# COSRX Niacinamide 15 vs Alpha-Arbutin 2 Serum

**Question answered:** Should I choose COSRX The Niacinamide 15 Serum or The Alpha-Arbutin 2 Discoloration Care Serum?

**Short answer:** Choose The Niacinamide 15 Serum if your main concerns are excess oil, visible pores and uneven texture; it has 15% niacinamide with zinc PCA in a short formula. Choose The Alpha-Arbutin 2 Discoloration Care Serum if dark spots or post-blemish marks bother you most; it combines 2% alpha-arbutin with niacinamide and tranexamic acid. Both are sold as fragrance free.

By Nora Ellison. Published 2026-10-28. Data is taken from manufacturer labels; the products have not been tested.

## What this means for you

### Start with what you notice

Name your biggest annoyance: shine and pores, or dark marks that linger. Each serum is aimed at one of those.

### The ingredient names, translated

Niacinamide is vitamin B3; it's widely used for oil, pores and uneven tone. Alpha-arbutin and tranexamic acid are ingredients used for the look of dark spots. The Alpha-Arbutin serum includes niacinamide too, so it covers some overlap, but its niacinamide percentage isn't stated.

### How to decide

- Oily skin, visible pores or rough texture? The Niacinamide 15 Serum.
- Dark spots or marks left after breakouts? The Alpha-Arbutin 2 Discoloration Care Serum.
- Using both? Layer one at a time and introduce them a few weeks apart.

### What to expect

Fading dark spots usually takes months and depends on daily sunscreen. A high niacinamide percentage isn't automatically better and can irritate some skin at first. We haven't tested either product.

General guidance, not a test of these products: [AAD: how to fade dark spots](https://www.aad.org/public/everyday-care/skin-care-secrets/routine/fade-dark-spots); [DermNet: postinflammatory hyperpigmentation](https://dermnetnz.org/topics/postinflammatory-hyperpigmentation). Each product's label source is linked on its product page.

## Oil and pores vs dark spots

[COSRX The Niacinamide 15 Serum](product:cosrx-the-niacinamide-15-serum) has 15% [niacinamide](/ingredients/niacinamide/), with acetyl glucosamine, zinc PCA, trehalose and allantoin. It's a 20 mL serum with 15 listed ingredients. COSRX positions it for the look of enlarged pores, excess oil, uneven texture and post-blemish marks.

[COSRX The Alpha-Arbutin 2 Discoloration Care Serum](product:cosrx-the-alpha-arbutin-2-discoloration-care-serum) has 2% [alpha-arbutin](/ingredients/alpha-arbutin/). Niacinamide and [tranexamic acid](/ingredients/tranexamic-acid/) appear above it on the list, with ferulic acid, glutathione and licorice root further down. It's a 50 mL serum with a longer, 38-ingredient formula.

> **Skin Realist check:** two serums that both say "brightening" aren't twins. One leans oil and pores, the other leans dark spots.

## Label differences worth knowing

The Alpha-Arbutin serum lists alcohol and sodium metabisulfite; the Niacinamide serum lists neither. For a broader look, see our [dark spot corrector guide](/articles/best-dark-spot-correctors/) and [acne marks guide](/articles/acne-marks-and-scars/).

## Manufacturer sources

- [COSRX The Niacinamide 15 Serum](https://www.cosrx.com/products/the-niacinamide-15-serum-%EB%B2%88%EB%93%A4)
- [COSRX The Alpha-Arbutin 2 Discoloration Care Serum](https://www.cosrx.com/products/the-alpha-arbutin-2-discoloration-care-serum)

Sources and label-check dates are recorded on the product pages.

| Product | Price | Key ingredients | Skin types | Fragrance | Flagged ingredients | Size | Source | Buy |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
| [COSRX The Niacinamide 15 Serum](https://dermalguide.com/products/cosrx-the-niacinamide-15-serum/) | $20.00 at [Stylevana](https://www.awin1.com/pclick.php?p=43018982649&a=3132625&m=90791) (affiliate), checked 2026-10-29 07:35 UTC | Niacinamide 15% | Brand doesn't say | Marketed as fragrance free | No flags recorded; not a safety guarantee | 20 ml | [Manufacturer label](https://www.cosrx.com/products/the-niacinamide-15-serum-%EB%B2%88%EB%93%A4), checked 2026-10-10 | [Amazon (affiliate)](https://amzn.to/4yL1sKV) |
| [COSRX The Alpha-Arbutin 2 Discoloration Care Serum](https://dermalguide.com/products/cosrx-the-alpha-arbutin-2-discoloration-care-serum/) | $20.00 at [Stylevana](https://www.awin1.com/pclick.php?p=43018982644&a=3132625&m=90791) (affiliate), checked 2026-10-29 07:35 UTC | Alpha-Arbutin 2% | Brand doesn't say | Marketed as fragrance free | Alcohol | 50 ml | [Manufacturer label](https://www.cosrx.com/products/the-alpha-arbutin-2-discoloration-care-serum), checked 2026-10-10 | [Amazon (affiliate)](https://amzn.to/4hSilMe) |

## Which to choose

Consider COSRX The Niacinamide 15 Serum when: Excess oil, visible pores or uneven texture are your main concern; You want a short, 15-ingredient formula.

Consider COSRX The Alpha-Arbutin 2 Discoloration Care Serum when: Dark spots or post-blemish marks are your main concern; You want alpha-arbutin, tranexamic acid and niacinamide together.


## Questions

### Can I use them together?

There's no listed conflict between them. Both include niacinamide, so start one at a time and add the second once your skin is comfortable.

### Which is bigger?

COSRX lists The Niacinamide 15 Serum at 20 mL and The Alpha-Arbutin 2 serum at 50 mL.

### Do I need sunscreen with them?

COSRX says to follow the niacinamide serum with SPF 30 or higher in the morning. Daily sunscreen matters for any dark-spot routine.