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Merit Beauty Great Skin Instant Glow Serum Versus COSRX The Niacinamide 15 Serum

Serum
Serum
American Brand United States
Korean Brand South Korea

Updated on June 28, 2024

Overview

What they are

These products are both cruelty-free, fungal acne (malassezia) safe, and reef safe serums. They have a total of 8 ingredients in common

Cool Features

They both contain niacinamide and Vitamin E

Suited For

They're both likely to be good for fighting acne, brightening skin, oily skin, reducing pores, scar healing and dark spots

Free From

They both do not contain any harsh alcohols, common allergens, fragrances, oils, parabens, silicones or sulfates

We independently verify ingredients, and our claims are backed by peer-reviewed research. Spot a product that needs an update? Let us know.

Ingredient Info

Click any item below to learn more and see relevant ingredients

At a glance

Click on any of the items below to learn more

Notable Ingredients

Benefits

Concerns

Notable Ingredients

Benefits

Ingredients Side-by-side

found in both products
Great Skin Instant Glow Serum
Water Skin Conditioning, Solvent

Water. It's the most common cosmetic ingredient of all. You'll usually see it at the top of ingredient lists, meaning that it makes up the largest part of the product.

Propanediol Solvent

Propanediol helps absorb ingredients into your skin, boosting their benefits. It can act as an emollient, making your skin softer. Propanediol can help products last longer by boosting the properties of preservatives within the formulation.

Caprylic/Capric Triglyceride Masking, Skin Conditioning

Caprylic/Capric Triglyceride is an emollient, solvent, and texture enhancer. It is considered a skin-softener by helping the skin prevent moisture loss.

Isononyl Isononanoate Emollient, Skin Conditioning

Isononyl Isononanoate is a synthetic skin-conditioner and texture enhancer. It is created from nonanoic acid, a fatty acid found in cocoa and lavender oil.

1,2-Hexanediol Skin Conditioning, Solvent

1,2-Hexanediol is a multi-tasker ingredient. It acts as a preservative to increase shelf-life and can aid other preservatives in preventing microbe growth. 1,2-Hexanediol also helps the skin retain moisture as a humectant.

Niacinamide Smoothing
Niacinamide IconGood for Oily Skin IconHelps reduce Skin Redness IconGood for Minimizing Pores IconGood for Dark Spots IconHelps fight Acne IconHelps brighten skin Icon
NiacinamideNiacinamide Icon 6 Benefits

Niacinamide has emerged as an all-star ingredient due to its many benefits.

Sodium Hyaluronate Humectant, Skin Conditioning
0 / 0 Hyaluronic Acid Icon
Hyaluronic AcidHyaluronic Acid Icon

Sodium Hyaluronate is hyaluronic acid's salt form. It is commonly derived from the sodium salt of hyaluronic acid.

0 Com. / 0 Irr.
Sodium Hyaluronate Crosspolymer Humectant, Skin Conditioning
Hyaluronic Acid Icon
Hyaluronic AcidHyaluronic Acid Icon

Sodium Hyaluronate Crosspolymer is a type of hyaluronic acid. In fact, it is modified version of hyaluronic acid.

Hydrolyzed Sodium Hyaluronate Skin Conditioning

This ingredient is created by putting sodium hyaluronate through hydrolysis.

Sodium Acetylated Hyaluronate Humectant
Hyaluronic Acid Icon
Hyaluronic AcidHyaluronic Acid Icon

Sodium Acetylated Hyaluronate is a type of Hyaluronic Acid.

Coptis Japonica Root Extract Skin Conditioning

We don't have a description for Coptis Japonica Root Extract.

Theobroma Cacao Seed Extract Antioxidant
Antioxidant Icon
AntioxidantAntioxidant Icon

Theobroma Cacao Seed Extract comes from the Theobroma cacoa, or Cacao tree. Cacao trees are native to tropical landscapes.

