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Ouai Hydrating Scalp Serum for Healthy, Fuller Looking Hair Versus The INKEY List Peptide Volumizing Hair Treatment - EU

Hair Serum
Hair Serum
American Brand United States
British Brand United Kingdom

Updated on June 18, 2024

Overview

What they are

These products are both vegan, cruelty-free, and reef safe hair serums. They have a total of 6 ingredients in common

Cool Features

They both contain peptides

Suited For

They're both likely to be good for dry skin and brightening skin

Free From

They both do not contain any harsh alcohols, parabens, silicones or sulfates

What's Inside

They both contain fragrances

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
ph level
4.1

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
Hydrating Scalp Serum for Healthy, Fuller Looking Hair
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.

Polysorbate 20 Emulsifying
0 / 0 Not safe for Fungal Acne Icon
Not safe for Fungal AcneNot safe for Fungal Acne Icon

Polysorbate 20 is made by combining ethoxylation of sorbitan, ethylene oxide, and lauric acid. It is a mild cleansing agent, surfactant, and emulsifier.

0 Com. / 0 Irr.
Very Disliked Full details ->
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.
Glycerin Humectant, Skin Conditioning, Skin Protecting
0 / 0 Helps hydrate Dry Skin IconHelps brighten skin Icon
2 Benefits

Glycerin is already naturally found in your skin. It helps moisturize and protect your skin.

0 Com. / 0 Irr.
Polyquaternium-7

Polyquaternium-7 is a light to clear colored liquid. It is commonly found in haircare products for its film-forming and anti-static properties.

Unknown Full details ->
Rhodiola Rosea Extract Emollient

We don't have a description for Rhodiola Rosea Extract.

Unknown Full details ->
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.
Tocopheryl Acetate Antioxidant, Skin Conditioning
0 / 0 Vitamin E IconAntioxidant IconHelps brighten skin Icon
Vitamin EVitamin E Icon AntioxidantAntioxidant Icon Helps brighten skinHelps brighten skin Icon

Tocopheryl Acetate is AKA Vitamin E. It is an antioxidant and protects your skin from free radicals. Free radicals damage the skin by breaking down collagen.

0 Com. / 0 Irr.
Acetyl Tetrapeptide-3 Skin Protecting
Peptide Icon
PeptidePeptide Icon

Acetyl Tetrapeptide-3 is a peptide.

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.
Rosa Centifolia Flower Extract Astringent, Masking, Skin Conditioning

We don't have a description for Rosa Centifolia Flower Extract.

Unknown Full details ->
Dextran

We don't have a description for Dextran.

Unknown Full details ->
Trifolium Pratense Flower Extract Astringent, Masking
Good for Minimizing Pores Icon
Good for Minimizing PoresGood for Minimizing Pores Icon

Trifolium Pratense Flower Extract can help to reduce large pores.

Unknown Full details ->
Acanthopanax Senticosus Root Extract Skin Conditioning, Soothing

We don't have a description for Acanthopanax Senticosus Root Extract.

Unknown Full details ->
Rhaponticum Carthamoides Root Extract Skin Conditioning

We don't have a description for Rhaponticum Carthamoides Root Extract.

Unknown Full details ->
Inonotus Obliquus Extract Skin Conditioning

We don't have a description for Inonotus Obliquus Extract.

Selaginella Lepidophylla Extract Emollient

We don't have a description for Selaginella Lepidophylla Extract.

Unknown Full details ->
Ethylhexylglycerin Skin Conditioning

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

Disodium EDTA

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

Disliked Full details ->
Sodium Hydroxide Buffering

Sodium Hydroxide is also known as lye or caustic soda. It is used to adjust the pH of products; many ingredients require a specific pH to be effective.

Acrylates/C10-30 Alkyl Acrylate Crosspolymer Emulsion Stabilising

Acrylates/C10-30 Alkyl Acrylate Crosspolymer is a synthetic polymer. It is used to thicken and improve the texture of products.

Disliked Full details ->
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 Benzoate Masking, Preservative
Preservative Icon
PreservativePreservative Icon

Sodium Benzoate is a preservative. It's used in both cosmetic and food products to inhibit the growth of mold and bacteria. It is typically produced synthetically.

