# COSRX The Vitamin C 13 Serum (Single)

Vitamin C 13% Serum, with Niacinamide.

- Brand: COSRX
- Product: The Vitamin C 13 Serum (Single)
- Price: $26.99
- Availability: Out of stock
- Market: Korean market, the version sold in Korea
- Made in: Republic of Korea
- EAN (barcode): 8809598455238
- Category: Serums & Ampoules

## Key benefits

- Ascorbic acid is declared at 13%, matching the name.
- Another, more stable vitamin C derivative sits just below it on the list.
- Caffeine and sodium hyaluronate sit in the top ten of the list.
- Niacinamide, glutathione and licorice root extract round out the formula.

## How it works

This is the vitamin C step that goes into a morning routine and stays there. It belongs after toner and before moisturizer and sunscreen, on skin that is dry rather than wet. What changes is tone rather than texture: a brighter, more even look that shows after a few weeks of consistent mornings. Sunscreen over the top is the other half of the habit, and a morning routine that includes this step should not skip it. It suits someone who wants one active step in the morning and keeps the evening free for an exfoliant or a retinoid.

## How to use

1. Use the Vitamin C 13 Serum in the morning, after toner and before moisturizer, on skin that has dried off rather than damp skin.
2. Three or four drops covers the whole face and neck. Press it in and let it settle for a minute.
3. Toner first, this second, then moisturizer, then sunscreen as the last step of the morning.
4. Once a day, in the morning. Do not stack it in the same routine as an exfoliating acid or a retinoid; give those the evening instead.

## Ingredients

Water, Ascorbic Acid(13%), Butylene Glycol, Dipropylene Glycol, Tromethamine, 3-0-Ethyl Ascorbic Acid, Panthenol, Acetyl Glucosamine, Caffeine, Sodium Hyaluronate, Sodium Sulfite, Disodium EDTA, Glutathione, Adenosine, Gardenia Florida Fruit Extract, Allantoin, Dextrin, Squalane, Tocotrienols, Tocopherol, Elaeis Guineensis (Palm) Oil, Arginine, Niacinamide, Pentylene Glycol, Glycyrrhiza Glabra (Licorice) Root Extract

## FAQ

### Is this single bottle the same formula as COSRX's other Vitamin C 13 packs?

The ingredient list here matches the direct-acid vitamin C formula COSRX sells across its Vitamin C 13 line: ascorbic acid declared at 13%, second after water, with 3-O-ethyl ascorbic acid as a second, more stable form a few entries later. Caffeine and sodium hyaluronate sit in the upper half of the list as well. Whether it is sold as a single bottle or a multipack, the same 13% ascorbic acid formula is what is inside.

### Can I use this if I have sensitive skin that reacts to strong actives?

A direct ascorbic acid serum at this declared strength can feel warm or tingly on skin unused to vitamin C, so introducing it a few nights a week before daily use is a sensible approach. No fragrance, essential oil, denatured alcohol, silicone, paraben, or added colourant appear on the list, which removes several common irritants. Panthenol and allantoin offer some calming support mid-list, but patch testing first is still worthwhile for reactive skin.

### When should I expect to see brighter, more even skin from daily use?

Ascorbic acid, glutathione, and tocopherol form an antioxidant combination that works with sustained daily use rather than a single application. Niacinamide, positioned toward the end of the list, adds a further ingredient linked to a more even-looking complexion over time. Give it consistent morning use for several weeks before judging whether your skin's tone and texture have shifted.

### What should come immediately after this serum in a morning routine?

This vitamin C serum is typically applied early, after toner and before a moisturizer or sunscreen step, since ascorbic acid performs best close to clean skin. Nothing on the ingredient list is known to conflict with a standard sunscreen applied over it. It is generally not layered in the same session as a separate strong exfoliating acid, so keeping those two treatments on different days or times of day is the more cautious approach.

### How do I make sure this single bottle is the genuine Korean-market formula and not a repackaged substitute?

The barcode on this bottle, 8809598455238, is a genuine EAN specific to this product, so matching it against your packaging is a straightforward first check. COSRX also verifies units through its own system: enter the batch number and expiration date printed on your unit at the checking page on cosrx.com, reading the codes straight off the box. Using both checks together, rather than relying on a seller's claim, is the reliable way to confirm what you have.

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Page: https://korean-pharmacy.com/products/cosrx-the-vitamin-c-13-serum-single