Versus

COSRX The Vitamin C 13 Serum Versus Numbuzin No.5 Vitamin Concentrated Serum

Serum
Serum
Korean Brand South Korea
Korean Brand South Korea

Updated on April 08, 2025

Overview

What they are

These products are both cruelty-free and reef safe serums. They have a total of 14 ingredients in common

Cool Features

They both contain hyaluronic acid, niacinamide, Vitamin C and Vitamin E

Suited For

They're both likely to be good for fighting acne, anti aging, dry skin, brightening skin, sensitive skin, oily skin, reducing pores, scar healing, dark spots and better texture

Free From

They both do not contain any harsh alcohols, common allergens, 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

What's inside (and what isn't)

What's inside (and what isn't)

At a glance

Click on any of the items below to learn more

Key Ingredients

Benefits

Key Ingredients

Benefits

Concerns

Ingredients Side-by-side

found in both products
No.5 Vitamin Concentrated Serum

Water

Skin Conditioning

Butylene Glycol

Humectant
1 / 0 Helps hydrate Dry Skin Icon

Niacinamide

Smoothing
Niacinamide IconGood for Oily Skin IconHelps reduce Skin Redness IconHelps reduce irritation IconGood for Minimizing Pores IconHelps with Anti-Aging IconGood for Dark Spots IconGood for Scar Healing IconHelps fight Acne IconHelps brighten skin Icon

Panthenol

Skin Conditioning
0 / 0 Helps hydrate Dry Skin IconHelps reduce Skin Redness IconHelps reduce irritation IconGood for Scar Healing Icon

Tranexamic Acid

Astringent
Helps reduce irritation IconGood for Dark Spots IconGood for Scar Healing Icon

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

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
Antioxidant, Buffering, Masking

Ascorbic Acid is is pure Vitamin C. This form makes up the largest amount of vitamin C found naturally in our skin.

Not only is vitamin C great for your overall health and immune system, it also has plenty of benefits on your skin.

Vitamin C is best used for brightening skin. It improves dark spots, acne scars, and hyperpigmentation. This is because it blocks the process of skin darkening when exposed to UV.

Remember: Vitamin C should not replace sunscreen!

Your skin uses vitamin C to build collagen. Collagen is one key component in having a strong skin barrier and plump skin. Vitamin C also plays a role in regulating collagen, thus making it effective in improving wrinkles and fine lines.

Ascorbic acid shows potent antioxidant activity. As an antioxidant, it helps fight free-radicals. Free-radicals are molecules that may damage your skin cells. These antioxidants also protect skin against UV damage.

The best formulations include Vitamin E and/or ferulic acid. These two ingredients help stabilize and provide a boost in the benefits of ascorbic acid. This is because ascorbic acid becomes unstable when exposed to UV and air. In fact, you can tell your ascorbic acid has oxidized when it turns an orange-yellow color.

Ascorbic acid is generally compatible with other ingredients. However, using ascorbic acid with other active ingredients might cause irritation. Two ingredients: copper ions and benzoyl peroxide, will inactivate ascorbic acid completely.

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.

Learn more about Ascorbic Acid
Humectant, Masking, Skin Conditioning

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

Overall, Butylene Glycol is a safe and well-rounded ingredient that works well with other ingredients.

Though this ingredient works well with most skin types, some people with sensitive skin may experience a reaction such as allergic rashes, closed comedones, or itchiness.

Learn more about Butylene Glycol
Buffering, Masking

Tromethamine helps balance the pH and improve the texture of a product. It is synthetically created.

As an emulsifier, Tromethamine prevents oil and water ingredients from separating. This helps stabilize the product and elongate a product's shelf life. Tromethamine also makes a product thicker.

Tromethamine helps balance the pH level of a product. Normal pH level of skin is slightly acidic (~4.75-5.5). The acidity of our skin is maintained by our glands and skin biome. Being slightly acidic allows our skin to create an "acid mantle". This acid mantle is a thin barrier that protects our skin from bacteria and contaminants.

Oral Tromethanmine is an anti-inflammatory drug but plays the role of masking, adding fragrance, and/or balancing pH in skincare.

1,3-Propanediol, 2-amino-2-(hydroxymethyl)-

Learn more about Tromethamine
Skin Conditioning

You might know this ingredient as Ethyl Ascorbic Acid, a more stable version of ascorbic acid.

Like other types of vitamin C, this ingredient has many benefits including reducing wrinkles, skin soothing, dark spot fading, and fighting against free radicals.

3-O-Ethyl Ascorbic Acid interferes with the process of skin darkening, helping to reduce hyperpigmentation. It also encourages the skin to produce more collagen.

Once applied, 3-O-Ethyl Ascorbic Acid is converted to Vitamin C deeper in the skin's layers. This process is slow but makes this ingredient more tolerable for skin.

The optimum pH range for this ingredient is 4 - 5.5

Learn more about 3-O-Ethyl Ascorbic Acid
Skin Conditioning

Panthenol is a common ingredient that helps hydrate and soothe the skin. It is found naturally in our skin and hair.

There are two forms of panthenol: D and L.

D-panthenol is also known as dexpanthenol. Most cosmetics use dexpanthenol or a mixture of D and L-panthenol.