Tocopherol Antioxidant, Masking, Skin Conditioning
0-3 / 0-3 Vitamin E IconAntioxidant IconHelps hydrate Dry Skin IconHelps with Anti-Aging IconGood for Scar Healing IconHelps brighten skin IconMay cause irritation Icon
Vitamin EVitamin E Icon AntioxidantAntioxidant Icon 4 Benefits May cause irritationMay cause irritation Icon

Tocopherol (also known as Vitamin E) is a common antioxidant used to help protect the skin from free-radicals and strengthen the skin barrier. It's also fat soluble - this means our skin is great at absorbing it.

0-3 Com. / 0-3 Irr.
Butylene Glycol Humectant, Masking, Skin Conditioning
1 / 0

Butylene Glycol (or BG) is used within cosmetic products for a few different reasons:

1 Com. / 0 Irr.
Pentylene Glycol Skin Conditioning, Solvent

Pentylene glycol is typically used within a product to thicken it. It also adds a smooth, soft, and moisturizing feel to the product. It is naturally found in plants such as sugar beets.

Ethylhexylglycerin Skin Conditioning

Ethylhexylglycerin (we can't pronounce this either) is commonly used as a preservative and skin softener. It is derived from glyceryl.

Citric Acid Buffering, Masking
AHA IconGood for Skin Texture IconGood for Minimizing Pores IconGood for Scar Healing IconHelps brighten skin IconMay cause irritation IconMay worsen Rosacea Icon
AHAAHA Icon 4 Benefits 2 Concerns

Citric Acid is an AHA derived from citrus fruits (think oranges, lemons, and limes!).

Disliked Full details ->
Sodium Citrate Buffering, Masking

Sodium Citrate is the sodium salts of citric acid. In skincare, it is used to alter pH levels and acts as a preservative.

Dextrin Absorbent

Dextrin is used to thicken a product and helps bind ingredients together. It is created from starch and glycogen.

Trisodium Ethylenediamine Disuccinate

Trisodium Ethylenediamine Disuccinate is used to help stabilize a product.

The Niacinamide 15 Serum
Water Skin Conditioning, Solvent

Water. It's the most common cosmetic ingredient of all. You'll usually see it at the top of ingredient lists, meaning that it makes up the largest part of the product.

Pentylene Glycol Skin Conditioning, Solvent

Pentylene glycol is typically used within a product to thicken it. It also adds a smooth, soft, and moisturizing feel to the product. It is naturally found in plants such as sugar beets.

Niacinamide Smoothing
Niacinamide IconGood for Oily Skin IconHelps reduce Skin Redness IconGood for Minimizing Pores IconGood for Dark Spots IconHelps fight Acne IconHelps brighten skin Icon
NiacinamideNiacinamide Icon 6 Benefits

Niacinamide has emerged as an all-star ingredient due to its many benefits.

Butylene Glycol Humectant, Masking, Skin Conditioning
1 / 0

Butylene Glycol (or BG) is used within cosmetic products for a few different reasons:

1 Com. / 0 Irr.
Acetyl Glucosamine Skin Conditioning
Vitamin C Icon
Vitamin CVitamin C Icon

Acetyl Glucosamine is an antioxidant and humectant. It is a form of Vitamin C.

1,2-Hexanediol Skin Conditioning, Solvent

1,2-Hexanediol is a multi-tasker ingredient. It acts as a preservative to increase shelf-life and can aid other preservatives in preventing microbe growth. 1,2-Hexanediol also helps the skin retain moisture as a humectant.

Zinc PCA Humectant, Skin Conditioning
Good for Scar Healing IconHelps fight Acne Icon
2 Benefits

Zinc PCA (or "zinc salt") differs slightly from zinc itself. PCA stands for pyrrolidone carboxylic acid. However, Zinc PCA comes from zinc.

Trehalose Humectant, Moisturising

Trehalose is a disaccharide made of two glucose molecules (glucose is sugar!). Trehalose is used to help moisturize skin. It also has antioxidant properties.

Xanthan Gum Emulsifying, Emulsion Stabilising, Gel Forming

Xanthan gum is used as a stabilizer and thickener within cosmetic products. It helps give products a sticky, thick feeling - preventing them from being too runny.

Disliked Full details ->
Pullulan

We don't have a description for Pullulan.

