Gentle Vitamin C Custom Serum

Cosmocost

Where to buy Possibly in stock

About this product

The Cosmocost Gentle Vitamin C Custom Serum is a serums, essence, ampoule. Our analysis of its 10 ingredients (6 low-risk) rates it Excellent (100/100). Based on its ingredients, it looks well-suited to oily / acne-prone, dry, and sensitive skin.

Vegan-friendly Reef-safe

Summarised from our ingredient analysis — not brand marketing copy.

At a glance

Type
Serums, Essence, Ampoules
Ingredients
10
Low-risk
6
Fragrance
Fragrance-free
Origin
United States
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 3/1
Good for dry skin
C12-15 Alkyl Benzoate Squalane Caprylic/Capric Triglyceride
Caution for dry skin
Sambucus Nigra Fruit Extract
Oily/Acne-Prone Skin 1/0
Good for oily/acne-prone skin
Sambucus Nigra Fruit Extract
Sensitive Skin 1/1
Good for sensitive skin
Tetrahexyldecyl Ascorbate
Caution for sensitive skin
Caprylic/Capric Triglyceride

Ingredients list

10 total
Lower hazard (1) Higher hazard (1)
All10 Skin Conditioning9 Emollient3 Antioxidant3 Solvent2 Fragrance2 Perfuming2 Skin Protecting1 Chelating1
EWG CIR Ingredient Name & Cosmetic Functions Notes
1
A
Squalane
(Emollient, Hair Conditioning, Refatting, Skin Conditioning)
1
Tetrahexyldecyl Ascorbate
(Antioxidant, Skin Conditioning)
1
Dimethyl Isosorbide
(Solvent, Viscosity Decreasing Agent, Viscosity Controlling)
1
A
C12-15 Alkyl Benzoate
(Skin Conditioning, Emollient, Antimicrobial)
1
A
Caprylic/Capric Triglyceride
(Emollient, Masking, Perfuming, Skin Conditioning, Solvent)
1
Sambucus Nigra Fruit Extract
(Astringent)
glycyrrhiza glabra root extract
(Bleaching, Perfuming, Skin Conditioning, Skin Conditioning Emollient, Smoothing, Soothing)
prunus armeniaca kernel oil
(Fragrance, Skin Conditioning)
TOCOPHEROL
(Antioxidant, Fragrance, Skin Conditioning)
Acetyl Zingerone
(Antioxidant, Chelating, Skin Protecting)

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

Antioxidants
Shields skin from free radical damage.
Vitamin C
Brightens, evens tone, and supports collagen.
Vitamin E
Protects skin and soothes irritation.

Benefits

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

Concerns

No major concerns flagged

Ingredients explained

Squalane
Emollient, Hair conditioning
Low-hazard ingredient.Read moreShow less
EWG 1 CIR A EmollientHair conditioningRefattingSkin conditioning
Tetrahexyldecyl Ascorbate
Antioxidant, Skin conditioning
Low-hazard ingredient.Read moreShow less
EWG 1 AntioxidantSkin conditioning
Dimethyl Isosorbide
Solvent, Viscosity decreasing agent
Low-hazard ingredient.Read moreShow less
EWG 1 SolventViscosity decreasing agentViscosity controlling
C12-15 Alkyl Benzoate
Skin conditioning, Emollient
Low-hazard ingredient.Read moreShow less
EWG 1 CIR A Skin conditioningEmollientAntimicrobial
Caprylic/Capric Triglyceride
Emollient, Masking
Low-hazard ingredient.Read moreShow less
EWG 1 CIR A EmollientMaskingPerfumingSkin conditioningSolvent
Sambucus Nigra Fruit Extract
Astringent
Low-hazard ingredient.Read moreShow less
EWG 1 Astringent
glycyrrhiza glabra root extract
Bleaching, Perfuming
Limited public safety data.Read moreShow less
EWG N/A BleachingPerfumingSkin conditioningSkin conditioning emollientSmoothingSoothing
prunus armeniaca kernel oil
Fragrance, Skin conditioning
Limited public safety data.Read moreShow less
EWG N/A FragranceSkin conditioning
TOCOPHEROL
Antioxidant, Fragrance
Limited public safety data.Read moreShow less
EWG N/A AntioxidantFragranceSkin conditioning
Acetyl Zingerone
Antioxidant, Chelating
Limited public safety data.Read moreShow less
EWG N/A AntioxidantChelatingSkin protecting
No flagged concerns — nice!

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.

Tetrahexyldecyl Ascorbate

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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