Compare Products: The Niacinamide 15 Serum vs Mela B3 Serum

COSRX

The Niacinamide 15 Serum

Mid-range15%
$25 / 20ml — $1.25/ml
La Roche Posay

Mela B3 Serum

Premium10%
$45 / 30ml — $1.50/ml

Who It's Designed For

COSRX
  • 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
La Roche Posay
  • Those with stubborn hyperpigmentation including sunspots, age spots, and post-acne marks
  • Users seeking dermatologist-backed, clinically tested brightening products
  • People who want an alternative mechanism to vitamin C or hydroquinone
  • All skin tones; formulated to work without affecting natural skin tone
  • Sensitive skin types who need gentle but effective brightening

Key Ingredients

COSRX

Niacinamide (15%), Acetyl Glucosamine (2%), Zinc PCA (1%), Allantoin (0.1%)

La Roche Posay

Niacinamide (10%), Melasyl (2-Mercaptonicotinoyl Glycine), Sodium Hyaluronate, LHA (Capryloyl Salicylic Acid)

Product Composition

26% similarity (9 ingredients in common)

Shared Ingredients
waterpentylene glycolniacinamide1xanthan gumethylhexylglycerinsodium phytatecitric acidtocopherol
Only in COSRX (7)
butylene glycolacetyl glucosamine2-hexanediolzinc pcatrehalosepullulanallantoin
Only in La Roche Posay (18)
dimethiconepropylene glycolsilicacystoseira tamariscifolia extract2-mercaptonicotinoyl glycinepeg-20 methyl glucose sesquistearatecarnosinepoloxamer 338ammonium polyacryloyldimethyl tauratedipotassium glycyrrhizatecaprylic/capric triglyceridecapryloyl salicylic acidcaprylyl glycoloctyldodecanolretinyl palmitatepentaerythrityl tetra-di-t-butyl hydroxyhydrocinnamatephenoxyethanolparfum/fragrance

User Feedback Patterns

COSRX
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.

La Roche Posay
Effective for post-acne marks

Users frequently report fading of post-inflammatory hyperpigmentation from acne. Often noted as more effective than previous vitamin C serums.

Gentle on sensitive skin

Despite fragrance, many sensitive skin users report no irritation. Users with rosacea have noted tolerance.

Gradual results

Users report seeing changes over weeks to months. Not overnight results, but consistent improvement with regular use.

Texture praise

Lightweight serum absorbs quickly without greasiness. Layers well under sunscreen and makeup.

Mixed expectations

Some users with stubborn melasma or very dark spots report only modest improvement. Works better on newer or less severe pigmentation.

Which Should You Buy?

COSRX The Niacinamide 15 Serum offers great value at a lower price point. La Roche Posay Mela B3 Serum may be worth the premium if you want Niacinamide (10%).

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