Allantoin Skin Conditioning, Skin Protecting, Soothing
0 / 0 Helps reduce Skin Redness IconHelps reduce irritation IconGood for Scar Healing Icon
3 Benefits

Allantoin plays a role in soothing and moisturizing the skin. Because of this, it is often added to products with strong active ingredients.

0 Com. / 0 Irr.
Ethylhexylglycerin Skin Conditioning

Ethylhexylglycerin (we can't pronounce this either) is commonly used as a preservative and skin softener. It is derived from glyceryl.

Sodium Phytate

Sodium Phytate is the synthetic salt form of phytic acid. Phytic acid is an antioxidant and can be found in plant seeds.

Citric Acid Buffering, Masking
AHA IconGood for Skin Texture IconGood for Minimizing Pores IconGood for Scar Healing IconHelps brighten skin IconMay cause irritation IconMay worsen Rosacea Icon
AHAAHA Icon 4 Benefits 2 Concerns

Citric Acid is an AHA derived from citrus fruits (think oranges, lemons, and limes!).

Disliked Full details ->
Tocopherol Antioxidant, Masking, Skin Conditioning
0-3 / 0-3 Vitamin E IconAntioxidant IconHelps hydrate Dry Skin IconHelps with Anti-Aging IconGood for Scar Healing IconHelps brighten skin IconMay cause irritation Icon
Vitamin EVitamin E Icon AntioxidantAntioxidant Icon 4 Benefits May cause irritationMay cause irritation Icon

Tocopherol (also known as Vitamin E) is a common antioxidant used to help protect the skin from free-radicals and strengthen the skin barrier. It's also fat soluble - this means our skin is great at absorbing it.

0-3 Com. / 0-3 Irr.

Ingredients Explained

These ingredients are found in both products.

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

Skin Conditioning, Solvent
Loved

Water. It's the most common cosmetic ingredient of all. You'll usually see it at the top of ingredient lists, meaning that it makes up the largest part of the product.

So why is it so popular? Water most often acts as a solvent - this means that it helps dissolve other ingredients into the formulation.

You'll also recognize water as that liquid we all need to stay alive. If you see this, drink a glass of water. Stay hydrated!

Learn more about Water
Skin Conditioning, Solvent
Mixed

1,2-Hexanediol is a multi-tasker ingredient. It acts as a preservative to increase shelf-life and can aid other preservatives in preventing microbe growth. 1,2-Hexanediol also helps the skin retain moisture as a humectant.

In products that are water-based, this ingredient can help stabilize perfumes and fragrances. It can also help make the texture of products softer and more smooth.

Smoothing
Loved

Niacinamide has emerged as an all-star ingredient due to its many benefits.

It is known to treat acne by reducing inflammation. It also helps fade dark-spots and strengthen the skin by promoting the growth of the ceramide barrier.

Other benefits include smoothing wrinkles and minimizing redness.

The cherry on top? Niacinamide can also help build keratin, a protein that keeps skin firm.

When incorporating niacinamide into your routine, look out for concentration amounts. Typically, 5% niacinamide provides benefits such as fading dark spots. However, if you have sensitive skin, it is better to begin with a smaller concentration.

Niacinamide can be mixed with other ingredients to boost benefits. For instance, it has shown to be effective when used with copper, folic acid, and zinc to treat acne.

Learn more about Niacinamide
Antioxidant, Masking, Skin Conditioning
Liked

Tocopherol (also known as Vitamin E) is a common antioxidant used to help protect the skin from free-radicals and strengthen the skin barrier. It's also fat soluble - this means our skin is great at absorbing it.

Vitamin E also helps keep your natural skin lipids healthy. Your lipid skin barrier naturally consists of lipids, ceramides, and fatty acids. Vitamin E offers extra protection for your skin’s lipid barrier, keeping your skin healthy and nourished.

Another benefit is a bit of UV protection. Vitamin E helps reduce the damage caused by UVB rays. (It should not replace your sunscreen). Combining it with Vitamin C can decrease sunburned cells and hyperpigmentation after UV exposure.

You might have noticed Vitamin E + C often paired together. This is because it is great at stabilizing Vitamin C. Using the two together helps increase the effectiveness of both ingredients.

