The Vitamin C 23 Serum

CosRX

Where to buy Possibly in stock

About this product

The CosRX The Vitamin C 23 Serum is a serums, essence, ampoule. Our analysis of its 34 ingredients (25 low-risk) rates it Excellent (99/100). Based on its ingredients, it looks well-suited to oily / acne-prone and dry skin.

Vegan-friendly Reef-safe

Summarised from our ingredient analysis — not brand marketing copy.

At a glance

Type
Serums, Essence, Ampoules
Ingredients
34
Low-risk
25
Fragrance
Fragrance-free
Origin
South Korea
Data updated
Jun 2026

The evidence

Quick Product Notes

Paraben-Free Sulfate-Free Alcohol-Free Silicone-Free EU Allergen-Free Fungal Acne (Malassezia) Safe

Notable Effects & Ingredients

No Notable Effects & Ingredients

Ingredients Related to Skin Types

Good   Bad — tap a skin type to see which ingredients · estimated from ingredient functions
Dry Skin 5/2
Good for dry skin
Camellia Japonica Seed Oil Squalane Butylene Glycol Sodium Hyaluronate Dimethicone
Caution for dry skin
Dextrin Alcohol Denat.
Oily/Acne-Prone Skin 1/0
Good for oily/acne-prone skin
Alcohol Denat.
Sensitive Skin 3/7
Good for sensitive skin
Sodium Sulfite Dimethicone Allantoin
Caution for sensitive skin
Glutathione Sodium Chloride Arginine Caffeine Butylene Glycol Tromethamine Alcohol Denat.

Ingredients list

34 total
Lower hazard (1) Higher hazard (4)
All34 Skin Conditioning33 Fragrance9 Solvent6 Masking6 Viscosity Controlling6 Hair Conditioning5 Skin Protecting4 Skin Conditioning Emollient3
EWG CIR Ingredient Name & Cosmetic Functions Notes
1
Water
(Solvent)
ASCORBIC ACID
(Antioxidant, Buffering, Fragrance, Skin Conditioning)
1
Propanediol
(Solvent, Viscosity Decreasing Agent, Viscosity Controlling)
3
A
Dimethicone
(Antifoaming Agent, Skin Protecting, Emollient, Skin Conditioning)
Silicone
Silicone
2
A
Tromethamine
(Fragrance, Ph Adjuster, Buffering Agent, Masking)
1
A
Panthenol
(Antistatic Agent, Hair Conditioning, Skin Conditioning)
Good for Dry Skin
Good for Dry Skin
3-O-ETHYL ASCORBIC ACID
(Skin Conditioning)
1
A
Squalane
(Emollient, Hair Conditioning, Refatting, Skin Conditioning)
1
Caffeine
(Fragrance, Skin Conditioning, Masking)
1
Sodium Chloride
(Bulking Agent, Masking, Oral Care Agent, Viscosity Controlling)
1
A
Sodium Hyaluronate
(Skin Conditioning, Humectant)
Good for Dry Skin
Good for Dry Skin
2
A
Sodium Sulfite
(Antioxidant, Hair Waving Or Straightening, Reducing, Preservative)
1
A
Disodium EDTA
(Chelating Agent, Viscosity Controlling)
1
Glutathione
(Fragrance, Reducing)
1
Adenosine
(Skin Conditioning)
1
Acetyl Glucosamine
(Skin Conditioning)
1
Gardenia Florida Fruit Extract
(Skin Conditioning)
1
A
Allantoin
(Skin Conditioning, Skin Protecting, Soothing)
Good for Oily Skin
Good for Oily Skin
Good for Sensitive Skin
Good for Sensitive Skin
1
A
Dextrin
(Absorbent, Binding Agent, Bulking Agent, Viscosity Increasing Agent, Binding, Viscosity Controlling)
1
A
Tocotrienols
(Oral Care Agent, Skin Conditioning, Uv Absorber)
TOCOPHEROL
(Antioxidant, Fragrance, Skin Conditioning)
ELAEIS GUINEENSIS OIL
(Skin Conditioning Emollient)
1
A
Butylene Glycol
(Fragrance, Skin Conditioning, Solvent, Viscositydecreasing Agent, Humectant, Masking, Viscosity Controlling)
Good for Dry Skin
Good for Dry Skin
1
A
Arginine
(Fragrance, Hair Conditioning, Skin Conditioning, Antistatic Agent, Masking)
1
A
Niacinamide
(Hair Conditioning, Skin Conditioning, Smoothing)
1
A
Pentylene Glycol
(Skin Conditioning, Solvent)
4
Alcohol Denat.
(Antifoaming Agent, Antimicrobial, Astringent, Masking, Solvent, Viscosity Controlling)
Bad for Dry Skin
Bad for Dry Skin
Bad for Sensitive Skin
Bad for Sensitive Skin
Helianthus Annuus Seed Oil
(Fragrance, Skin Conditioning, Skin Conditioning Emollient)
glycyrrhiza glabra root extract
(Bleaching, Perfuming, Skin Conditioning, Skin Conditioning Emollient, Smoothing, Soothing)
1
Methyl Trimethicone
(Hair Conditioning, Skin Conditioning, Solvent)
Carthamus Tinctorius Seed Oil
(Fragrance, Skin Conditioning)
1
A
Camellia Japonica Seed Oil
(Emollient, Skin Conditioning)
daucus carota sativa root extract
(Skin Conditioning)
2
Beta-Carotene
(Skin Conditioning)
Good for Dry Skin
Good for Dry Skin

My Ingredient Notes

No personal ingredient notes yet. Save ingredients to your profile to get good/bad alerts here.

