COSRX The Vitamin C 23 Serum Versus The INKEY List Vitamin C Serum

COSRX The Vitamin C 23 Serum Versus The INKEY List Vitamin C Serum

This brightening serum is formulated around Ascorbic Acid and 3-O-Ethyl Ascorbic Acid to brighten dull-looking skin and fade the look of dark spots.

This brightening serum is formulated around Ascorbic Acid to brighten dull-looking skin and soften the look of wrinkles.

What's inside

Key Ingredients

Benefits

Concerns

No concerns

Ingredients Side-by-side

Water

Ascorbic Acid 23%

Propanediol

Dimethicone

Tromethamine

Panthenol

3-O-Ethyl Ascorbic Acid

Squalane

Caffeine

Sodium Chloride

Sodium Hyaluronate

Sodium Sulfite

Disodium EDTA

Glutathione

Adenosine

Acetyl Glucosamine

Gardenia Florida Fruit Extract

Allantoin

Dextrin

Tocotrienols

Tocopherol

Elaeis Guineensis Oil

Butylene Glycol

Arginine

Niacinamide

Pentylene Glycol

Alcohol Denat.

Helianthus Annuus Seed Oil

Glycyrrhiza Glabra Root Extract

Methyl Trimethicone

Carthamus Tinctorius Seed Oil

Camellia Japonica Seed Oil

Daucus Carota Sativa Root Extract

Beta-Carotene

Water, Ascorbic Acid 23%, Propanediol, Dimethicone, Tromethamine, Panthenol, 3-O-Ethyl Ascorbic Acid, Squalane, Caffeine, Sodium Chloride, Sodium Hyaluronate, Sodium Sulfite, Disodium EDTA, Glutathione, Adenosine, Acetyl Glucosamine, Gardenia Florida Fruit Extract, Allantoin, Dextrin, Tocotrienols, Tocopherol, Elaeis Guineensis Oil, Butylene Glycol, Arginine, Niacinamide, Pentylene Glycol, Alcohol Denat., Helianthus Annuus Seed Oil, Glycyrrhiza Glabra Root Extract, Methyl Trimethicone, Carthamus Tinctorius Seed Oil, Camellia Japonica Seed Oil, Daucus Carota Sativa Root Extract, Beta-Carotene

Ascorbic Acid 30%

Polysilicone-11

PEG-10 Dimethicone

Dimethicone, Ascorbic Acid 30%, Polysilicone-11, PEG-10 Dimethicone

Reviews

Alternatives

Ingredients Explained

These ingredients are found in both products.

Ingredients higher up in an ingredient list are typically present in a larger amount.

Ascorbic Acid is is pure Vitamin C and is the biologically active form used directly by skin.

Not only is vitamin C great for your overall health and immune system, but it also has plenty of benefits for your skin. It is best supported by academic literature for:

Topical vitamin C has been shown to help neutralize oxidative stress from UV and pollution, helping to improve photoaging and hyperpigmentation when used consistently.

One clinical study found that using 5% topical vitamin C for six months improved signs of photodamaged skin, both on the surface and in the deeper structural layers of the skin.

While vitamin C doesn’t replace sunscreen, studies show it can boost photoprotection when combined with Vitamin E and ferulic acid. These two ingredients help improve stability and protective effects.

The big downside of this ingredient is formulation difficulty. Vitamin C is prone to oxidation and doesn't penetrate the skin unless formulated correctly. Research found that vitamin C absorbs into the skin best at a low pH (< 3.5) with about 20% being the upper limit for effective absorption.

Skin levels can saturate after repeated application; this means your skin won’t keep absorbing more once it’s full of vitamin C. This is why more isn’t always better with vitamin C and why very high concentrations don’t necessarily give extra benefits.

Ascorbic acid generally works well with many skincare ingredients but can be irritating when combined with other active ingredients. Strong oxidizing acne treatments like benzoyl peroxide can reduce the effectiveness of vitamin C if they are used at the same time; they are often recommended for use at different times of day.

Read more about other types of Vitamin C:

Foods rich with vitamin C include oranges, strawberries, broccoli, bell peppers, and more. When consuming Vitamin C, your skin receives a portion of the nutrients.

Dimethicone is a type of synthetic silicone created from natural materials such as quartz. It is also known as polydimethylsiloxane.

What it does:

Dimethicone comes in different viscosities:

Depending on the viscosity, dimethicone has different properties.

Ingredients lists don't always show which type is used, so we recommend reaching out to the brand if you have questions about the viscosity.

This ingredient is unlikely to cause irritation because it does not get absorbed into skin. However, people with silicone allergies should be careful about using this ingredient.

Note: Dimethicone may contribute to pilling. This is because it is not oil or water soluble, so pilling may occur when layered with products. When mixed with heavy oils in a formula, the outcome is also quite greasy.

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