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Kérastase Elixir Ultime Hydrating Hair Oil Serum Versus K18 Hair Leave-In Molecular Repair Hair Mask

Hair Serum
Hair Mask
French Brand France
American Brand United States

Overview

What they are

These products are both reef safe . They have a total of 4 ingredients in common

Cool Features

They both contain Vitamin E

Suited For

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

Free From

They both do not contain any parabens or sulfates

What's Inside

They both contain harsh alcohols, common allergens and 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

At a glance

Click on any of the items below to learn more

Notable Ingredients

Benefits

Concerns

Notable Ingredients

Benefits

Concerns

Ingredients Side-by-side

found in both products
Elixir Ultime Hydrating Hair Oil Serum
Cyclopentasiloxane Emollient, Skin Conditioning, Solvent
Silicon Icon
SiliconSilicon Icon

Cyclopentasiloxane is a silicone used to improve texture and trap moisture. An easier name for this is D5.

Disliked Full details ->
Dimethiconol Emollient, Moisturising

Dimethiconol is a silicone that resembles the popular dimethicone. Like other silicones, it is an emollient. Emollients create a thin film on skin to prevent moisture from escaping.

Disliked Full details ->
Zea Mays Germ Oil Emollient, Skin Conditioning
Oil IconNot safe for Fungal Acne Icon
OilOil Icon Not safe for Fungal AcneNot safe for Fungal Acne Icon

Zea Mays Germ Oil comes from corn.

Unknown Full details ->
Argania Spinosa Kernel Oil Emollient, Skin Conditioning
Oil IconHelps hydrate Dry Skin IconNot safe for Fungal Acne Icon
OilOil Icon Helps hydrate Dry SkinHelps hydrate Dry Skin Icon Not safe for Fungal AcneNot safe for Fungal Acne Icon

Argania Spinosa Kernel Oil is derived from the kernels of the argania spinosa tree. You may know it as argan oil.

Sclerocarya Birrea Seed Oil Humectant
Oil IconNot safe for Fungal Acne Icon
OilOil Icon Not safe for Fungal AcneNot safe for Fungal Acne Icon

Sclerocarya Birrea Seed Oil is the oil expressed from the seeds of the Marula plant. In South Africa, Marula is called "an elephant's favorite treat".

Camellia Oleifera Seed Oil Skin Conditioning
Oil IconNot safe for Fungal Acne Icon
OilOil Icon Not safe for Fungal AcneNot safe for Fungal Acne Icon

Camellia Oleifera Seed Oil comes from a green tea plant native to China. It is closely related to Camellia sinensis. Both plants have very similar properties. This plant also has similar properties to olive oil.

Pentaclethra Macroloba Seed Oil Emollient
Oil IconNot safe for Fungal Acne Icon
OilOil Icon Not safe for Fungal AcneNot safe for Fungal Acne Icon

Pentaclethra Macroloba Seed Oil is an oil and isn't fungal acne safe.

Unknown Full details ->
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.

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 ->
Alpha-Isomethyl Ionone Perfuming, Skin Conditioning
Fragrance IconEU Allergen Icon
FragranceFragrance Icon EU AllergenEU Allergen Icon

Alpha-Isomethyl Ionone is a fragrance. It can be synthetically created or naturally occurring.

Unknown 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 ->
Coumarin Perfuming
Fragrance IconEU Allergen Icon
FragranceFragrance Icon EU AllergenEU Allergen Icon

Coumarins are a group of substances found naturally in plants. There are over 1300 types of coumarins identified. It has a natural vanilla scent.

Very Disliked Full details ->
Benzyl Alcohol Perfuming, Preservative, Solvent
Alcohol IconFragrance IconPreservative IconCan worsen Dry Skin IconMay worsen Oily Skin IconMay cause irritation IconEU Allergen IconMay worsen Eczema IconMay worsen Rosacea Icon
AlcoholAlcohol Icon FragranceFragrance Icon PreservativePreservative Icon 6 Concerns

Benzyl Alcohol is most commonly used as a preservative. It also has a subtle, sweet smell. Small amounts of Benzyl Alcohol is not irritating and safe to use in skincare products. Most Benzyl Alcohol is derived from fruits such as apricots.

