Peptide Skincare & BeautySkin science and ingredient guides

Skin science article

The INKEY List Caffeine Stimulating Scalp Treatment Versus The INKEY List Peptide Volumizing Hair Treatment

The INKEY List Caffeine Stimulating Scalp Treatment Versus The INKEY List Peptide Volumizing Hair Treatment What's inside Key Ingredients Benefits Concerns No concerns Ingredients Side-by-side Water Betaine Caffeine Panthenol Phenoxyethanol Glycerin Xanthan Gu

The INKEY List Caffeine Stimulating Scalp Treatment Versus The INKEY List Peptide Volumizing Hair Treatment

What's inside

Key Ingredients

Benefits

Concerns

No concerns

Ingredients Side-by-side

Water

Betaine

Caffeine

Panthenol

Phenoxyethanol

Glycerin

Xanthan Gum

Ethylhexylglycerin

Trisodium Ethylenediamine Disuccinate

Lactic Acid

Sodium Metabisulfite

Glycine

Larix Europaea Wood Extract

Camellia Sinensis Extract

Zinc Chloride

Water, Betaine, Caffeine, Panthenol, Phenoxyethanol, Glycerin, Xanthan Gum, Ethylhexylglycerin, Trisodium Ethylenediamine Disuccinate, Lactic Acid, Sodium Metabisulfite, Glycine, Larix Europaea Wood Extract, Camellia Sinensis Extract, Zinc Chloride

Pisum Sativum Peptide

PEG-40 Hydrogenated Castor Oil

Polyquaternium-37

Citronellyl Methylcrotonate

Ceratonia Siliqua Seed Extract

Hydrolyzed Soy Protein

Zea Mays Starch

Leuconostoc/Radish Root Ferment Filtrate

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

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.

Ethylhexylglycerin is created from glycerin. It is a multitasker ingredient that:

The CIR Expert Panel found minimal skin absorption or sensitization of any kind in a safety assessment. Though this ingredient is considered well-tolerated, a small number of cases of allergic dermatitis have been published since 2002. Just be sure to patch test if you are unsure.

Industry-reported use ranges from 8% in rinse-off products and 2% in leave-on formulations.

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.

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.

Trisodium Ethylenediamine Disuccinate is used to help stabilize a product.

It is a chelating agent, meaning it helps prevent metal ions from binding to other ingredients. This prevents unwanted reactions in products. Metal ions can come into a product via the water ingredient. They are found in trace amounts and are not known to be harmful.

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!

Similar Comparisons

The reference edit

Ingredients, questions
& further reading.

Connected source records selected through this article’s public topic index.

01

Formula cabinet

Ingredients & structured notes

02

Product index

Related product references

03

Comparison edit

Read side by side