The Vitamin C 23 Serum

COSRX Official

The Vitamin C 23 Serum

The Vitamin C 23 Serum

COSRX Official

the-vitamin-c-23-serum

Serum

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Morning or Evening?

Morning
Evening
Both

How often will you use this product?

Everyday
Every other day
Every 3 days
Every 4 days
Every 5 days
Every 6 days
Once a week
Twice a week
On specific days
As needed
On rotation

Notes

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Compatibility Score

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Highlights

WHAT IS IT?

Vitamin C serum

FEATURES

23% pure vitamin C, improves skin tone, reduces wrinkles, targets dull and rough skin

BEST FOR

Sensitive skin

CHECKS

Free of sulfates, parabens

Who Is It For?

What Does It Help With?

Skin Elasticity Skin Tone Wrinkles Dull And Rough Skin

Budget

Mid-range

How To Use

Which routine should it be used in?

Morning
Evening
 
Cleanse
Tone
Eyecare
Serum
Moisturize
Suncare
 

Instructions:

After cleansing, during the serum phase, shake the bottle lightly once or twice from side to side and apply a few drops to the skin. Use fingertips to gently massage and absorb the serum, starting from the inside of the face working towards the edges.

Key Information

Vegan
Cruelty-free
Sensitive-safe
Non-comedogenic
Hypoallergenic
Microbiome-safe
Preservative-free
Eco-friendly
Pregnancy-safe
Oil-free

What COSRX Official Says

Product Description:

Enhances skin elasticity with 23% pure vitamin C. The 23% highly concentrated stabilized pure vitamin C serum improves skin tone, reduces wrinkles, and targets dull and rough skin as a vitamin C booster. This serum is highly effective, and to slowly prevent oxidation, it is divided into two layers with oil on top of the serum, providing a moisturizing finish.

About the Brand:

COSRX has revolutionized Korean skincare with its minimalist, problem-solving approach. Known for high-concentration formulas and clean ingredient lists, this brand focuses on effective solutions for various skin concerns. Experience the perfect balance of science and simplicity with COSRX's targeted treatments that deliver visible results.

Ingredients Overview

Ingredients List

Water, Ascorbic Acid(23%), Propanediol, Dimethicone, Tromethamine, Panthenol, Ethyl Ascorbyl Ether, Squalane, Caffeine, Sodium Chloride, Sodium Hyaluronate, Sodium Sulfite, Disodium EDTA, Glutathione, Adenosine, Acetyl Glucosamine, Gardenia Florida Fruit Extract, Allantoin, Dextrin, Tocotrienols, Tocopherol, Elaeis Guineensis (Palm) Oil, Butylene Glycol, Arginine, Niacinamide, Pentylene Glycol, Alcohol Denat., Helianthus Annuus (Sunflower) Seed Oil, Glycyrrhiza Glabra (Licorice) Root Extract, Methyl Trimethicone, Carthamus Tinctorius (Safflower) Seed Oil, Camellia Japonica Seed Oil, Daucus Carota Sativa (Carrot) Root Extract, Beta-Carotene

Key Ingredients

23% Pure Vitamin C (Ascorbic acid), Super vitamin E (Tocotrienol), Hyaluronic acid, Allantoin

Ingredients Details

Caffeine

Common Name(s): Caffeine,methylxanthine anti-cellulite,antioxidant vasoactive

CAS Number: N/a

DESCRIPTION

What It Does: Stimulates lipolysis in adipocytes by inhibiting phosphodiesterase (preventing camp breakdown), reduces eye puffiness through vasoconstriction of periorbital capillaries, and provides antioxidant dna repair stimulation for photoprotective benefit.

Why It's Used: The only cosmetic active with a well-defined mechanism for anti-cellulite claims โ€” phosphodiesterase inhibition elevating adipocyte camp is the documented biochemical pathway, providing mechanism-based efficacy substantiation superior to most slimming actives.

How It Works: Caffeine inhibits phosphodiesterase (pde3, pde4) preventing camp hydrolysis โ†’ elevated camp activates protein kinase a โ†’ phosphorylates hormone-sensitive lipase โ†’ lipolysis of triglycerides in adipocytes. for eye puffiness: caffeine's adenosine receptor antagonism reduces prostaglandin-mediated capillary dilation in periorbital tissue, reducing fluid accumulation.