Very Disliked Full details ->
Phyllanthus Emblica Fruit Extract Humectant, Skin Conditioning

We don't have a description for Phyllanthus Emblica Fruit Extract.

Unknown 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.
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 ->
Leave-In Molecular Repair Hair Mask
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.

Alcohol Denat. Antimicrobial, Astringent, Masking
Alcohol IconCan worsen Dry Skin IconMay worsen Oily Skin IconMay cause irritation IconMay worsen Eczema IconMay worsen Rosacea Icon
AlcoholAlcohol Icon 5 Concerns

Alcohol Denat. is an alcohol with a denaturant property. It is created by mixing ethanol with other additives.

Very Disliked Full details ->
Propylene Glycol Humectant, Skin Conditioning, Solvent
0 / 0 May worsen Eczema Icon
May worsen EczemaMay worsen Eczema Icon

Propylene Glycol is an odorless, colorless liquid. As a humectant, it helps skin retain moisture. It also aids in delivering active ingredients.

0 Com. / 0 Irr.
Disliked Full details ->
Cetearyl Alcohol Emollient, Emulsifying, Emulsion Stabilising
2 / 1 Fatty Alcohol IconMay worsen Oily Skin IconBad for Acne Prone Skin IconNot safe for Fungal Acne Icon
Fatty AlcoholFatty Alcohol Icon 3 Concerns

Cetearyl alcohol is a mixture of two fatty alcohols: cetyl alcohol and stearyl alcohol. It is mainly used as an emulsifier. Emulsifiers help prevent the separation of oils and products. Due to its composition, it can also be used to thicken a product or help create foam.

2 Com. / 1 Irr.
Very Disliked Full details ->
Dicaprylyl Ether Emollient, Skin Conditioning, Solvent

Dicaprylyl Ether is created from caprylic acid. It is a texture-enhancer and emollient.

Cetyl Esters Emollient, Skin Conditioning
1 / 1 Not safe for Fungal Acne Icon
Not safe for Fungal AcneNot safe for Fungal Acne Icon

Cetyl Esters is a synthetic wax made up of mostly fatty acids and fatty alcohols. It is strcturally similar to wax taken from whales.

1 Com. / 1 Irr.
Very Disliked Full details ->
Behentrimonium Chloride Preservative
Preservative Icon
PreservativePreservative Icon

This ingredient is a preservative and often used for it's anti-static properties. You'll most likely see this ingredient in hair conditioners.

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 ->
Sh-Oligopeptide-78
Peptide Icon
PeptidePeptide Icon

Sh-Oligopeptide-78 is a peptide.

Unknown Full details ->
Hydrolyzed Wheat Protein Skin Conditioning

We don't have a description for Hydrolyzed Wheat Protein.

Disliked Full details ->
Hydrolyzed Wheat Starch Skin Conditioning

We don't have a description for Hydrolyzed Wheat Starch.

Unknown Full details ->
Isopropyl Alcohol Solvent
0 / 0 Alcohol IconCan worsen Dry Skin IconMay worsen Oily Skin IconMay cause irritation IconMay worsen Eczema IconMay worsen Rosacea Icon
AlcoholAlcohol Icon 5 Concerns

Isopropyl Alcohol is more commonly known as rubbing alcohol. It is most commonly used as a solvent, meaning it helps other ingredients dissolve.

0 Com. / 0 Irr.
Very 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.
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 ->
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 ->
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 ->
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 ->
Geraniol Perfuming, Tonic
Fragrance IconEU Allergen Icon
FragranceFragrance Icon EU AllergenEU Allergen Icon

Geraniol is used to add fragrance/parfum to a product. It is the main component of citronellol. It is a monoterpenoid and an alcohol.

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 ->
Hexyl Cinnamal Perfuming
Fragrance IconEU Allergen Icon
FragranceFragrance Icon EU AllergenEU Allergen Icon

Hexyl Cinnamal is a fragrance ingredient with a similar scent to jasmine. It can be naturally found in chamomile essential oil.

