The Vitamin C 13 Serum

COSRX The Vitamin C 13 Serum 20ml is a lightweight, water-based brightening treatment formulated with 13% pure vitamin C. The Vitamin C 13 Serum helps improve the appearance of dark spots, uneven tone and dullness while providing comfortable daily hydration.

Vitamin C 13 Serum for Daily Brightening

This daily brightening serum has a watery, non-sticky texture that absorbs quickly into the complexion. It is lighter than a high-strength vitamin C treatment, making it suitable for customers beginning a pure vitamin C routine.

The formula can be used in the morning or evening and is suitable for daily application according to skin tolerance. With consistent use, it supports a fresher, smoother and more radiant-looking complexion.

Vitamin C 13 Serum Benefits

• Formulated with 13% pure vitamin C
• Helps brighten dull and tired-looking skin
• Improves the appearance of uneven skin tone
• Helps reduce the visible appearance of dark spots
• Supports smoother and more refined-looking texture
• Provides lightweight daily hydration
• Contains vitamin E, hyaluronic acid and allantoin
• Absorbs quickly without a heavy or greasy finish
• Suitable for morning and evening routines

Daily Brightening and Hydration

The Vitamin C 13 Serum combines antioxidant care with moisturising ingredients to support a brighter complexion without a rich texture. Its water-based consistency layers easily beneath moisturiser, sunscreen and makeup.

This Korean vitamin C serum is suitable for routines focused on visible pigmentation, post-blemish marks, early signs of ageing and uneven-looking tone. Individual results will vary according to skin type, routine and consistency of use.

13% Pure Vitamin C Formula

• 13% Pure Vitamin C: Helps improve visible discolouration, dark spots and uneven-looking tone.
• Tocotrienol and Vitamin E: Provide antioxidant support against environmental stressors.
• Hyaluronic Acid: Helps replenish moisture and maintain a soft skin feel.
• Allantoin: Supports skin comfort while using active brightening ingredients.
• Panthenol: Helps maintain hydration and a comfortable complexion.

These complementary ingredients help the 13% ascorbic acid serum provide brightening care while maintaining lightweight hydration.

How to Use This Daily Brightening Serum

1. Cleanse and tone the skin before application.
2. Apply a few drops during the serum step.
3. Gently massage from the centre of the face outwards.
4. Pat lightly until the product is fully absorbed.
5. Follow with moisturiser.
6. When used in the morning, finish with sunscreen rated SPF 30 or higher.

Customers new to pure vitamin C can introduce the daily brightening serum gradually before progressing to daily use. Avoid direct application to broken or severely irritated skin.

Product Care and Storage Instructions

Keep the Korean vitamin C serum refrigerated upright at 3–10°C after opening. Use it promptly and preferably within two months to help preserve the active ingredients. Always close the bottle securely and protect it from heat, air and direct sunlight.

A slight yellow tint is normal for a pure vitamin C formula. Discontinue use if the product becomes significantly darker or if persistent irritation develops. Avoid using it alongside copper peptide products in the same routine; apply them at different times of day.

Complete Your Routine

Follow the 13% ascorbic acid serum with the Oil-Free Ultra-Moisturizing Lotion with Birch Sap for lightweight daily hydration. Explore more authentic products in the COSRX skincare collection.

Size: 20ml
Skin concerns: Dullness, uneven tone, dark spots and early signs of ageing
Product type: Daily brightening facial serum
Key ingredient: 13% pure vitamin C
Texture: Lightweight, watery and fast absorbing
Use: Morning or evening
Storage: Refrigerate upright at 3–10°C after opening
Recommended use period: Within two months of opening
Made in: Korea