COSRX The Vitamin C 13 Serum - 20ml

Cosrx The Vitamin C 13 Serum is a potent brightening serum with 13% pure ascorbic acid (L-ascorbic acid), the gold standard form of vitamin C that helps brighten, even skin tone, boost collagen, and protect against UV-generated free radicals. The 13% concentration is ideal for beginners to intermediate vitamin C users, effective enough for visible results, gentle enough for daily use.

3-O-Ethyl ascorbic acid provides a stable vitamin C derivative that continues working as the pure form oxidises. Tocotrienols (super vitamin E) are 40-60x more potent than regular tocopherols as antioxidants. Glutathione, the bodys master antioxidant, amplifies the brightening effect. Niacinamide adds pore-refining benefits. Squalane moisturises. Licorice root, caffeine, panthenol, and adenosine round out a comprehensive brightening and anti-aging formula.

Why customers love it

• 13% pure ascorbic acid: gold standard vitamin C
• 3-O-Ethyl ascorbic acid: stable vitamin C derivative backup
• Tocotrienols: super vitamin E, 40-60x more potent than regular E
• Glutathione: master antioxidant brightener
• Niacinamide: pore-refining and tone-evening
• Squalane: lightweight moisture and stability
• Adenosine: anti-wrinkle and firming
• Beginner-friendly: effective yet gentle 13% concentration

Perfect for: dark spots, uneven tone, dull skin, hyperpigmentation, anti-aging, sun damage, fine lines, antioxidant protection.

Ascorbic Acid (13%) , pure L-ascorbic acid for brightening and collagen

3-O-Ethyl Ascorbic Acid , stable vitamin C derivative

Tocotrienols , super vitamin E antioxidant (40-60x more potent than tocopherol)

Glutathione , master antioxidant and skin brightener

Niacinamide , pore-refining and tone-evening vitamin B3

Sodium Hyaluronate , hydrating humectant

Squalane , lightweight moisture and formula stabiliser

Licorice Root Extract , natural brightening and soothing

Caffeine , antioxidant and circulation boost

Panthenol , soothing vitamin B5

Adenosine , anti-wrinkle and firming

Gardenia Fruit Extract , natural antioxidant

1. After cleansing and toning, dispense 3-4 drops onto your fingertips.
2. Gently pat and press across your face, focusing on dark spots.
3. Follow with moisturiser.
4. Use in the morning for antioxidant protection, or evening for repair.
5. Always apply sunscreen in the morning (vitamin C + SPF = maximum protection).

Pro tip: This is the entry-level concentration in Cosrx's vitamin C range, start here before graduating to the 23% version. Pure ascorbic acid is pH-dependent and works best on bare, slightly acidic skin, so apply immediately after cleansing before any other actives. Store in a cool, dark place and use within 3 months of opening, if the serum turns dark amber/brown, it has oxidised and should be replaced. The tocotrienols are a standout ingredient here, they're the superior form of vitamin E that most brands don't use because they're expensive. Vitamin C + E + glutathione creates a synergistic antioxidant network more powerful than any single ingredient.