5% Vitamin C Serum

cos.kim

Where to buy Possibly in stock

About this product

The cos.kim 5% Vitamin C Serum is a serums, essence, ampoule. Our analysis of its 13 ingredients (9 low-risk) rates it Excellent (97/100). Based on its ingredients, it looks well-suited to sensitive skin.

Vegan-friendly Reef-safe

Summarised from our ingredient analysis — not brand marketing copy.

At a glance

Type
Serums, Essence, Ampoules
Ingredients
13
Low-risk
9
Fragrance
Fragrance-free
Origin
Türkiye
Data updated
Jun 2026

The evidence

Quick Product Notes

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

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 2/3
Good for dry skin
Glycerin Hyaluronic Acid
Caution for dry skin
Xanthan Gum Glycerin Polysorbate 20
Oily/Acne-Prone Skin No data
Sensitive Skin 2/2
Good for sensitive skin
Glycerin Allantoin
Caution for sensitive skin
Glycerin Phenoxyethanol

Ingredients list

13 total
Lower hazard (1) Higher hazard (4)
All13 Skin Conditioning12 Fragrance4 Skin Protecting3 Humectant3 Viscosity Increasing Agent2 Viscosity Controlling2 Hair Conditioning2 Emulsion Stabilising2
EWG CIR Ingredient Name & Cosmetic Functions Notes
1
Water
(Solvent)
3-O-ETHYL ASCORBIC ACID
(Skin Conditioning)
1
A
Niacinamide
(Hair Conditioning, Skin Conditioning, Smoothing)
rosmarinus officinalis leaf extract
(Antimicrobial, Fragrance, Skin Conditioning)
Citrus Limon Fruit Extract
(Fragrance, Skin Conditioning)
1
A
Hyaluronic Acid
(Skin Conditioning, Viscosity Increasing Agent, Antistatic Agent, Humectant, Moisturising)
3
B
Polysorbate 20
(Emulsifying, Surfactant)
Fungal Acne
Fungal Acne Trigger
1
A
Ethylhexylglycerin
(Deodorant, Skin Conditioning)
4
A
Phenoxyethanol
(Fragrance, Preservative)
Paraben
Paraben
2
A
Glycerin
(Denaturant, Fragrance, Hair Conditioning, Humectant, Oral Care Agent, Oral Health Care Drug, Skin Protecting, Viscosity Decreasing Agent, Perfuming, Solvent)
Good for Dry Skin
Good for Dry Skin
Fungal Acne
Fungal Acne Trigger
1
A
Xanthan Gum
(Binding Agent, Emulsion Stabilising, Skin Conditioning, Surfactant Emulsifying Agent, Viscosity Increasing Agent, Binding, Gel Forming, Viscosity Controlling)
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
Disodium EDTA
(Chelating Agent, Viscosity Controlling)

My Ingredient Notes

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

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No close formula match yet — browse other products like this

Key ingredients

Vitamin C
Brightens, evens tone, and supports collagen.
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.
Redness ReducingSoothes visible redness and calms irritation.
Anti-AgingSoftens lines and helps skin look youthful.
BrighteningRestores radiance to dull, tired skin.
Reduces IrritationEases discomfort and supports skin resilience.
Reduces Large PoresMinimizes the look of enlarged pores.
Scar HealingImproves the look of marks and scars.

Concerns

Contains paraben
Not fungal acne (malassezia) safe
May not suit dry skin

Ingredients explained

Water
Solvent
Low-hazard ingredient.Read moreShow less
EWG 1 Solvent
3-O-ETHYL ASCORBIC ACID
Skin conditioning
Limited public safety data.Read moreShow less
EWG N/A Skin conditioning
Niacinamide
Hair conditioning, Skin conditioning
Low-hazard ingredient.Read moreShow less
EWG 1 CIR A Hair conditioningSkin conditioningSmoothing
rosmarinus officinalis leaf extract
Antimicrobial, Fragrance
Limited public safety data.Read moreShow less
EWG N/A AntimicrobialFragranceSkin conditioning
Citrus Limon Fruit Extract
Fragrance, Skin conditioning
Limited public safety data.Read moreShow less
EWG N/A FragranceSkin conditioning
Hyaluronic Acid
Skin conditioning, Viscosity increasing agent
Low-hazard ingredient.Read moreShow less
EWG 1 CIR A Skin conditioningViscosity increasing agentAntistatic agentHumectantMoisturising
Ethylhexylglycerin
Deodorant, Skin conditioning
Low-hazard ingredient.Read moreShow less
EWG 1 CIR A DeodorantSkin conditioning
Xanthan Gum
Binding agent, Emulsion stabilising
Low-hazard ingredient.Read moreShow less
EWG 1 CIR A Binding agentEmulsion stabilisingSkin conditioningSurfactant -emulsifying agentViscosity increasing agentBindingGel formingViscosity controlling
Disodium EDTA
Chelating agent, Viscosity controlling
Low-hazard ingredient.Read moreShow less
EWG 1 CIR A Chelating agentViscosity controlling
Polysorbate 20
Emulsifying, Surfactant
Low-to-moderate hazard.Read moreShow less
EWG 3 CIR B EmulsifyingSurfactant Fungal-acne trigger
Phenoxyethanol
Fragrance, Preservative
Low-to-moderate hazard.Read moreShow less
EWG 4 CIR A FragrancePreservative Paraben
Glycerin
Denaturant, Fragrance
Low-hazard ingredient.Read moreShow less
EWG 2 CIR A DenaturantFragranceHair conditioningHumectantOral care agentOral health care drugSkin protectingViscosity decreasing agentPerfumingSolvent Good for Dry SkinFungal-acne trigger
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

How to use

How to use

  • 1 Where it fits: Apply after toner and before moisturiser — thinnest to thickest.
  • 2 Morning works well: Antioxidants like vitamin C pair well with daytime use under sunscreen.

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

Trust & honesty

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.

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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