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The Niacinamide 15 Serum

Oily SkinSerum

The Niacinamide 15 Serum — Reddit Reviews

by COSRX

91nextscore8 verdicts

Updated October 6, 2026

15% niacinamide for oil control and smoother-looking pores; can sting.

What the community says

Backed by 56 studies

Redditors use this for oil control, pores, and post-acne mark fading, with a lightweight feel that layers easily. The catch is the 15% niacinamide hit can sting reactive skin, so sensitive folks often start slow.

From Reddit

Backed by 7 threads from r/koreanskincare, r/AsianBeauty and 1 more.

Read the threads ↓

What people love

Watch out for

  • 15% can burn reactive skin
  • Night-only for some users
  • Not the low-dose pick for sensitive skin

Product details

Skin Type

Key Ingredients

Skin type data limited

Where to buy

What the science says

  • Acne

    Some evidence

    Niacinamide: 6 studies tested it on its own. See all 17 studies

    What the studies found
    • Most studies found niacinamide helped acne
    • It often cleared acne about as well as clindamycin
    • Some studies found fewer red, sore spots with 4% niacinamide
    • Some evidence was uncertain, and some studies found no clear difference

    Studied at 4–10%this product: 15%

  • Hyperpigmentation

    Some evidence

    Niacinamide: 5 studies tested it on its own. See all 24 studies

    What the studies found
    • All of these studies found niacinamide helped fade dark spots or patches
    • Niacinamide 5% faded dark spots more than a placebo in studies of sun-damaged skin and dark patches
    • Used with salicylic acid peels, niacinamide improved dark patches more than peels alone
    • A niacinamide mix faded dark spots better than niacinamide alone in one study
    • One study found the fading effect reversed after niacinamide was stopped

    Studied at 2–10%this product: 15%

  • Skin Barrier

    Not proven yet

    Few or mixed studies. This claim isn't established.

    Niacinamide: 1 study tested it on its own. See all 17 studies

    What the studies found
    • All studies found it helped the skin barrier
    • It lowered water loss through the skin
    • It made the outer layer of skin thicker

    Studied at 4–5%this product: 15%

Research context, not treatment advice. Studies are about the ingredient, not necessarily this exact product.

Real Reddit threads — 10 mentions across 7 threads

COSRX The Niacinamide 15 Serum on Reddit, in one place — 7 threads from r/koreanskincare, r/AsianBeauty and 1 more, summarized.

“Niacinimide serum (night only)”

Positive

“I am currently using a COSRX regimen and it’s completely transformed my skin.”

Positive

“I have almost no visible acne and my skin feels so smooth, tight, but hydrated.”

Positive

“After I wash my face, I put a tiny bit of Cosrx Niacinamide & Zinc Serum.”

Positive

“It cuts down the oil that messes up your makeup later.”

Positive

“Thai here 👋 After I wash my face, I put a tiny bit of Cosrx Niacinamide & Zinc Serum.”

Positive

“It burned my skin but my skin tolerates Cosrx niacinamide 15.”

Mentioned

“So not sure about the formulation.”

Mentioned

“Cosrx niacinamide 15”

Mentioned

“COSRX The Niacinamide 15 Serum”

Positive

“The serum is what made a big difference in acne and appearance of pores for me”

Positive

“but every step is important”

Positive

“Recommended: COSRX 15% Niacinamide Face Serum”

Positive

“It absorbs fast and feels lightweight.”

Positive

“I can use it every day with no problems.”

Positive

“COSRX 15% Niacinamide Face Serum (websites I mentioned, Amazon and TJ Maxx/Marshalls).”

Mentioned

“There are more expensive ones you can try if you're not feeling the DT.”

Mentioned

“A lot of people who describe their skin the way you describe yours experience benefits from a niacinamide serum.”

Mentioned

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