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Overview

What they are

These products are both vegan, cruelty-free, and reef safe . They have a total of 4 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 oils, 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.

K18 Hair Leave-In Molecular Repair Hair Mask
K18 Hair PEPTIDE PREP™ pH Maintenance Shampoo

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

Benefits

Concerns

Ingredients Side-by-side

found in both products
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 ->
PEPTIDE PREP™ pH Maintenance Shampoo
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.

Sodium C14-16 Olefin Sulfonate Cleansing, Foaming
May cause irritation Icon
May cause irritationMay cause irritation Icon

Sodium C14-16 Olefin Sulfonate is a cleansing agent made from a mixture of long chain sulfonate salts. It can also help produce foam.

Very Disliked Full details ->
Cocamidopropyl Betaine Cleansing
May worsen Eczema Icon
May worsen EczemaMay worsen Eczema Icon

Cocamidopropyl Betaine is a fatty acid created by mixing similar compounds in coconut oil and dimethylaminopropylamine. Dimethylaminopropylamine is a diamine, an amine with two amino groups.

Disliked Full details ->
Sodium Methyl 2-Sulfolaurate Cleansing, Foaming

We don't have a description for Sodium Methyl 2-Sulfolaurate.

Unknown Full details ->
Sodium Lauryl Sulfoacetate Cleansing, Foaming

Sodium Lauryl Sulfoacetate is an organic salt with a naturally sweet odor.

Very Disliked Full details ->
Sh-Oligopeptide-78
Peptide Icon
PeptidePeptide Icon

Sh-Oligopeptide-78 is a peptide.

Unknown Full details ->
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.
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.
Sodium Phytate

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

Guar Hydroxypropyltrimonium Chloride Skin Conditioning

This ingredient is derived from guar gum.

Disodium 2-Sulfolaurate Cleansing

We don't have a description for Disodium 2-Sulfolaurate.

Unknown Full details ->
Caprylyl Glycol Emollient, Humectant, Skin Conditioning

Caprylyl Glycol is a humectant and emollient, meaning it attracts and preserves moisture.

Caprylhydroxamic Acid

Caprylhydroxamic Acid is a chelating agent.

Benzoic Acid Masking, Preservative
Preservative IconMay worsen Eczema Icon
PreservativePreservative Icon May worsen EczemaMay worsen Eczema Icon

Benzoic Acid is used to preserve and adjust the pH 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 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.

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 ->
Limonene Perfuming, Solvent
Fragrance Icon
FragranceFragrance Icon

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

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.

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

Sh-Oligopeptide-78 is a peptide.

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
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 two products.

Leave-In Molecular Repair Hair Mask
4
15
2
liked
mixed
disliked
not rated
PEPTIDE PREP™ pH Maintenance Shampoo
7
1
7
3
liked
mixed
disliked
not rated

When to use

20 Routines
50% use in am
50% use in pm
70% use every day
3 Routines
33% use in am
67% use in pm
67% use every day

Reviews

Here's what our community thinks

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.

K18 Hair PEPTIDE PREP™ pH Maintenance Shampoo 18 ingredients

PEPTIDE PREP™ pH Maintenance Shampoo hasn't been rated yet.
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