K18 Hair PEPTIDE PREP™ pH Maintenance Shampoo Versus Ouai Fine Hair Shampoo

K18 Hair PEPTIDE PREP™ pH Maintenance Shampoo Versus Ouai Fine Hair Shampoo

What's inside

Key Ingredients

No key ingredients

Benefits

Concerns

Ingredients Side-by-side

Water

Sodium C14-16 Olefin Sulfonate

Cocamidopropyl Betaine

Sodium Methyl 2-Sulfolaurate

Sodium Lauryl Sulfoacetate

Sh-Oligopeptide-78

Panthenol

Glycerin

Sodium Phytate

Guar Hydroxypropyltrimonium Chloride

Disodium 2-Sulfolaurate

Caprylyl Glycol

Caprylhydroxamic Acid

Benzoic Acid

Citric Acid

Sodium Hydroxide

Parfum

Limonene

Water, Sodium C14-16 Olefin Sulfonate, Cocamidopropyl Betaine, Sodium Methyl 2-Sulfolaurate, Sodium Lauryl Sulfoacetate, Sh-Oligopeptide-78, Panthenol, Glycerin, Sodium Phytate, Guar Hydroxypropyltrimonium Chloride, Disodium 2-Sulfolaurate, Caprylyl Glycol, Caprylhydroxamic Acid, Benzoic Acid, Citric Acid, Sodium Hydroxide, Parfum, Limonene

Sodium Methyl Cocoyl Taurate

PEG-200 Hydrogenated Glyceryl Palmate

Cocamide Mipa

Cocoglucosides Hydroxypropyltrimonium Chloride

Hydrolyzed Keratin

Biotin

Salvia Hispanica Seed Oil

Cetrimonium Chloride

Hydroxypropyl Guar Hydroxypropyltrimonium Chloride

Sodium Lauroyl Glycinate

PEG-150 Distearate

Propoxytetramethyl Piperidinyl Dimethicone

Trideceth-6

C11-15 Pareth-7

PEG-7 Glyceryl Cocoate

Sodium Chloride

Polyquaternium-7

Disodium EDTA

Tetrasodium EDTA

Potassium Sorbate

Sodium Benzoate

Phenoxyethanol

Benzyl Alcohol

Acetic Acid

Sodium Acetate

Benzyl Salicylate

Hexyl Cinnamal

Water, Sodium C14-16 Olefin Sulfonate, Cocamidopropyl Betaine, Sodium Methyl Cocoyl Taurate, PEG-200 Hydrogenated Glyceryl Palmate, Cocamide Mipa, Parfum, Panthenol, Cocoglucosides Hydroxypropyltrimonium Chloride, Hydrolyzed Keratin, Biotin, Salvia Hispanica Seed Oil, Cetrimonium Chloride, Hydroxypropyl Guar Hydroxypropyltrimonium Chloride, Glycerin, Sodium Lauroyl Glycinate, PEG-150 Distearate, Propoxytetramethyl Piperidinyl Dimethicone, Trideceth-6, C11-15 Pareth-7, PEG-7 Glyceryl Cocoate, Sodium Chloride, Polyquaternium-7, Disodium EDTA, Citric Acid, Sodium Hydroxide, Tetrasodium EDTA, Potassium Sorbate, Sodium Benzoate, Phenoxyethanol, Benzyl Alcohol, Acetic Acid, Sodium Acetate, Benzyl Salicylate, Limonene, Hexyl Cinnamal

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Alternatives

Ingredients Explained

These ingredients are found in both products.

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

Citric Acid is an alpha hydroxy acid (AHA) naturally found in citrus fruits like oranges, lemons, and limes.

Like other AHAs, citric acid can exfoliate skin by breaking down the bonds that hold dead skin cells together. This helps reveal smoother and brighter skin underneath.

However, this exfoliating effect only happens at high concentrations (20%) which can be hard to find in cosmetic products.

