The INKEY List Peptide Volumizing Hair Treatment Versus The INKEY List PCA Bond Repair Hair Treatment

The INKEY List Peptide Volumizing Hair Treatment Versus The INKEY List PCA Bond Repair Hair Treatment

What's inside

Key Ingredients

No key ingredients

Benefits

Concerns

Ingredients Side-by-side

Water

Pisum Sativum Peptide

Betaine

Glycerin

Panthenol

PEG-40 Hydrogenated Castor Oil

Phenoxyethanol

Polyquaternium-37

Citronellyl Methylcrotonate

Ethylhexylglycerin

Ceratonia Siliqua Seed Extract

Hydrolyzed Soy Protein

Zea Mays Starch

Leuconostoc/Radish Root Ferment Filtrate

Trisodium Ethylenediamine Disuccinate

Polyquaternium-16

Potassium Sorbate

Sodium Benzoate

Guar Hydroxypropyltrimonium Chloride

Polyquaternium-7

Water, Pisum Sativum Peptide, Betaine, Glycerin, Panthenol, PEG-40 Hydrogenated Castor Oil, Phenoxyethanol, Polyquaternium-37, Citronellyl Methylcrotonate, Ethylhexylglycerin, Ceratonia Siliqua Seed Extract, Hydrolyzed Soy Protein, Zea Mays Starch, Leuconostoc/Radish Root Ferment Filtrate, Trisodium Ethylenediamine Disuccinate, Polyquaternium-16, Potassium Sorbate, Sodium Benzoate, Guar Hydroxypropyltrimonium Chloride, Polyquaternium-7

Amodimethicone

Butylene Glycol

Bis-PCA Dimethicone

Sorbitan Laurate

Cetrimonium Chloride

Trideceth-12

Hydrolyzed Pea Protein Pg-Propyl Silanetriol

Aminomethyl Propanol

Aloe Barbadensis Leaf Juice Powder

Disodium PEG-12 Dimethicone Sulfosuccinate

Citric Acid

Polyglyceryl-4 Laurate

Alcohol

Helianthus Annuus Seed Extract

Dilauryl Citrate

Avena Strigosa Seed Extract

Lecithin

Water, Amodimethicone, Butylene Glycol, Betaine, Bis-PCA Dimethicone, Sorbitan Laurate, Cetrimonium Chloride, Panthenol, Trideceth-12, Glycerin, PEG-40 Hydrogenated Castor Oil, Sodium Benzoate, Hydrolyzed Pea Protein Pg-Propyl Silanetriol, Aminomethyl Propanol, Aloe Barbadensis Leaf Juice Powder, Disodium PEG-12 Dimethicone Sulfosuccinate, Potassium Sorbate, Citric Acid, Polyglyceryl-4 Laurate, Alcohol, Helianthus Annuus Seed Extract, Dilauryl Citrate, Phenoxyethanol, Avena Strigosa Seed Extract, Lecithin

Alternatives

Ingredients Explained

These ingredients are found in both products.

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

Betaine is a humectant. Like hyaluronic acid, it helps attract and retain moisture in the skin. It’s known for being gentle and for helping the skin maintain balanced hydration.

Betaine is mainly used to improve hydration and support calmer skin. It helps skin cells regulate water balance because it functions as an osmolyte.

Some studies suggest betaine may support making skin tone more even.

Fun fact: Betaine naturally exists in the skin and the body. In cosmetic products, it can be either plant-derived (most commonly from sugar beets) or synthetically produced for consistency and stability.

Betaine is also known as trimethylglycine.

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.

PEG-40 Hydrogenated Castor Oil is an emulsifier derived from castor oil.

As an emulsifying agent, it helps other ingredients like fragrances and fat-soluble vitamins dissolve cohesively.

Due to its large molecule size, it doesn't penetrate beyond the skin's surface.

This ingredient has a solid regulatory track record; the CIR Expert Panel first concluded it was safe for use in cosmetics at concentrations up to 100% in 1997. A 2012 reassessment reaffirmed that finding. Safety studies have also found no irritation or evidence of toxicity.

A 2019 study did find this ingredient to grow Malassezia, so this ingredient may not be fungal acne safe.

Phenoxyethanol is one of the most widely used preservatives in skincare (and for good reason!).

It has a large spectrum of antimicrobial activity and especially effective bacteria, yeast, and mold while only having a weak effect on your skin's natural microbiome.

On a cellular level, it disrupts the cell membranes of microbes by poking holes that make the cell leak. This shuts down the chemical reactions the microbe needs to make energy so it can no longer survive.

Another perk of this ingredient is that it stays functional across a wide pH range (3-10).

You'll often see it paired with boosters like Ethylhexylglycerin; one study showed that a 1:9 ratio of Ethylhexylglycerin to Phenoxyethanol damages bacterial membranes as effectively as doubling the Phenoxyethanol concentration on its own.

Typical use concentrations range from 0.3-1% depending on the formula, and this ingredient is capped at 1% int the EU.

Safety-wise, the fear mongering does not hold up to the evidence. The EU's Scientific Committee on Consumer Safety and FDA consider it safe as a preservative at up to 1%, including for children of all ages.

Adverse systemic effects only showed up in animal studies at exposures roughly 200x higher than what people get from cosmetics. And despite its very widespread use, this ingredient is a rare sensitizer and allergic reactions are uncommon.

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

This ingredient comes from potassium salt derived from sorbic acid. Sorbic acid is a natural antibiotic and effective against fungus.

Both potassium sorbate and sorbic acid can be found in baked goods, cheeses, dried meats, dried fruit, ice cream, pickles, wine, yogurt, and more.

You'll often find this ingredient used with other preservatives.

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.

It 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.

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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