There are often claims that Vitamin E can reduce/prevent scarring, but these claims haven't been confirmed by scientific research.

Learn more about Tocopherol
Humectant, Masking, Skin Conditioning
Mixed

Butylene Glycol (or BG) is used within cosmetic products for a few different reasons:

  • It is a solvent, meaning that it helps to dissolve other ingredients. This also enhances the absorption of the product into one's skin.
  • It is a humectant, which means that it helps attract moisture into the skin.
  • It helps improve product application.

Overall, Butylene Glycol is a safe and well-rounded ingredient. It is unlikely to irritate skin, and works well with pretty much all other ingredients.

Skin Conditioning, Solvent
Mixed

Pentylene glycol is typically used within a product to thicken it. It also adds a smooth, soft, and moisturizing feel to the product. It is naturally found in plants such as sugar beets.

The hydrophilic trait of Pentylene Glycol makes it a humectant. As a humectant, Pentylene Glycol helps draw moisture from the air to your skin. This can help keep your skin hydrated.

This property also makes Pentylene Glycol a great texture enhancer. It can help thicken or emulsify a product. Emulsifiers help stabilize a product. It does this by preventing certain ingredients from separating.

Pentylene Glycol also acts as a mild preservative and helps to keep a product microbe-free.

Some people may experience mild eye and skin irritation from Pentylene Glycol. We always recommend speaking with a professional about using this ingredient in your routine.

Pentylene Glycol has a low molecular weight and is part of the 1,2-glycol family.

Learn more about Pentylene Glycol
Skin Conditioning
Mixed

Ethylhexylglycerin (we can't pronounce this either) is commonly used as a preservative and skin softener. It is derived from glyceryl.

You might see Ethylhexylglycerin often paired with other preservatives such as phenoxyethanol. Ethylhexylglycerin has been found to increase the effectiveness of these other preservatives.

Buffering, Masking
Disliked

Citric Acid is an AHA derived from citrus fruits (think oranges, lemons, and limes!).

As an AHA, Citric Acid removes the top layer of skin cells from the newer layer of skin underneath. This helps skin to remove dark spots and even out skin tone.

If you spot Citric Acid near the end of an ingredient list, it's likely there as a pH adjuster rather than an active ingredient.

Read more about some other popular AHA's here:

Learn more about Citric Acid

Ingredient Ratings

Here's what our community thinks of the ingredients in these products.

Great Skin Instant Glow Serum
12
7
1
liked
mixed
disliked
not rated
The Niacinamide 15 Serum
9
4
2
liked
mixed
disliked
not rated

When to use

42 Routines
76% use in am
24% use in pm
95% use every day
When to use See routines that use it ->
309 Routines
45% use in am
55% use in pm
92% use every day
When to use See routines that use it ->

Reviews

Here's what our community thinks

Merit Beauty Great Skin Instant Glow Serum 20 ingredients

5.0 /5
from 1 rating
a.b.c.d.e's avatar

a.b.c.d.e

12 months ago · Unsure Skin
Review

Makes u SO glowy in the morning as and helps skin feel moisturized

COSRX The Niacinamide 15 Serum 15 ingredients

3.5 /5
from 4 ratings
Broke Me Out (1) Irritating (1)
ChienYun_CY's avatar

ChienYun_CY

10 months ago · Combination Skin
Review

HG acne scar serum
Initially, this serum had helped fade away most of my old acne scars. After while, I thought it didn't do anything more for my...

HG acne scar serum
Initially, this serum had helped fade away most of my old acne scars. After while, I thought it didn't do anything more for my new acne growth. So I ditched this serum for about 3 months and tried other new niacinamide products. I REGRET it. Soon after, I got more and more whiteheads and acne. My skin texture becomes uneven and dry. The new acne scars couldn't fade away at all. I decided to repurchase this serum, and almost immediately, my scars cleared and had reduced inflammation on new cystic acne. It also helped to control sebum production and I have lesser acne growth. One of the products I cannot live without.

lias's avatar

Lia S

6 days ago · Normal Skin
Review

Too irritating for me, broke me out so bad