Compare Products: The Niacinamide 15 Serum vs Seeking C Vitamin C Face Serum

COSRX

The Niacinamide 15 Serum

Mid-range15%
$25 / 20ml — $1.25/ml
Eight Saints

Seeking C Vitamin C Face Serum

Mid-range
$36 / 30ml — $1.20/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
Eight Saints
  • Those who prefer natural and plant-based skincare ingredients
  • Users seeking a gentle vitamin C derivative over L-ascorbic acid
  • People who enjoy strongly scented skincare products
  • Those looking for a hydrating vitamin C serum with botanical extracts
  • Users comfortable with essential oil-containing products

Key Ingredients

COSRX

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

Eight Saints

Sodium Ascorbyl Phosphate, MSM (Methylsulfonylmethane), Botanical Hyaluronic Acid, Aloe Leaf Juice, Vitamin E (Tocopherol), Jojoba Oil

Product Composition

10% similarity (4 ingredients in common)

Shared Ingredients
1ethylhexylglycerinsodium phytatetocopherol
Only in COSRX (12)
waterpentylene glycolniacinamidebutylene glycolacetyl glucosamine2-hexanediolzinc pcatrehalosexanthan gumpullulanallantoincitric acid
Only in Eight Saints (25)
aquamsmbotanical hyaluronic acidaloe barbadensis leaf juicesimmondsia chinensis (jojoba) seed oilcentella asiatica extractequisetum arvense extractgeranium maculatumtaraxacum officinale extractphenoxyethanolpotassium sorbatealcohollitsea cubeba fruit essential oilcitrus bergamia (bergamot) peel oilcitrus limon (lemon) peel oilcitrus paradisi (grapefruit) peel oilcitrus aurantifolia (lime) oilzingiber officinale (ginger) root oilcinnamomum camphora (ho wood) oilcymbopogon flexuosus (lemongrass) oilcymbopogon nardus (citronella) oilpogostemon cablin (patchouli) oilcananga odorata (ylang ylang) flower oilcinnamomum zeylanicum (cinnamon) leaf oilcitrus aurantium amara (neroli) flower oil

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.

Eight Saints
Scent is polarizing

Users either love or dislike the strong citrus-herbaceous scent. Those who enjoy essential oils often rate it highly; fragrance-sensitive users find it overwhelming.

Skin feels hydrated and softer

Multiple reviewers note improved skin softness and hydration within the first week. The aloe, hyaluronic acid, and jojoba oil contribute to this effect.

Some users report irritation

A portion of reviewers experience stinging, redness, or irritation, likely from the essential oil blend. The cinnamon and citrus oils are common triggers.

Gradual brightening

Users who tolerate the formula report gradual brightening over several weeks. Results are described as subtle rather than dramatic.

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