Necessaire The Shampoo Versus K18 Hair PEPTIDE PREP™ pH Maintenance Shampoo

Necessaire The Shampoo Versus K18 Hair PEPTIDE PREP™ pH Maintenance Shampoo

What's inside

Key Ingredients

Benefits

Concerns

Ingredients Side-by-side

Water

Sodium Lauroyl Methyl Isethionate

Aloe Barbadensis Leaf Juice

Cocamidopropyl Betaine

Sodium Methyl Oleoyl Taurate

Sodium Cocoyl Isethionate

Propanediol

Niacinamide

Sodium Hyaluronate

Panthenol

Apium Graveolens Seed Extract

Persea Gratissima Oil

Glycerin

Disodium Cocoyl Glutamate

Caprylic/Capric Triglyceride

Citric Acid

Caprylhydroxamic Acid

Sodium Chloride

1,2-Hexanediol

Caprylyl Glycol

Sodium Benzoate

Water, Sodium Lauroyl Methyl Isethionate, Aloe Barbadensis Leaf Juice, Cocamidopropyl Betaine, Sodium Methyl Oleoyl Taurate, Sodium Cocoyl Isethionate, Propanediol, Niacinamide, Sodium Hyaluronate, Panthenol, Apium Graveolens Seed Extract, Persea Gratissima Oil, Glycerin, Disodium Cocoyl Glutamate, Caprylic/Capric Triglyceride, Citric Acid, Caprylhydroxamic Acid, Sodium Chloride, 1,2-Hexanediol, Caprylyl Glycol, Sodium Benzoate

Sodium C14-16 Olefin Sulfonate

Sodium Methyl 2-Sulfolaurate

Sodium Lauryl Sulfoacetate

Sh-Oligopeptide-78

Sodium Phytate

Guar Hydroxypropyltrimonium Chloride

Disodium 2-Sulfolaurate

Benzoic 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

Alternatives

Ingredients Explained

These ingredients are found in both products.

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

Caprylhydroxamic Acid is a chelating agent that helps cosmetics stay fresh, stable, and consistent over time.

Chelating agents help prevent metal ions from binding to other ingredients. This helps prevent unwanted reactions and effects from using the product. It also helps prevent the growth of unwanted microbes in products that contain water.

Caprylhydroxamic Acid is often used with natural antimicrobial products as an alternative to preservatives.

Caprylyl Glycol is a humectant, skin conditioner, emollient, and preservative booster derived from either caprylic acid or synthetically created.

Typical use levels vary from 0.3-1% as a preservative booster and go up to 2% to condition skin.

Because it is not a free-fatty acid, this ingredient is fungal acne safe (there's nothing for Malassezia to feed on).

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.

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.

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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