The INKEY List Polyglutamic Acid Hydrating Serum

The INKEY List Polyglutamic Acid Hydrating Serum

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Overview

What it is

Serum with 25 ingredients

Cool Features

It is vegan, cruelty-free, and reef safe

Suited For

It has ingredients that are good for dry skin, oily skin and scar healing

Free From

It doesn't contain any harsh alcohols, common allergens, fragrances, oils, parabens or sulfates

Fun facts

The INKEY List is from United Kingdom. This product is used in 306 routines created by our community.

We independently verify ingredients and our claims are backed by peer-reviewed research. Does this product need an update? Let us know.

What's inside

Benefits

Concerns

Ingredients Explained

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.

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!

Learn more about Water
Emollient, Skin Conditioning, Skin Protecting

Dimethicone is a type of synthetic silicone created from natural materials such as quartz. It is also known as polydimethylsiloxane.

What it does:

Dimethicone comes in different viscosities:

Depending on the viscosity, dimethicone has different properties.

Ingredients lists don't always show which type is used, so we recommend reaching out to the brand if you have questions about the viscosity.

This ingredient is unlikely to cause irritation because it does not get absorbed into skin. However, people with silicone allergies should be careful about using this ingredient.

Note: Dimethicone may contribute to pilling. This is because it is not oil or water soluble, so pilling may occur when layered with products. When mixed with heavy oils in a formula, the outcome is also quite greasy.

Learn more about Dimethicone
Humectant, Masking, Skin Conditioning

Butylene Glycol (or BG) is used within cosmetic products for a few different reasons:

Overall, Butylene Glycol is a safe and well-rounded ingredient that works well with other ingredients.

Though this ingredient works well with most skin types, some people with sensitive skin may experience a reaction such as allergic rashes, closed comedones, or itchiness.

Learn more about Butylene Glycol
Emollient, Skin Conditioning

Bis-PEG-12 Dimethicone is a type of silicone.

Humectant, Skin Conditioning, Skin Protecting

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.

Learn more about Glycerin

Polymethylsilsesquioxane is a silicone used as a film forming agent.

When applied to the skin, this ingredient creates an invisible film on the surface. This film still allows oxygen to pass through, but prevents moisture from escaping. This can help condition and hydrate the skin. It also leaves a silky feel when applied.

Polymethylsilsesquioxane has not been shown to clog pores. It has been deemed safe to use up to 55%, but most cosmetics use much less.

If you have concerns about using this ingredient, we recommend speaking with a professional.

Learn more about Polymethylsilsesquioxane

Polysilicone-11 is a film-forming silicone that creates a non-tacky and matte finish on the skin. It's commonly used to improve texture, absorb excess oil, and help active ingredients spread evenly.

Due to its "rubber-like" structure, it stays on the skin's surface instead of being absorbed. On the skin, it creates a flexible layer that enhances wearability and stability.

Preservative

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.

It's often used in formulations along with Caprylyl Glycol to preserve the shelf life of products.

Skin Conditioning

Polyglutamic Acid is made up many glutamic acids chained together. It is created from bacterial fermentation.

This ingredient is an effective skin hydrator and may help speed up wound healing. As a humectant, it draws and holds water to the skin. This ingredient is often compared to hyaluronic acid or glycerin. Similarly to hyaluronic acid, it can vary in molecular weights. This means polyglutamic acid is capable of bringing hydration to lower levels of the skin.

Fun fact: Polyglutamic Acid is found in the Japanese food, natto. It is also being used in cancer treatment studies.

Learn more about Polyglutamic Acid

This long ingredient is a copolymer of sodium acrylate and sodium acryloyldimethyl taurate monomers.

It is used to help stabilize other ingredients and create a thicker gel-like texture.

Emulsifiers prevent oils and waters from separating.

Learn more about Sodium Acrylate/Sodium Acryloyldimethyl Taurate Copolymer
Emollient, Skin Conditioning, Solvent

Isohexadecane is added to enhance texture, emulsify, and to help cleanse. It is an isoparrafin. It is a component of petrolatum.

Due to its large size, Isohexadecane is not absorbed by the skin. Instead, it sits on top and acts as an emollient. Emollients help keep your skin soft and smooth by trapping moisture within.

Isohexadecane is often used in products designed to help oily skin. It is lightweight and non-greasy while helping to moisturize. When mixed with silicones, it gives a product a silky feel.

Learn more about Isohexadecane
Solvent

Propanediol is an all-star ingredient. It softens, hydrates, and smooths the skin.ย 

Itโ€™s often used to:

Propanediol is not likely to cause sensitivity and considered safe to use. It is derived from corn or petroleum with a clear color and no scent.

Learn more about Propanediol
Cleansing, Foaming, Surfactant

Coco-Glucoside is a surfactant, or a cleansing ingredient. It is made from glucose and coconut oil.

