# COSRX Advanced The Vitamin C 23 Serum

The Vitamin C 23 Serum, 20 g, 23% ascorbic acid second on the list.

- Brand: COSRX
- Product: Advanced The Vitamin C 23 Serum
- Price: $21.17
- Availability: In stock
- Size: 20 g
- Market: Korean market, the version sold in Korea
- Made in: Republic of Korea
- EAN (barcode): 8800311121256
- Category: Serums & Ampoules

## Key benefits

- Ascorbic acid is declared at 23 percent, second on the list right after water
- 3-O-ethyl ascorbic acid at six is a second, more stable vitamin C form working alongside the primary one
- Tocotrienols at seventeen, a stronger antioxidant vitamin E form, and glutathione at twenty-three support and extend the vitamin C's effect
- Squalane and three plant oils toward the end of the list offset the dryness a high-percentage vitamin C can leave behind
- Niacinamide at twenty-one adds a fourth brightening mechanism to an already dense stack
- No fragrance, no parfum, no essential oil on the list

## How it works

This is the vitamin C step in a morning routine, in COSRX's 20 g size. It goes on after toner, on dry skin, and before moisturizer and sunscreen. What it works on is tone: a brighter, more even look that builds over weeks of daily mornings rather than in a single application. Skin new to a vitamin C serum usually does better starting every other morning and building up from there. It suits someone who already has a cleanser, a toner and a sunscreen in place and wants one active step between them.

## How to use

1. AM, after toner, as a brightening step. Start every other day if you are new to vitamin C at this strength.
2. A few drops pressed evenly over the face, avoiding the eye area where skin is thinner and more reactive.
3. Let it fully absorb, several minutes if needed, before layering anything else on top.
4. Follow with moisturizer and sunscreen without fail, since vitamin C works best paired with daily sun protection.

## Ingredients

Aqua/Water, Ascorbic Acid (23%), Butylene Glycol, Dimethicone, Panthenol, 3-O-Ethyl Ascorbic Acid, Squalane, Sodium Hydroxide, Caffeine, Sodium Hyaluronate, Sodium Metaphosphate, Adenosine, Acetyl Glucosamine, Gardenia Florida Fruit Extract, Allantoin, Dextrin, Tocotrienols, Tocopherol, Elaeis Guineensis (Palm) Oil, Arginine, Niacinamide, Pentylene Glycol, Glutathione, Helianthus Annuus (Sunflower) Seed Oil, Methyl Trimethicone, Carthamus Tinctorius (Safflower) Seed Oil, Camellia Japonica Seed Oil, Daucus Carota Sativa (Carrot) Root Extract

## FAQ

### What is the COSRX Vitamin C 23 Serum for?

It is a high-strength brightening serum for pronounced dullness and dark spots, built on ascorbic acid declared at 23 percent, second on the list. A second vitamin C form, tocotrienols and glutathione work alongside it to extend and support the effect, for skin already comfortable with vitamin C rather than as a first one to try.

### Is 23 percent too strong for my skin?

It can be, especially if you have not used vitamin C before or your skin runs sensitive. This concentration is built for people already comfortable with lower-strength vitamin C serums who want a stronger dose. Patch test first.

### Will it cause dryness or irritation?

High-percentage ascorbic acid can be drying or mildly irritating on some skin, which is why squalane and three plant oils sit further down the list to offset that. Starting every other day rather than daily is a common way to build tolerance.

### Can I use this with a retinoid or exfoliating acid?

Most people alternate a high-strength vitamin C serum with a retinoid or acid rather than layering them the same session, since combining several strong actives at once raises irritation risk. AM for vitamin C, PM for a retinoid is a common split.

### How does this compare to buying COSRX from a US retailer?

COSRX verifies units itself. Find the verification page on cosrx.com and enter the batch number and expiration date printed on your unit, read off the package rather than from us, which is the point. 8800311121256, and batch code intact under the box.

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Page: https://korean-pharmacy.com/products/cosrx-advanced-the-vitamin-c-23-serum-1