If you have oily or acne-prone skin, then you’ve probably heard about niacinamide. It’s a holy grail ingredient when it comes to brightening, calming acne, and reducing oil.

I recently tried the COSRX The Niacinamide 15 Serum, and let me tell you — it’s one of the lightest and most comfortable serums I’ve ever used. Here’s how it went!

✨ What It Claims

This serum contains 15% niacinamide, which is quite a high concentration. COSRX says it helps with:

  • Controlling excess oil
  • Reducing breakouts
  • Minimizing the look of pores
  • Fading dark spots and post-acne marks
    Smoothing out uneven skin texture

It comes in a 20ml dropper bottle, and it’s fragrance-free — always a bonus for those with sensitive skin.

💧 First Impressions

The texture is SO light — honestly, it’s the lightest niacinamide serum I’ve ever tried. It absorbs in seconds, and doesn’t leave any stickiness or greasiness behind. I loved how fresh and smooth my skin felt right after applying it.

Also, the packaging is elegant and neat!

🧴 How I Used It

I used 2–3 drops every night, right after cleansing and before moisturizing.

Important note: I didn’t use any other serum during this time, because I really wanted to see what this one could do on its own.

🧪 What I Noticed (After 3 Weeks)

Here’s what I personally experienced:

Even though I don’t have constant acne anymore, I sometimes get 1 or 2 small breakouts, especially around my cheeks. While using this serum, I noticed:

  • My skin stayed less oily throughout the day
  • Pores looked smaller and less noticeable
  • Those occasional breakouts healed faster than usual
  • My skin texture felt smoother Some of my old acne marks started to fade

I didn’t experience any irritation or purging, which surprised me for a 15% formula!

🧾 Key Ingredients (And What They Do)

Here’s a quick breakdown of the main ingredients in this serum and why they matter:

  • Niacinamide (15%) – Brightens the skin, controls oil, reduces acne, fades dark spots, and strengthens the skin barrier.
  • Zinc PCA – Helps reduce oil production and has antibacterial properties that support acne treatment.
  • Allantoin – Soothes and calms the skin, especially useful if you’re prone to redness or irritation.
  • Pantheonol (Pro-vitamin B5) – Moisturizes the skin and supports barrier repair, making the formula more gentle.
  • N-acetylglucosamine – Works well with niacinamide to improve skin tone and reduce hyperpigmentation.

This combination makes the serum powerful yet still balanced enough for oily and acne-prone skin types.

✅ Pros and Cons

Pros:

  • Lightweight, fast-absorbing texture
  • Non-sticky and comfortable on the skin
  • High 15% niacinamide concentration for effective results
  • Premium black glass bottle packaging
  • Fragrance-free and gentle enough for most skin types
  • Helps reduce oiliness, fade marks, and calm occasional breakouts

Cons:

  • May be too strong for beginners or very sensitive skin
  • Slightly small bottle size (20ml) .. Price is on the higher side compared to lower-concentration serums

⚠️ A Quick Tip for Sensitive Skin

Since this serum has 15% niacinamide, it might be too strong for some people, especially if you’ve never used high-strength actives before.

👉 If you have sensitive skin, I recommend trying a mini size first and doing a patch test. Better safe than sorry!

🌸 Final Thoughts

I’m honestly impressed. This serum has become a regular in my nighttime routine. It helped control my oil, healed new breakouts faster, and even made my skin look more even.

If you have oily, combination, or acne-prone skin and are looking for a hardworking serum that feels super light on the skin, this one is definitely worth trying.

🛍️ Shop It from Mini Haven

💖 https://havona.lk/product/cosrx-the-niacinamide-15-serum-20-ml/

🧪 mini also available for testing