Typically Found In: Anti-cellulite,eye creams,antioxidant products

TECHNICAL DETAILS

Primary Category: Active ingredient โ€“ antioxidant

Secondary Functions: Free radical scavenging,anti-aging

Application Areas:

Facial Skincare

Body Care

Hair Care

Beard Care

Color Cosmetics (Makeup)

Dietary/Oral Supplements

Typical Concentration Range: 0.1%โ€“3%

SOURCING & ETHICS

Vegan Status: Yes

Halal Status: Yes

Source Notes: Plant-derived extract or synthetic.

SKIN COMPATIBILITY

Irritancy Rating: 1/5 โ€“ very low

Comedogenicity Rating: 0/5 โ€“ non-comedogenic

Sensitivity Concerns: Non-irritating; well-tolerated.

Safe for Sensitive Skin: Yes

SAFETY & COMPATIBILITY

Safety Profile: Excellent safety profile. ewg score: 1.

Works Well With: Vitamin c,vitamin e,ferulic acid,spf,other antioxidants

Avoid Combining With: No significant incompatibilities

SCIENTIFIC NOTE

Caffeine has one of the highest sc penetration rates of any cosmetic active (logp -0.07, mw 194 da) โ€” the combination of small size and moderate logp providing excellent aqueous solubility with sufficient sc lipid partitioning for effective transdermal delivery to adipose tissue.

Last Verified: Cosing database,caffeine pde inhibitor anti-cellulite lipolysis review

Primary Sources: 2026-03-12

Dimethicone

Common Name(s): Pdms,polydimethylsiloxane,silicone fluid

CAS Number: 9006-65-9

DESCRIPTION

What It Does: Provides silicone-characteristic silky feel and skin protection with adjustable viscosity.

Why It's Used: The benchmark cosmetic silicone โ€“ sets the gold standard for silky application feel, spreadability, and skin protection in virtually all skin care categories.

How It Works: Polydimethylsiloxane chain flexibility provides extremely low surface tension and high spreadability. inert si-o backbone provides chemical stability and excellent skin tolerance. occlusive film formation reduces tewl. higher viscosity grades provide more intense conditioning.

Typically Found In: Moisturizers,foundations,primers,sunscreens โ€“ nearly universal

TECHNICAL DETAILS

Primary Category: Functional ingredient โ€“ polydimethylsiloxane

Secondary Functions: Barrier sealing,softening

Application Areas:

Facial Skincare

Body Care

Hair Care

Beard Care

Color Cosmetics (Makeup)

Dietary/Oral Supplements

Typical Concentration Range: 0.1%โ€“30%

SOURCING & ETHICS

Vegan Status: Yes โ€“ synthetic

Halal Status: Yes

Source Notes: Plant-derived, synthetic or animal-derived. verify source.

SKIN COMPATIBILITY

Irritancy Rating: 1/5 โ€“ very low

Comedogenicity Rating: 1/5 โ€“ low; formulation-dependent

Sensitivity Concerns: Non-irritating.

Safe for Sensitive Skin: Yes

SAFETY & COMPATIBILITY

Safety Profile: Excellent safety profile. ewg score: 1.

Works Well With: Humectants,ceramides,actives as carrier

Avoid Combining With: No significant incompatibilities

SCIENTIFIC NOTE

Dimethicone's exceptional silky feel arises from its very low intermolecular attractive forces (weak van der waals forces due to non-polar methyl groups) that allow silicone chains to slide freely over skin. the coefficient of kinetic friction for pdms against skin (~0.04) is among the lowest of any cosmetic material โ€“ explaining why even small amounts transform product feel.

Last Verified: Cosing database,cir safety assessment

Primary Sources: 2026-03-12

Panthenol

Common Name(s): Provitamin b5,d-panthenol,dl-panthenol,d-pantothenyl alcohol,(r)-2,4-dihydroxy-n-(3-hydroxypropyl)-3,3-dimethylbutanamide

DESCRIPTION

What It Does: Panthenol deeply moisturizes skin and hair, soothes irritation, accelerates wound healing, strengthens the skin barrier, and improves hair elasticity and shine.

Why It's Used: It is used because it is exceptionally versatile, working in both skin and hair formulations. it is gentle enough for sensitive and post-procedure skin, and converts to the active vitamin b5 within the skin.

How It Works: Panthenol penetrates skin and hair, where it is oxidized to pantothenic acid (vitamin b5), a coenzyme a precursor essential to metabolism. in skin, it acts as a humectant and stimulates fibroblast proliferation. in hair, it coats the shaft, improving manageability.

