COSRX Advanced The Vitamin C 23 Serum is a high-strength Korean brightening treatment powered by 23% pure vitamin C to target dullness, dark spots, and uneven tone. This lightweight, fast-absorbing serum pairs potent L-ascorbic acid with super vitamin E, glutathione, and hyaluronic acid to brighten the complexion, support firmness, and leave skin looking more radiant and even. It is made for those ready to upgrade to a high-potency vitamin C.

Why This Serum Works

Pure vitamin C is one of the most researched brightening antioxidants, but it is notoriously unstable. COSRX stabilises its 23% pure vitamin C with super vitamin E (tocotrienol) and glutathione, an antioxidant network that helps the vitamin C stay effective and absorb smoothly, even on sensitive skin. Together they help neutralise the free radicals behind dullness and uneven tone, so skin looks brighter and more refined with consistent use.

Ideal For

This high-potency serum is ideal for experienced vitamin C users with dull, tired, or uneven skin who want visible brightening and smoother texture. It suits most skin types, though very sensitive or reactive skin should patch test first and build up slowly. Avoid pairing it in the same routine with retinol, AHAs, BHAs, or copper peptides to prevent irritation, using them at separate times instead.

Every ingredient is chosen to brighten and comfort the skin:

• 23% pure vitamin C (L-ascorbic acid): a high-strength antioxidant that helps brighten tone and fade the look of dark spots and acne marks.

• Super vitamin E and glutathione: antioxidants that stabilise vitamin C and support a luminous, even complexion.

• Hyaluronic acid (sodium hyaluronate): draws in moisture to keep skin plump and hydrated.

• Niacinamide and allantoin: help even the look of tone while soothing and calming the skin.

This Korean formula is fragrance-free and dermatologically tested.

1. After cleansing and toning, shake the bottle gently once or twice.

2. Apply 2-3 drops and pat gently over the face, avoiding direct eye contact.

3. Use in the morning and/or evening; new users can start a few times a week.

4. In the daytime, always follow with a broad-spectrum SPF 30 or higher.

5. Store the serum in the fridge and use within two months of opening to keep the vitamin C fresh. Patch test before first use.