Disliked Full details ->
Phenoxyethanol Preservative
Preservative Icon
PreservativePreservative Icon

Phenoxyethanol is a preservative that has germicide, antimicrobial, and aromatic properties. Studies show that phenoxyethanol can prevent microbial growth. By itself, it has a scent that is similar to that of a rose.

Very Disliked Full details ->
Parfum Masking, Perfuming
Fragrance IconMay worsen Eczema IconMay worsen Rosacea Icon
FragranceFragrance Icon 2 Concerns

Parfum is a catch-all term for an ingredient or more that is used to give a scent to products.

Very Disliked Full details ->
Eugenol Perfuming, Tonic
Fragrance IconMay cause irritation IconEU Allergen Icon
FragranceFragrance Icon 2 Concerns

Eugenol is naturally found in cloves, basil, and bay leaves. It is an aromatic oil used to add fragrance to a product. The scent of eugenol is described as "clove-like". Eugenol is a known EU allergen, meaning it causes contact allergies.

Very Disliked Full details ->
Limonene Perfuming, Solvent
Fragrance Icon
FragranceFragrance Icon

Limonene is a fragrance that adds scent and taste to a formulation.

Very Disliked Full details ->
Linalool Perfuming
Fragrance IconMay cause irritation IconEU Allergen Icon
FragranceFragrance Icon 2 Concerns

Linalool is a fragrance and helps add scent to products. It's derived from common plants such as cinnamon, mint, citrus, and lavender.

Very Disliked Full details ->
Peptide Volumizing Hair Treatment
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.

Pisum Sativum Peptide Skin Conditioning
Peptide Icon
PeptidePeptide Icon

Pisum Sativum Peptide is a peptide.

Unknown Full details ->
Betaine Humectant, Skin Conditioning
Helps hydrate Dry Skin IconHelps reduce Skin Redness IconHelps reduce irritation Icon
3 Benefits

Betaine is a common humectant (a substance that promotes retention of moisture). It's known to be gentle on the skin and can help balance hydration.

Glycerin Humectant, Skin Conditioning, Skin Protecting
0 / 0 Helps hydrate Dry Skin IconHelps brighten skin Icon
2 Benefits

Glycerin is already naturally found in your skin. It helps moisturize and protect your skin.

0 Com. / 0 Irr.
Panthenol Skin Conditioning
0 / 0 Helps reduce irritation Icon
Helps reduce irritationHelps reduce irritation Icon

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

0 Com. / 0 Irr.
Peg-40 Hydrogenated Castor Oil Emulsifying
Oil IconNot safe for Fungal Acne Icon
OilOil Icon Not safe for Fungal AcneNot safe for Fungal Acne Icon

Peg-40 Hydrogenated Castor Oil is derived from castor oil and polyethylene glycol (PEG). It is used as a emollient and emulsifier.

Very Disliked Full details ->
Phenoxyethanol Preservative
Preservative Icon
PreservativePreservative Icon

Phenoxyethanol is a preservative that has germicide, antimicrobial, and aromatic properties. Studies show that phenoxyethanol can prevent microbial growth. By itself, it has a scent that is similar to that of a rose.

Very Disliked Full details ->
Polyquaternium-37

We don't have a description for Polyquaternium-37.

Citronellyl Methylcrotonate Masking, Perfuming
Fragrance Icon
FragranceFragrance Icon

Citronellyl Methylcrotonate is a fragrance.

Unknown Full details ->
Ethylhexylglycerin Skin Conditioning

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

Ceratonia Siliqua Seed Extract Skin Conditioning

We don't have a description for Ceratonia Siliqua Seed Extract.

Unknown Full details ->
Hydrolyzed Soy Protein Humectant, Skin Conditioning

This ingredient is a vegetable-derived protein made to mimic hydrolyzed collagen. It is created from soy, or glycine soja.

Disliked Full details ->
Zea Mays Starch Abrasive, Absorbent, Skin Protecting
Exfoliant Icon
ExfoliantExfoliant Icon

Zea Mays Starch is starch made from corn. You might know this as cornstarch . It is used to thicken a product. It can replace talc as an absorbent.