Very Disliked Full details ->
Benzyl Alcohol Perfuming, Preservative, Solvent
Alcohol IconFragrance IconPreservative IconCan worsen Dry Skin IconMay worsen Oily Skin IconMay cause irritation IconEU Allergen IconMay worsen Eczema IconMay worsen Rosacea Icon
AlcoholAlcohol Icon FragranceFragrance Icon PreservativePreservative Icon 6 Concerns

Benzyl Alcohol is most commonly used as a preservative. It also has a subtle, sweet smell. Small amounts of Benzyl Alcohol is not irritating and safe to use in skincare products. Most Benzyl Alcohol is derived from fruits such as apricots.

Very Disliked 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.

Perfuming
Very Disliked

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

Linalool has the same effect as Limonene when exposed to air. Oxidized linalool can cause allergies and skin sensitivity.

Linalool has a scent that is floral, spicy tropical, and citrus-like.

Learn more about Linalool
Perfuming, Preservative, Solvent
Very Disliked

Benzyl Alcohol is most commonly used as a preservative. It also has a subtle, sweet smell. Small amounts of Benzyl Alcohol is not irritating and safe to use in skincare products. Most Benzyl Alcohol is derived from fruits such as apricots.

Benzyl Alcohol has both antibacterial and antioxidant properties. These properties help lengthen the shelf life of products. Benzyl Alcohol is a solvent and helps dissolve other ingredients. It can also improve the texture and spreadability.

Alcohol comes in many different forms. Different types of alcohol will have different effects on skin. This ingredient is an astringent alcohol.

Using high concentrations of these alcohols are drying on the skin. They may strip away your skin's natural oils and even damage your skin barrier. Astringent alcohols may also irritate skin.

Other types of astringent alcohols include:

According to the National Rosacea Society based in the US, you should be mindful of products with these alcohols in the top half of ingredients.

Any type of sanitizing product will have high amounts of alcohol to help kill bacteria and viruses.

Learn more about Benzyl Alcohol
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
Masking, Perfuming
Very Disliked

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

Also called "fragrance", this ingredient can be a blend of hundreds of chemicals or plant oils. This means every product with "fragrance" or "parfum" in the ingredients list is a different mixture.

In the US, the alternative name for parfum is 'fragrance'.

The term 'fragrance' is not regulated in many countries. In many cases, it is up to the brand to define this term.

For instance, many brands choose to label themselves as "fragrance-free" because they are not using synthetic fragrances. However, their products may still contain ingredients such as essential oils that are considered a fragrance by INCI standards.

One example is Calendula flower extract. Calendula is an essential oil that still imparts a scent or 'fragrance'.

Depending on the blend, the ingredients in the mixture can cause allergies and sensitivities on the skin. Some ingredients that are known EU allergens include linalool and citronellol.

Parfum can also be used to mask or cover an unpleasant scent.

The bottom line is: not all fragrances/parfum/ingredients are created equally. If you are worried about fragrances, we recommend taking a closer look at an ingredient. And of course, we always recommend speaking with a professional.

Learn more about Parfum

Ingredient Ratings

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

Elixir Ultime Hydrating Hair Oil Serum
1
4
7
4
liked
mixed
disliked
not rated
Leave-In Molecular Repair Hair Mask
4
15
2
liked
mixed
disliked
not rated

When to use

14 Routines
57% use in am
43% use in pm
50% use every day
27 Routines
41% use in am
59% use in pm
63% use every day
When to use See routines that use it ->

Reviews

Here's what our community thinks

Kérastase Elixir Ultime Hydrating Hair Oil Serum 16 ingredients

5.0 /5
from 1 rating

K18 Hair Leave-In Molecular Repair Hair Mask 21 ingredients

4.5 /5
from 2 ratings
BrittanyBotkins_920's avatar

BrittanyBotkins_920

1 year ago · Combination Skin
Review

Repaired my extremely bleach damaged hair as well as both of their shampoos.