Due to this, citric acid is usually included in small amounts as a pH adjuster. This helps keep products slightly more acidic and compatible with skin's natural pH.

In skincare formulas, citric acid can:

While it can provide some skin benefits, research shows lactic acid and glycolic acid are generally more effective and less irritating exfoliants.

Most citric acid used in skincare today is made by fermenting sugars (usually from molasses). This synthetic version is identical to the natural citrus form but easier to stabilize and use in formulations.

Rosacea skin has a lower threshold for acids generally, with 62.5% of rosacea subjects in one study reacting to lactic acid in a sting test. This is why we mark citric acid as a potential rosacea trigger.

However, this ingredient shows up as a pH adjuster or chelator at roughly 0.1-1% in many products. These low levels are unlikely to be an issue for rosacea skin and becomes a potential trigger at exfoliating concentrations (20%). Because everybody's skin is unique, we recommend a patch test if you are unsure.

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

This ingredient is a surfactant and cleanser. It helps gather the dirt, pollutants, and other impurities in your skin to be washed away. It also helps thicken a product and make the texture more creamy.

Being created from coconut oil means Cocamidopropyl Betaine is hydrating for the skin.

While Cocamidopropyl Betaine was believed to be an allergen, a study from 2012 disproved this. It found two compounds in unpure Cocamidopropyl Betaine to be the irritants: aminoamide and 3-dimethylaminopropylamine. High-grade and pure Cocamidopropyl Betaine did not induce allergic reactions during this study.

Glycerin (or glycerol) is a compound naturally found in your skin. It's a powerhouse humectant that pulls water into the stratum corneum.

Topically, glycerin does several things at once:

Your skin makes glycerin on its own (mostly from sebaceous oil breakdown) and shuttles it to your outermost layer of skin, or your epidermis, via aquaporin-3.

Aquaporin-3 is a transporter that is essential for normal skin hydration, elasticity, and repair. Interestingly, mice lacking in AQP3 have dry and less elastic skin that can be fully corrected with glycerin.

This ingredient is non-irritating, plays well with almost every ingredient, and works across all skin types. Typical use is anywhere between 3-10% but can go up to 79% in some leave-on products.

Just know very high concentrations (>40%) can feel tacky in low humidity.

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

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

It's found in the peel oil of citrus fruits and other plants such as lavender and eucalyptus. The scent of limonene is generally described as "sweet citrus".

Limonene acts as an antioxidant, meaning it helps neutralize free radicals.

When exposed to air, oxidized limonene may sensitize the skin. Because of this, limonene is often avoided by people with sensitive skin.

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.

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.

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.

For instance, Habanolide is a proprietary trade name for a specific aroma chemical. When used as a fragrance ingredient in cosmetics, most aroma chemicals fall under the broad labeling category of “FRAGRANCE” or “PARFUM” according to EU and US regulations.

The term 'parfum' or '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.

Sodium C14-16 Olefin Sulfonate is a surfactant that helps water and oil mix so that dirt, sweat, sebum, and sunscreen can rinse away easily. It's not technically a sulfate, but behaves similarly in formulas.

What it does:

Sodium C14-16 Olefin Sulfonate is a strong cleansing surfactant and is much stronger than many mild cleansers. Because it works deeply, it can disrupt the skin's barrier. This can lead to dryness or irritation for those with sensitive skin.

Compared to gentler surfactants, it's effective but more likely to dry or irritate if not balanced with soothing ingredients.

CIR considers sodium α-olefin sulfonates (including C14-16) to be safe for use in rinse-off products when properly formulated. It is poorly absorbed through normal skin but absorption increases if the skin barrier is already damaged.

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.

In small amounts, sodium hydroxide is considered safe to use. However, large amounts may cause chemical burns due to its high alkaline.

Your skin has a natural pH and acid mantle. This acid mantle helps prevent harmful bacteria from breaking through. The acid mantle also helps keep your skin hydrated.

"Alkaline" refers to a high pH level. A low pH level would be considered acidic.

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. Remember to stay hydrated!

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