# COSRX The Niacinamide 15 Serum

Niacinamide Serum, 20 ml, with Zinc PCA.

- Brand: COSRX
- Product: The Niacinamide 15 Serum
- Price: $18.99
- Availability: Out of stock
- Size: 20ml
- Market: Korean market, the version sold in Korea
- Made in: Republic of Korea
- EAN (barcode): 8809598454637
- Category: Serums & Ampoules

## Key benefits

- Niacinamide is third on the ingredient list.
- Zinc PCA and acetyl glucosamine support the pore-refining focus.
- Trehalose and allantoin round out the hydrating, calming base.
- No percentage is declared on this bottle's own list, so none is claimed.

## How it works

A niacinamide serum is bought for how the surface looks: tone, shine, and the size pores appear to be. This is the niacinamide step in COSRX's line, a short, thin formula that goes on after toner and before moisturizer. Skin that turns shiny by midday and reads uneven in tone is the case it fits, and it is a daily step rather than an occasional one. Niacinamide is one of the few actives that sits happily in both the morning and the evening routine. Twice a day, and it layers under anything else already in place.

## How to use

1. Use the Niacinamide 15 Serum after toner and before moisturizer, morning and evening.
2. Three or four drops covers the face. Press it in rather than rubbing it across the skin.
3. Toner first, this second, then moisturizer, and sunscreen last in the morning.
4. Twice a day, every day. Do not layer it with a second niacinamide product; one step of it is enough in a routine.

## Ingredients

Water, Pentylene Glycol, Niacinamide, Butylene Glycol, Acetyl Glucosamine, 1,2-Hexanediol, Zinc PCA, Trehalose, Xanthan Gum, Pullulan, Allantoin, Ethylhexylglycerin, Sodium Phytate, Citric Acid, Tocopherol

## FAQ

### What does The Niacinamide 15 Serum actually do for the skin?

Niacinamide sits third on the list, right behind water and pentylene glycol, with Zinc PCA and Acetyl Glucosamine following close behind. That order places niacinamide near the front of a short, pore-focused formula, with trehalose and allantoin further down to round out the hydrating, calming base. The combination targets pore appearance and tone rather than acting as a broad hydrating serum.

### Is this serum suitable for oily, pore-prone skin?

The list has no fragrance, no essential oil, no added silicone, no paraben, and no mineral oil. That profile suits oily and pore-prone skin looking for a lightweight, fragrance-free niacinamide serum. This bottle's own list does not declare a percentage for niacinamide, so despite the name, no specific strength figure is claimed here.

### How long before pores or tone look different with regular use?

Niacinamide and zinc PCA both work toward a clearer, more even look with sustained daily application rather than a single dose. Visible pore appearance and oiliness tend to shift gradually across several weeks of consistent morning and evening use, not immediately. Applying it inconsistently will slow that pace considerably compared with a steady routine.

### Can I layer this serum with a retinoid or exfoliating acid?

This list does not include a retinoid or an exfoliating acid, so it is built as a standalone niacinamide step rather than a base formulated to carry either. Applying it after toner and letting it absorb before a separate treatment step is a reasonable order, but whether it pairs well with a specific acid or retinoid depends on that other product's own formula. Introduce anything new slowly and watch for irritation.

### How do I verify this bottle is the authentic Korean-market Niacinamide 15 Serum?

The bottle carries its original Korean-market barcode, 8809598454637, unaltered from the release sold in Korea. COSRX verifies its own units directly rather than leaving that job to a reseller: enter the batch number and expiration date printed on your bottle into the verification page on cosrx.com. Reading those figures off your own bottle, not off a listing photo, is what actually confirms it.

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Page: https://korean-pharmacy.com/products/cosrx-the-niacinamide-15-serum