Typically Found In: Moisturizers,serums,toners,after-sun products,wound healing products,shampoos,conditioners,hair masks,beard care

TECHNICAL DETAILS

Primary Category: Active ingredient โ€“ provitamin b5

Secondary Functions: Anti-inflammatory,wound healing,hair conditioning

Application Areas:

Facial Skincare

Body Care

Hair Care

Beard Care

Color Cosmetics (Makeup)

Dietary/Oral Supplements

Typical Concentration Range: 0.5%โ€“5% (typical: 1โ€“3%)

SOURCING & ETHICS

Vegan Status: Yes โ€“ synthetically produced

Halal Status: Yes

Source Notes: Commercially synthesized. both d- and dl-forms used in cosmetics; d-panthenol is the biologically active isomer but dl-panthenol is less expensive and widely used.

SKIN COMPATIBILITY

Irritancy Rating: 1/5 โ€“ very low; one of the most soothing ingredients in cosmetics

Comedogenicity Rating: 0/5 โ€“ non-comedogenic

Sensitivity Concerns: Extremely rare contact allergy; considered one of the safest cosmetic ingredients. suitable for all skin types.

Safe for Sensitive Skin: Yes โ€“ ideal for sensitive, reactive, and post-procedure skin

SAFETY & COMPATIBILITY

Safety Profile: Exceptionally safe. ewg hazard score: 1. no significant concerns for irritation, sensitization, or systemic toxicity. safe during pregnancy.

Works Well With: Hyaluronic acid,ceramides,allantoin,niacinamide,centella asiatica,retinol (reduces irritation),glycerin

Avoid Combining With: No known significant incompatibilities

SCIENTIFIC NOTE

Panthenol has demonstrated wound-healing properties in clinical studies, stimulating fibroblast proliferation and migration. its dual humectant and anti-inflammatory action makes it particularly effective in barrier-repair formulations.

Last Verified: Cosing database,cir safety assessment,ebner et al. (2002) skin pharmacology and applied skin physiology

Primary Sources: 2026-03-12

Propanediol

Common Name(s): 1,3-propanediol,zemea,bio-propanediol

CAS Number: 504-63-2

DESCRIPTION

What It Does: Provides humectant and solvent functionality from sustainable corn-based fermentation.

Why It's Used: Bio-based propylene glycol alternative from renewable corn โ€” propanediol provides equivalent functionality to propylene glycol with sustainable renewable feedstock and superior skin feel.

How It Works: Two oh groups provide humectant water binding. excellent solvent for fragrances, actives, and preservatives. mild antimicrobial from diol structure for preservative system boosting. renew corn fermentation origin (dupont zemea process). better skin feel than propylene glycol โ€” less sticky.

Typically Found In: Virtually all cosmetic categories as pg alternative

TECHNICAL DETAILS

Primary Category: Functional ingredient โ€“ humectant

Secondary Functions: Tewl reduction,skin plumping

Application Areas:

Facial Skincare

Body Care

Hair Care

Beard Care

Color Cosmetics (Makeup)

Dietary/Oral Supplements

Typical Concentration Range: 1%โ€“20%

SOURCING & ETHICS

Vegan Status: Yes โ€“ from corn sugar fermentation

Halal Status: Yes

Source Notes: Synthetic or naturally derived. excellent aqueous solubility.

SKIN COMPATIBILITY

Irritancy Rating: 1/5 โ€“ very low

Comedogenicity Rating: 0/5 โ€“ non-comedogenic

Sensitivity Concerns: Non-irritating; suitable for all skin types.

Safe for Sensitive Skin: Yes

SAFETY & COMPATIBILITY

Safety Profile: Excellent safety profile. ewg score: 1.

Works Well With: Ceramides,emollients,occlusives,glycerin,hyaluronic acid

Avoid Combining With: No significant incompatibilities

SCIENTIFIC NOTE

Propanediol's dupont tate & lyle bio products 'zemea' process ferments corn sugar to 1,3-propanediol using engineered e. coli โ€” one of the first commercially viable bio-fermentation routes to a cosmetic diol previously made only from petroleum. the renewable route produces chemically identical 1,3-propanediol while reducing carbon footprint by approximately 40% vs petrochemical synthesis.

Last Verified: Cosing database,dupont tate & lyle zemea technical data,cir safety assessment

Primary Sources: 2026-03-12