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Key ingredients

Vitamin C
Brightens, evens tone, and supports collagen.
Vitamin E
Protects skin and soothes irritation.
Antioxidants
Shields skin from free radical damage.
Niacinamide
Strengthens, smooths, and brightens skin.
Hyaluronic Acid
Hydrates by attracting and holding water.

Benefits

HydratingBoosts hydration and relieves dry, tight skin.
Barrier RepairStrengthen and restore your skin's natural barrier.
Scar HealingImproves the look of marks and scars.
Anti-AgingSoftens lines and helps skin look youthful.
Redness ReducingSoothes visible redness and calms irritation.
BrighteningRestores radiance to dull, tired skin.
Reduces IrritationEases discomfort and supports skin resilience.
Dark SpotsFades dark spots for even skin tone.

Concerns

Contains silicone
May not suit sensitive skin

Ingredients explained

Water
Solvent
Low-hazard ingredient.Read moreShow less
EWG 1 Solvent
ASCORBIC ACID
Antioxidant, Buffering
Limited public safety data.Read moreShow less
EWG N/A AntioxidantBufferingFragranceSkin conditioning
Propanediol
Solvent, Viscosity decreasing agent
Low-hazard ingredient.Read moreShow less
EWG 1 SolventViscosity decreasing agentViscosity controlling
Tromethamine
Fragrance, Ph adjuster
Low-hazard ingredient.Read moreShow less
EWG 2 CIR A FragrancePh adjusterBuffering agentMasking
3-O-ETHYL ASCORBIC ACID
Skin conditioning
Limited public safety data.Read moreShow less
EWG N/A Skin conditioning
Squalane
Emollient, Hair conditioning
Low-hazard ingredient.Read moreShow less
EWG 1 CIR A EmollientHair conditioningRefattingSkin conditioning
Caffeine
Fragrance, Skin conditioning
Low-hazard ingredient.Read moreShow less
EWG 1 FragranceSkin conditioningMasking
Sodium Chloride
Bulking agent, Masking
Low-hazard ingredient.Read moreShow less
EWG 1 Bulking agentMaskingOral care agentViscosity controlling
Sodium Sulfite
Antioxidant, Hair waving or straightening
Low-hazard ingredient.Read moreShow less
EWG 2 CIR A AntioxidantHair waving or straighteningReducingPreservative
Disodium EDTA
Chelating agent, Viscosity controlling
Low-hazard ingredient.Read moreShow less
EWG 1 CIR A Chelating agentViscosity controlling
Glutathione
Fragrance, Reducing
Low-hazard ingredient.Read moreShow less
EWG 1 FragranceReducing
Adenosine
Skin conditioning
Low-hazard ingredient.Read moreShow less
EWG 1 Skin conditioning
Acetyl Glucosamine
Skin conditioning
Low-hazard ingredient.Read moreShow less
EWG 1 Skin conditioning
Gardenia Florida Fruit Extract
Skin conditioning
Low-hazard ingredient.Read moreShow less
EWG 1 Skin conditioning
Dextrin
Absorbent, Binding agent
Low-hazard ingredient.Read moreShow less
EWG 1 CIR A AbsorbentBinding agentBulking agentViscosity increasing agentBindingViscosity controlling
+ 12 more — see the full ingredients list above
Dimethicone
Antifoaming agent, Skin protecting
Low-to-moderate hazard.Read moreShow less
EWG 3 CIR A Antifoaming agentSkin protectingEmollientSkin conditioning Silicone
Panthenol
Antistatic agent, Hair conditioning
Low-hazard ingredient.Read moreShow less
EWG 1 CIR A Antistatic agentHair conditioningSkin conditioning Good for Dry Skin
Sodium Hyaluronate
Skin conditioning, Humectant
Low-hazard ingredient.Read moreShow less
EWG 1 CIR A Skin conditioningHumectant Good for Dry Skin
Allantoin
Skin conditioning, Skin protecting
Low-hazard ingredient.Read moreShow less
EWG 1 CIR A Skin conditioningSkin protectingSoothing Good for Oily SkinGood for Sensitive Skin
Butylene Glycol
Fragrance, Skin conditioning
Low-hazard ingredient.Read moreShow less
EWG 1 CIR A FragranceSkin conditioningSolventViscositydecreasing agentHumectantMaskingViscosity controlling Good for Dry Skin
Alcohol Denat.
Antifoaming agent, Antimicrobial
Causes moisture evaporation - prone to dry out skinRead moreShow less
EWG 4 Antifoaming agentAntimicrobialAstringentMaskingSolventViscosity controlling Bad for Dry SkinBad for Sensitive Skin
Beta-Carotene
Skin conditioning
Low-hazard ingredient.Read moreShow less
EWG 2 Skin conditioning Good for Dry Skin

How to use

How to use

  • 1 Where it fits: Apply after toner and before moisturiser — thinnest to thickest.
  • 2 Morning only: Apply as the last step of your AM routine, after moisturiser, and reapply every ~2 hours of sun exposure.

General guidance from this product's category and active ingredients — always follow the directions on the package.

Trust & honesty

Officially notified as a cosmetic in Malaysia (NPRA). Government registration record.

Effective levels — general guide

The concentrations these actives are typically effective at in research — not a measurement of this product.

Vitamin C (ascorbic) 5–20%

L-ascorbic acid is usually used at 5–20% (around 10–15% is common). Above ~20% adds little and tends to irritate more; it also needs a low pH to work.

ASCORBIC ACID, 3-O-ETHYL ASCORBIC ACID

Niacinamide 2–5% (up to 10%)

Most research uses 2–5%; some formulas go to 10%. Very high levels can cause flushing in sensitive skin.

Niacinamide

INCI lists don't disclose amounts, and we don't claim to know this product's levels — these are the ranges these ingredients are usually effective at, so you can tell a real formula from "fairy-dusting" a marketed active. How we estimate this.

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