and Klairs Freshly Juiced Vitamin C Serum. Use code NORTHSTAR7 for a discount.