COSRX

COSRX The Niacinamide 15 Serum

Name: The Niacinamide 15 Serum
Brand: COSRX
Price: 25 USD
Availability: InStock

Serum·Mid-Range·$25 / 20ml — $1.25/ml

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COSRX The Niacinamide 15 Serum$25 / 20ml — $1.25/ml

COSRX Soko Glam Amazon Ulta

Formulation Summary

A high-concentration 15% niacinamide serum designed for comprehensive acne care. The formula pairs niacinamide with 2% acetyl glucosamine (a synergistic brightening partner) and 1% zinc PCA for oil control. Only 15 ingredients total. Clinically tested by Dermacosmetic Skin Science Laboratory.

This serum prioritizes active concentration and ingredient synergy. Niacinamide at 15% sits between the standard 10% serums and maximum-strength 20% treatments. Acetyl glucosamine (NAG) works synergistically with niacinamide for enhanced hyperpigmentation reduction. Zinc PCA controls sebum and has antimicrobial properties. Allantoin soothes inflammation. Trehalose and pullulan provide lightweight hydration and a subtle skin-tightening effect. The minimal 15-ingredient formula reduces irritation potential.

Quick Facts

TextureLightweight gel-serum; absorbs quickly without residue or stickiness

ColorClear

Fragrance-free✓ Yes

Cruelty-free✓ Leaping Bunny (COSRX brand; parent company is not cruelty-free)

Vegan✗ No — Cruelty-free but parent company (Amorepacific) is not

ScentFragrance-free; no detectable scent

Designed For

•Oily and acne-prone skin seeking serious oil control
•Post-acne marks and hyperpigmentation
•Enlarged pores and textured skin
•Users ready to step up from 10% to higher-strength niacinamide
•Those who prefer minimal-ingredient formulas

May Not Suit

•Very sensitive skin; the 15% concentration is potent
•Dry skin types without layering hydration underneath
•Users seeking hydrating or plumping effects (this is oil-control focused)
•Those with ethical concerns about parent company testing policies

Key Ingredients

Ingredient	Concentration	Function
Niacinamide	15%third-party estimate	Controls sebum, minimizes pores, fades post-acne marks, strengthens barrier, and soothes inflammation. At 15%, this provides stronger effects than standard 10% serums.
Acetyl Glucosamine	2%brand-confirmed	Amino sugar naturally found in skin. Works synergistically with niacinamide to enhance brightening effects. Also promotes hyaluronic acid production and provides gentle exfoliation.
Zinc PCA	1%brand-confirmed	Combines zinc with L-PCA (a natural moisturizing factor). Reduces sebum production, inhibits acne bacteria growth, and supports skin repair without drying.
Allantoin	0.1%brand-confirmed	Soothing agent that promotes skin regeneration and collagen synthesis. Helps calm irritation from active breakouts.

The Formulation Explained

15% niacinamide and oil control

The combination of 15% niacinamide and 1% zinc PCA targets oil production from multiple pathways. Clinical testing by Dermacosmetic Skin Science Laboratory showed sebum reduction in 4 weeks. Individual results vary based on skin type and baseline oil production.

Acetyl glucosamine for brightening

The 2% acetyl glucosamine works synergistically with niacinamide for hyperpigmentation. This combination is well-researched. Brightening effects are cumulative and require 4-8 weeks of consistent use.

Pore appearance and texture

Niacinamide at this concentration has substantial research supporting pore-minimizing effects. Pore reduction typically refers to appearance rather than structural change. The pullulan creates a temporary skin-tightening effect when it dries.

Minimal 15-ingredient formula

The short ingredient list reduces irritation potential. Allantoin at 0.1% soothes inflammation from active breakouts. Results require consistent twice-daily use.

Ingredients to Know

Pentylene GlycolComedogenicity: 0/5Irritancy: 0/5

Solvent and humectant with antimicrobial properties. Well-tolerated and helps enhance ingredient penetration.

PullulanComedogenicity: 0/5Irritancy: 0/5

Polysaccharide that creates a temporary skin-tightening effect when it dries. Helps pores appear smaller immediately.

EthylhexylglycerinComedogenicity: 0/5Irritancy: 1/5

Preservative booster and skin conditioning agent. Generally well-tolerated.

User Feedback Patterns

Oil control standout:Users consistently report significant reduction in daytime oil and shine. Many describe it as the best niacinamide serum they have tried for sebum control.

Lightweight texture praised:Unlike some high-concentration serums, this absorbs quickly without tackiness or residue. Layers well under other products.

Small bottle concern:The 20ml size (vs. 30ml standard) is a common gripe, especially given the price point.

Pore improvement takes time:Users report visible pore improvement around the 3-4 week mark with consistent twice-daily use.

Full INCI List

16 ingredients · Click "Show full list" to view

About COSRX

Founded2013

FounderJun Sang Hun (Sanghoon Jeon)

LocationSeoul, South Korea

CertificationsLeaping Bunny (COSRX brand)

Discloses key ingredient concentrations on packaging. Publishes clinical study results. Simple, no-frills packaging keeps costs down. However, parent company Amorepacific sells in markets where animal testing is required by law.