Disliked Full details ->
Leuconostoc/Radish Root Ferment Filtrate Antimicrobial

Leuconostoc/Radish Root Ferment Filtrate is a natural preservative. It comes from fermenting radish roots with a bacteria called leuconostoc. Leuconostoc comes from lactic acid. This bacteria is used to make the traditional Korean side-dish, kimchi. It is also used to make sourdough bread (both incredibly yummy foods).

Trisodium Ethylenediamine Disuccinate

Trisodium Ethylenediamine Disuccinate is used to help stabilize a product.

Polyquaternium-16

We don't have a description for Polyquaternium-16.

Unknown Full details ->
Potassium Sorbate Preservative
Preservative Icon
PreservativePreservative Icon

Potassium Sorbate is a preservative used to prevent yeast and mold in products. It is commonly found in both cosmetic and food products.

Disliked Full details ->
Sodium Benzoate Masking, Preservative
Preservative Icon
PreservativePreservative Icon

Sodium Benzoate is a preservative. It's used in both cosmetic and food products to inhibit the growth of mold and bacteria. It is typically produced synthetically.

Disliked Full details ->
Guar Hydroxypropyltrimonium Chloride Skin Conditioning

This ingredient is derived from guar gum.

Polyquaternium-7

Polyquaternium-7 is a light to clear colored liquid. It is commonly found in haircare products for its film-forming and anti-static properties.

Unknown Full details ->

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
Humectant, Skin Conditioning, Skin Protecting
Loved

Glycerin is already naturally found in your skin. It helps moisturize and protect your skin.

A study from 2016 found glycerin to be more effective as a humectant than AHAs and hyaluronic acid.

As a humectant, it helps the skin stay hydrated by pulling moisture to your skin. The low molecular weight of glycerin allows it to pull moisture into the deeper layers of your skin.

Hydrated skin improves your skin barrier; Your skin barrier helps protect against irritants and bacteria.

Glycerin has also been found to have antimicrobial and antiviral properties. Due to these properties, glycerin is often used in wound and burn treatments.

In cosmetics, glycerin is usually derived from plants such as soybean or palm. However, it can also be sourced from animals, such as tallow or animal fat.

This ingredient is organic, colorless, odorless, and non-toxic.

Glycerin is the name for this ingredient in American English. British English uses Glycerol/Glycerine.

Learn more about Glycerin

Polyquaternium-7 is a light to clear colored liquid. It is commonly found in haircare products for its film-forming and anti-static properties.

According to a manufacturer, it is a non-paraben and specially developed for negatively charged surfactant systems. This makes it a great hairstyle holder and helps to improve wet hair detangling without adding buildup.

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.

Masking, Preservative
Disliked

Sodium Benzoate is a preservative. It's used in both cosmetic and food products to inhibit the growth of mold and bacteria. It is typically produced synthetically.

Both the US FDA and EU Health Committee have approved the use of sodium benzoate. In the US, levels of 0.1% (of the total product) are allowed.

Sodium benzoate works as a preservative by inhibiting the growth of bacteria inside of cells. It prevents the cell from fermenting a type of sugar using an enzyme called phosphofructokinase.

Sodium Benzoate is the salt of benzoic acid. Foods containing sodium benzoate include soda, salad dressings, condiments, fruit juices, wines, and snack foods.

Studies for using ascorbic acid and sodium benzoate in cosmetics are lacking, especially in skincare routines with multiple steps.

We always recommend speaking with a professional, such as a dermatologist, if you have any concerns.

Learn more about Sodium Benzoate
Preservative
Very Disliked

Phenoxyethanol is a preservative that has germicide, antimicrobial, and aromatic properties. Studies show that phenoxyethanol can prevent microbial growth. By itself, it has a scent that is similar to that of a rose.

It's often used in formulations along with Caprylyl Glycol to preserve the shelf life of products.

Ingredient Ratings

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

Hydrating Scalp Serum for Healthy, Fuller Looking Hair
7
3
10
8
liked
mixed
disliked
not rated
Peptide Volumizing Hair Treatment
8
1
6
5
liked
mixed
disliked
not rated

When to use

5 Routines
20% use in am
80% use in pm
80% use every day
6 Routines
33% use in am
67% use in pm
50% use every day