Panthenol is famous due to its ability to go deeper into the skin's layers. Using this ingredient has numerous pros (and no cons):

Like hyaluronic acid, panthenol is a humectant. Humectants are able to bind and hold large amounts of water to keep skin hydrated.

This ingredient works well for wound healing. It works by increasing tissue in the wound and helps close open wounds.

Once oxidized, panthenol converts to pantothenic acid. Panthothenic acid is found in all living cells.

This ingredient is also referred to as pro-vitamin B5.

Learn more about Panthenol
Humectant, Skin Conditioning

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

Like hyaluronic acid, it is great at holding water and acts as a humectant. This makes it a great skin hydrating ingredient.

Sodium Hyaluronate is naturally occurring in our bodies and is mostly found in eye fluid and joints.

These are some other common types of Hyaluronic Acid:

Learn more about Sodium Hyaluronate

Disodium EDTA plays a role in making products more stable by aiding other preservatives.

It is a chelating agent, meaning it neutralizes metal ions that may be found in a product.

Disodium EDTA is a salt of edetic acid and is found to be safe in cosmetic ingredients.

Learn more about Disodium EDTA

Glutathione is an antioxidant naturally found in our bodies. It is made up of three amino acids: glycine, cysteine, and glutamic acid.

As an antioxidant, it prevents oxidative damage to parts of our cell.

While glutathione is said to help with fading dark spots, the results from research are inconclusive. Further studies are needed. With that said, gluthatione has been shown to protect our skin from UV-B induced damage.

This ingredient is naturally occurring in plants, animals, fungi, and some bacteria.

Learn more about Glutathione
Skin Conditioning

Adenosine is in every living organism. It is one of four components in nucleic acids that helps store our DNA.

Adenosine has many benefits when used. These benefits include hydrating the skin, smoothing skin, and reducing wrinkles. Once applied, adenosine increases collagen production. It also helps with improving firmness and tissue repair.

Studies have found adenosine may also help with wound healing.

In skincare products, Adenosine is usually derived from yeast.

Learn more about Adenosine
Skin Conditioning, Skin Protecting, Soothing

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

Some studies have shown this ingredient can promote wound healing with higher concentrations.

Allantoin is derived from the comfrey plant but produced synthetically for cosmetic products to ensure purity.

Learn more about Allantoin
Antioxidant, Masking, Skin Conditioning

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
Smoothing

Niacinamide is a multitasking form of vitamin B3 that strengthens the skin barrier, reduces pores and dark spots, regulates oil, and improves signs of aging.

And the best part? It's gentle and well-tolerated by most skin types, including sensitive and reactive skin.

You might have heard of "niacin flush", or the reddening of skin that causes itchiness. Niacinamide has not been found to cause this.

In very rare cases, some individuals may not be able to tolerate niacinamide at all or experience an allergic reaction to it.

If you are experiencing flaking, irritation, and dryness with this ingredient, be sure to double check all your products as this ingredient can be found in all categories of skincare.

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.

When you apply niacinamide to your skin, your body converts it into nicotinamide adenine dinucleotide (NAD). NAD is an essential coenzyme that is already found in your cells as "fuel" and powers countless biological processes.

In your skin, NAD helps repair cell damage, produce new healthy cells, support collagen production, strengthen the skin barrier, and fight environmental stressors (like UV and pollution).

Our natural NAD levels start to decline with age, leading to slower skin repair, visible aging, and a weaker skin barrier. By providing your skin niacinamide, you're recharging your skin's NAD levels. This leads to stronger, healthier, and younger looking skin.

Another name for vitamin B3 is nicotinamide. This vitamin is water-soluble and our bodies don't store it. We obtain Vitamin B3 from either food or skincare. Meat, fish, wheat, yeast, and leafy greens contain vitamin B3.

The type of niacinamide used in skincare is synthetically created.

Learn more about Niacinamide
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.

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 also help thicken or stabilize a product.

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

When to use

236 Routines
81% use in am
19% use in pm
90% use every day
When to use See routines that use it ->
966 Routines
67% use in am
33% use in pm
89% use every day
When to use See routines that use it ->

Reviews

Here's what our community thinks

COSRX The Vitamin C 13 Serum 25 ingredients

The Vitamin C 13 Serum hasn't been rated yet.
Rate it now

Numbuzin No.5 Vitamin Concentrated Serum 47 ingredients

3.4 /5
from 34 ratings
No Scent (14) Hydrating (13) Broke Me Out (12)
ThomasvV's avatar

Thomas VV

5 months ago
Review

This serum is one of the best all-round anti-oxidant and dark spot serums containing:
- vitamin c
- Glutathion!!
- 5% niacinamide
- Q10
- Alpha Arbutin
(Unfortunately they removed TXA)

Skin type: combi acne prone

This is not just a dark spot serum, its a perfect anti-oxidant serum in the morning. Glutathion is a killer ingredient and the concentration of Vit C is low.

My acne Show more

#great value
#hydrating
#absorbs well
#no scent
Nel5950's avatar

Nel5950

3 months ago
Review

Works perfectly how its advertised, the changes it made to my redness and acne were done overnight. In addition to it combating irritated skin, it is hydrating as well. It’s not perfect since it hasn’t worked for my fungal acne and texture wise it is a little sticky but it absorbs into my skin very quickly. I find the shea butter can be an issue for me personally in skincare since it will also Show more

#great value
#hydrating
#broke me out
#sticky