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COSRX The Vitamin C 23 Serum Dupes & Cheaper Alternatives

From 66 Reddit threads · Updated November 3, 2026

The Vitamin C 23 Serum
78nextscore· 34 verdicts

23% pure vitamin C fades dark marks and brightens; oxidizes quickly. The catch: stings sensitive skin and can damage the moisture barrier. Here's what Redditors reach for instead.

The short answer

  1. No.5 Vitamin Concentrated Serum
    Best Overall Alternative

    Tranexamic acid plus niacinamide for pigment-focused routines · $17.00 · 29.9 ml

  2. Dark Spot Correcting Glow Serum
    Best Cheaper Alternative

    Light gel texture that absorbs quickly without greasiness · $1.98 · 5 ml vs $20.00 for the original

  3. Intensive Anti-Spot Essence
    Same Active: Vitamin C

    Ascorbic acid visibly fades post-acne marks with consistent use

#1

Best Overall Alternative

  • Size: 29.9 ml
  • Price per ml: $0.57/ml (original $1.00/ml)

The why

This multi-active brightening serum layers easily and suits dry or combination skin chasing acne marks and uneven tone. Redditors report fading for some; studies found topical niacinamide’s acne results uncertain. People with reactive, breakout-prone skin report irritation and breakouts.

One minus

Not a true vitamin C serum; the vitamin C content is viewed as too weak

Good forSensitive Skin, Dry Skin

Both recommended for Hyperpigmentation; discussed alongside COSRX The Vitamin C 23 Serum in 9 threads.

“For one serum to cover a lot of these bases, the No.5+ Glutathione Vitamin Concentrated Serum might be a good option.”

— Reddit, r/koreanskincare

The original, at a glance

Why people love it
High-strength 23% pure vitamin C
Price
$20.00 · 20 ml · $1.00/ml

#2

Best Cheaper Alternative

  • Key actives: Niacinamide 5%
  • Size: 5 ml
  • Price per ml: $0.40/ml (original $1.00/ml)

The why

A lightweight 5% niacinamide serum for dark marks, uneven tone, and a quick glow. Reddit users describe fast absorption and occasional impressive fading, though others saw nothing after months or experienced worsening skin.

One minus

Does nothing for some users, even after four months

Both recommended for Hyperpigmentation.

“To treat the red/purple marks that remain for ages after you get rid of the initial pimples, i recommend the axis-y dark spot correcting serum!”

— Reddit, r/acne

#3

Same Active: Vitamin C

The why

This ascorbic acid essence targets post-acne marks and dullness with a tube that slows oxidation. It fits consistent morning routines for sensitive skin, though the oily feel annoys, and reactive or acne-prone users report irritation and breakouts.

One minus

Oily slip can feel greasy and slow to absorb

Good forSensitive Skin, Dry Skin

Both recommended for Hyperpigmentation; discussed alongside COSRX The Vitamin C 23 Serum in 15 threads.

“This is a really great dark spot treatment that usually works for recent PIH.”

— Reddit, r/AsianBeauty

#4

Best for Hyperpigmentation

  • Key actives: L-ascorbic acid 15%, alpha tocopherol 1%
  • Size: 30 ml
  • Price per ml: $4.93/ml (original $1.00/ml)

The why

A 15% L-ascorbic acid serum paired with 1% tocopherol and 0.5% ferulic acid for morning antioxidant support and visible tone work. It suits experienced vitamin-C users chasing pigmentation and glow, but sensitive skin may sting and oxidized bottles turn orange.

One minus

Mind-bogglingly expensive for 30 mL

Good forDry Skin, Sensitive Skin

Both recommended for Hyperpigmentation; discussed alongside COSRX The Vitamin C 23 Serum in 9 threads.

“Changes: Added CE Ferulic + tretinoin + tinted SPF”

— Reddit, r/40plusskincare

Other alternatives worth a look

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