COSRX • Serum

Advanced The Vitamin C 23 Serum, 20ml (0.7oz)

Prices & ratings as of Oct 4, 2026 · may change anytime on Amazon & Olive Young · check the retailer for current info

Upgraded version of COSRX's high-strength vitamin C serum: the bottle reads "Advanced The Vitamin C 23" — the same product Amazon lists as "COSRX 23% Pure Vitamin C Serum with Vitamin E, Glutathione" (0.7oz / 20g). At 23% pure vitamin C it may reduce the appearance of dark spots and uneven tone over time and helps improve the look of dullness and early fine lines, while vitamin E and hyaluronic acid keep the high concentration comfortable to wear. Same formula on both retailers, different pack: Amazon ships the single 20g bottle at $23.75 (list $25.00, about $35.45/fl oz), while Olive Young sells a 2 x 20g duo set at $46.40 (about $23.20 per bottle, list $57.00) — buy the duo only if you will genuinely use two bottles. Best for normal to resilient skin dealing with dullness or post-blemish marks; 23% is a high strength, so patch test and start every other morning. It is an antioxidant serum, not a sunscreen — pair it with broad-spectrum SPF in the morning.

Related guides: Hyperpigmentation & Dark Spots · Anti-Aging & Fine Lines