Peptide Skincare & BeautySkin science and ingredient guides

Skin science article

The INKEY List Caffeine Eye Cream Versus AOA Skin Caffeine 10,000ppm Eye Cream

The INKEY List Caffeine Eye Cream Versus AOA Skin Caffeine 10,000ppm Eye Cream This anti-aging eye moisturizer is formulated around Caffeine and Palmitoyl Tetrapeptide-7 to soften the look of wrinkles. This anti-aging eye moisturizer is formulated around Caffe

The INKEY List Caffeine Eye Cream Versus AOA Skin Caffeine 10,000ppm Eye Cream

This anti-aging eye moisturizer is formulated around Caffeine and Palmitoyl Tetrapeptide-7 to soften the look of wrinkles.

This anti-aging eye moisturizer is formulated around Caffeine and Ceramide NP to soften the look of wrinkles and strengthen the skin barrier.

What's inside

Key Ingredients

Benefits

Concerns

Ingredients Side-by-side

Water

Glycerin

Dicaprylyl Carbonate

Propanediol

Polyglyceryl-6 Distearate

Cetyl Alcohol

Glyceryl Behenate

Phenoxyethanol

Hydroxyethyl Acrylate/Sodium Acryloyldimethyl Taurate Copolymer

Jojoba Esters

Albizia Julibrissin Bark Extract

Squalane

Caffeine

Polyglyceryl-3 Beeswax

Phospholipids

Ethylhexylglycerin

Xanthan Gum

Glycine Soja Oil

Polysorbate 60

Sodium Phytate

Glycolipids

Sorbitan Isostearate

Butylene Glycol

Citric Acid

Glycine Soja Sterols

Leuconostoc/Radish Root Ferment Filtrate

Hyaluronic Acid

Sodium Benzoate

Tocopherol

Carbomer

Darutoside

Sodium Lactate

Polysorbate 20

Palmitoyl Tetrapeptide-7

Palmitoyl Tripeptide-1

Water, Glycerin, Dicaprylyl Carbonate, Propanediol, Polyglyceryl-6 Distearate, Cetyl Alcohol, Glyceryl Behenate, Phenoxyethanol, Hydroxyethyl Acrylate/Sodium Acryloyldimethyl Taurate Copolymer, Jojoba Esters, Albizia Julibrissin Bark Extract, Squalane, Caffeine, Polyglyceryl-3 Beeswax, Phospholipids, Ethylhexylglycerin, Xanthan Gum, Glycine Soja Oil, Polysorbate 60, Sodium Phytate, Glycolipids, Sorbitan Isostearate, Butylene Glycol, Citric Acid, Glycine Soja Sterols, Leuconostoc/Radish Root Ferment Filtrate, Hyaluronic Acid, Sodium Benzoate, Tocopherol, Carbomer, Darutoside, Sodium Lactate, Polysorbate 20, Palmitoyl Tetrapeptide-7, Palmitoyl Tripeptide-1

Cetyl Ethylhexanoate

Polyglyceryl-3 Methylglucose Distearate

Trimethylpentanediol/Adipic Acid Copolymer

Caprylic/Capric Triglyceride

Cetearyl Alcohol

Glyceryl Stearate

Butyrospermum Parkii Butter

PEG-100 Stearate

Chlorphenesin

Triethanolamine

Cholesterol

Ceramide NP

Disodium EDTA

Water, Glycerin, Squalane, Cetyl Ethylhexanoate, Butylene Glycol, Polyglyceryl-3 Methylglucose Distearate, Trimethylpentanediol/Adipic Acid Copolymer, Caprylic/Capric Triglyceride, Cetearyl Alcohol, Glyceryl Stearate, Butyrospermum Parkii Butter, Caffeine, Phenoxyethanol, PEG-100 Stearate, Chlorphenesin, Carbomer, Triethanolamine, Cholesterol, Ethylhexylglycerin, Xanthan Gum, Ceramide NP, Disodium EDTA

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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.

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.

Caffeine is a naturally occurring plant compound found in coffee beans, tea leaves, cocoa pods, and guarana.

As an antioxidant, caffeine protects your skin from free radical damage caused by UV exposure and envionrmnetal stressors.

Early research also shows that caffeine can help calm redness, soothe irritated skin, and support hair growth by stimulating microcirculation in the scalp.

You might have seen eye creams marketing caffeine as a depuffing ingredient. This is because it is a vasoconstrictor meaning it can temporarily constrict blood vessels, though clinical evidence for this specific use is still limited.

Most skincare products contain this ingredient at concentrations between 1-6%. It is able to penetrate skin easily regardless of skin type or thickness.

Just so you know, a very small number of case reports describe caffeine-induced allergy. This ingredient is generally well-tolerated, non-irritating, and non-sensitizing for the majority of people.

Carbomer is a synthetic thickening and gelling agent. It's basically the ingredient that gives a lot of serums, gels, creams, and sunscreens their smooth, non-sticky texture.