Surfactants help gather dirt, oil, and other pollutants from your skin to be rinsed away.

This ingredient is considered gentle and non-comedogenic. However, it may still be irritating for some.

Learn more about Coco-Glucoside
Masking, Preservative

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.

Learn more about Sodium Benzoate
Emulsion Stabilising, Stabilising

Hydroxyethylcellulose is used to improve the texture of products. It is created from a chemical reaction involving ethylene oxide and alkali-cellulose. Cellulose is a sugar found in plant cell walls and help give plants structure.

This ingredient helps stabilize products by preventing ingredients from separating. It can also help thicken the texture of a product.

This ingredient can also be found in pill medicines to help our bodies digest other ingredients.

Learn more about Hydroxyethylcellulose
Emulsifying, Surfactant

Polysorbate 80 is a synthetic surfactant and emulsifier derived from sorbitol and oleic acid.

It reduces the surface tension between oil and water phases to help them stay mixed and stable in a formulation. In other words, it prevents your formulas from separating into an oily mess.

The CIR Expert Panel has evaluated the scientific data and found this ingredient to be safe, non-irritating, and non-sensitizing at concentrations up to 5% (it's even approved by the FDA as an OTC eye drop ingredient).

Learn more about Polysorbate 80
Skin Conditioning

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.

Learn more about Ethylhexylglycerin
Preservative

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.

Learn more about Potassium Sorbate
Cleansing, Emulsion Stabilising, Surfactant

Decyl Glucoside is a plant-derived surfactant and emulsion stabilizer. It is created by reacting glucose with the fatty acids from plants.

Like all surfactants, it works by lowering the surface tension between water and oil. This makes it so that dirt, sebum, and makeup can be lifted off your skin and rinsed away. It also produces a dense and creamy foam.

Because it has a neutral charge, it is compatible with a wide range of ingredients and stays stable across a broad pH range/water hardiness conditions.

Patch testing has shown it to have the lowest irritation potential among common cleansing surfactants (like SLS).

Typical use levels range from 5-20% in rinse-off cleansers.

One thing worth knowing: The American Contact Dermatitis Society named the parent family, alkyl glucosides, "Allergen of the Year" in 2017. The prevalence of allergy is pretty low but be sure to patch test if you've reacted to "gentle" or sulfate-free cleansers before.

This ingredient is fungal acne safe because the fatty alcohol portion of this ingredient is not within the C11-24 chain length that Malassezia can metabolize.

Learn more about Decyl Glucoside

We don't have a description for Dimethylacrylamide/Acrylic Acid/Polystyrene Ethyl Methacrylate Copolymer yet.

Emulsifying

Sorbitan Oleate is a PEG-free emulsifier made by esterifying sorbitol with oleic acid.

You'll likely see it paired with Polysorbate 80 to create the right emulsification balance.

Typical use levels in formulas range from 2-10%.

The CIR Expert Panel has concluded this ingredient to be safe as a cosmetic ingredient.

Since this ingredient is an ester of oleic acid, it may not be fungal acne safe. Oleic acid is a fatty acid that falls into the C11-24 range that Malassezia can metabolize.

Learn more about Sorbitan Oleate

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.

Emollient, Humectant, Skin Conditioning

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).

Learn more about Caprylyl Glycol
Emulsifying, Skin Conditioning, Solvent

Hexylene Glycol is a multitasker ingredient that works as a solvent, humectant, emulsifier, viscosity reducer, and preservative booster.

It is able to dissolve both water and oil-soluble ingredients to stabilize tricky actives and make products spread more easily.

As a humectant, it pulls water into the skin. But it's a pretty minor moisturizing ingredient compared to other humectants, like glycerin.

Interestingly, it can act as a mild penetration enhancer. One in vitro study on human skin found a 12% concentration upped the absorption of mometasone furoate (a medicinal ingredient used to treat inflammatory skin conditions) up to 7%.

This ingredient is typically used at levels of 0.1-10% depending on the role it's playing.

A patch test study on eczema patients didn't find a significant increase in irritation versus the control group, but the potential for irritation rises at higher concentrations.

Learn more about Hexylene Glycol
Skin Conditioning, Skin Protecting

Oryza Sativa Bran Extract comes from the outer layer of a rice kernel. It is a byproduct of milling rice, or the operation to produce a whole grain rice product.

This ingredient has moisturizing properties due to its components of polysaccharides and omega-3 fatty acids. It also contains calcium, selenium, phosphorus, iron, and zinc.

Oryza Sativa Bran Extract contains numerous antioxidants such as ferulic acid. Antioxidants help fight free-radical molecules. Free-radical molecules are capable of damaging our cells and other genetic material.

Learn more about Oryza Sativa Bran Extract

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Hydrating 60% Works Well 60% Absorbs Well 40%
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The INKEY List is a British brand

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ยท Updated July 10, 2025 Added by Klyn