COSRX Pure Vitamin C 13% Serum — 0.67 oz Brightening Facial Serum with Hyaluronic Acid & Vitamin E

COSRX Pure Vitamin C 13% Serum is a concentrated daily vitamin C treatment with hyaluronic acid, vitamin E variants, and glutathione to hydrate skin and help even skin tone.

This lightweight Korean serum combines 13% ascorbic acid with supportive antioxidants and humectants to target dullness and uneven pigmentation while delivering hydration. The formula is designed to absorb quickly without a sticky finish and can be worn under sunscreen during daytime routines. Packaged in a 0.67 oz bottle, it’s intended for targeted brightening and moisture support when used consistently and stored properly to limit oxidation.

How should I apply this serum in my daily skincare routine?

Shake the bottle once or twice before dispensing to mix active ingredients. Use 2–3 drops on cleansed skin once or twice daily, allowing it to absorb before following with moisturizer and, in the morning, a broad-spectrum SPF 30 or higher.

• Apply to clean, dry skin; avoid direct contact with eyes.
• Layer moisturizer after serum to seal in hydration.
• Use sunscreen when worn during the day to protect results.
• Store in the refrigerator after opening to slow oxidation.

What key ingredients are in the formula and what do they do?

The serum centers on 13% pure vitamin C (ascorbic acid) supported by Super Vitamin E (tocotrienol), hyaluronic acid, and glutathione. These ingredients work together to provide antioxidant protection, boost hydration, and help improve the look of uneven tone over time.

• Pure Vitamin C (ascorbic acid) — potent antioxidant for brightness.
• Super Vitamin E (tocotrienol) — supports antioxidant activity.
• Hyaluronic acid — draws and holds moisture for smoother texture.
• Glutathione — complements brightening and reduces dullness appearance.

Is this serum suitable for sensitive or acne-prone skin types?

The formulation is effective but contains active vitamin C at a relatively high concentration, which can irritate sensitive skin. Patch testing before facial use is recommended and starting with once-daily application helps assess tolerance; consult a dermatologist if you have concerns or reactions.

• Perform a 24-hour patch test on the body before facial use.
• Begin with once-daily application to build tolerance.
• If irritation occurs, discontinue and seek medical advice.
• Avoid direct eye area contact; can be applied around but not in eyes.

How do I keep the serum stable and extend its shelf life?

Ascorbic acid can oxidize when exposed to heat, light, or air; proper storage preserves potency. Keep the bottle tightly closed, store in a cool place, and refrigerate after opening to slow degradation and maintain color and effectiveness.

• Shake before use to redistribute ingredients.
• Tightly cap the bottle after each use to reduce air exposure.
• Refrigerate the serum after opening to help prevent oxidation.
• Discard if the product changes scent, color, or texture significantly.

Who is this formula best for? This COSRX serum is aimed at people looking to brighten dull skin, reduce the appearance of uneven pigmentation, and add lightweight hydration. It suits those comfortable introducing a potent vitamin C product into their routine, willing to patch test and use daily sunscreen for daytime wear. If you have very reactive skin or prefer milder actives, consider starting with lower concentrations or consult a skincare professional before use.