Although legally permitted at very high levels, carbomers are normally used at concentrations below 1%.

It also needs to be neutralized to actually thicken, and because it is a large molecule, it doesn't really penetrate the skin barrier.

Allergy-wise, the risk is very low. Clinical studies show carbomers have low potential for skin irritation/sensitization even at concentrations up to 100%.

A 2024 UK study patch-tested 1,302 patients and found true allergy to the parent group of carbomer to be rare with no confirmed relevant reactions.

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.

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.

Squalane is the hydrogenated and shelf-stable form of squalene (a lipid that naturally occurs in human sebum).

It is an emollient and skin conditioning agent that is able to integrate seamlessly into the skin's lipid barrier without clogging pores.

This is due to how structurally similar it is to what your skin already produces.

Though it is mostly an emollient that helps soften and hydrate skin, it also has some humectant and occlusive action. Humectants help the skin retain moisture while occlusives seal it in, making squalane a triple-threat moisturizer.

Research shows it has antioxidant capabilities that help protect against stressors like UV exposure, specifically UVA induced oxidative stress. This study also found that it supports collagen biosynthesis in human dermal fibroblasts.

No clinical study has reported significant adverse effects and irritation reactions are very rare from this ingredient (even at 100% concentration).

Overall, it's a fantastic ingredient for hydration and is suitable for all skin types.

This depends on the source. Squalane can be derived from both plants and animals. Most squalane used in skincare comes from plants.

Please note: the source of squalane is only known if disclosed by the brand. We recommend reaching out to the brand if you have any questions about their squalane.

Read more about squalene with an "e".

Though squalane is often called an oil, it’s technically not one. It is a hydrocarbon, meaning it is only made of carbon and hydrogen. True oils are triglycerides and made of fatty acids and glycerol.

The term “oil-free” isn’t regulated so companies can define it however they want. Some exclude all oils, while others just avoid mineral oil or comedogenic oils.

Squalane has a comedogenic rating of 1 from the original 1972 study that tested raw ingredients under occlusion on rabbit ears. This system is not standardized or peer-reviewed, and using the raw ingredients is very different from how diluted cosmetic formulations are used on human skin.

A comedogenic rating of 1 means it is "unlikely to clog pores" according to the original rating system.

The overall formula of a product matters more than the individual ingredients on whether or not it will cause clogged pores.

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!

Xanthan gum is used as a stabilizer and thickener within cosmetic products. It helps give products a sticky, thick feeling - preventing them from being too runny.

On the technical side of things, xanthan gum is a polysaccharide - a combination consisting of multiple sugar molecules bonded together.

Xanthan gum is a pretty common and great ingredient. It is a natural, non-toxic, non-irritating ingredient that is also commonly used in food products.

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

Ingredient index

Ingredients Explained

  1. 01These ingredients are found in both products.
  2. 02Ingredients higher up in an ingredient list are typically present in a larger amount.
  3. 03Butylene Glycol (or BG) is used within cosmetic products for a few different reasons:
  4. 04Overall, Butylene Glycol is a safe and well-rounded ingredient that works well with other ingredients.
  5. 05Though 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.
  6. 06Caprylyl Glycol is a humectant, skin conditioner, emollient, and preservative booster derived from either caprylic acid or synthetically created.
  7. 07Typical use levels vary from 0.3-1% as a preservative booster and go up to 2% to condition skin.
  8. 08Because it is not a free-fatty acid, this ingredient is fungal acne safe (there's nothing for Malassezia to feed on).
  9. 09Carbomer is a synthetic thickening and gelling agent. It's basically the ingredient that gives a lot of serums, gels, creams, and sunscreens their smooth, non-sticky texture.
  10. 10Although legally permitted at very high levels, carbomers are normally used at concentrations below 1%.
  11. 11It also needs to be neutralized to actually thicken, and because it is a large molecule, it doesn't really penetrate the skin barrier.
  12. 12Allergy-wise, the risk is very low. Clinical studies show carbomers have low potential for skin irritation/sensitization even at concentrations up to 100%.
  13. 13A 2024 UK study patch-tested 1,302 patients and found true allergy to the parent group of carbomer to be rare with no confirmed relevant reactions.
  14. 14Glycerin (or glycerol) is a compound naturally found in your skin. It's a powerhouse humectant that pulls water into the stratum corneum.
  15. 15Topically, glycerin does several things at once:
  16. 16Your 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.
  17. 17Aquaporin-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.
  18. 18This 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.
  19. 19Just know very high concentrations (>40%) can feel tacky in low humidity.
  20. 20Glycerin is the name for this ingredient in American English. British English uses Glycerol/Glycerine.
Source · skinsort.com
02

Product index

Related product references

Product

The Inkey List Retinol Eye Cream

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Source: incidecoder.comView reference →

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The Inkey List Polyglutamic Acid

The Inkey List Polyglutamic Acid The Inkey List Polyglutamic Acid ingredients explained: Aqua (Water), Dimethicone, Butylene Glycol, Bis-PEG-12 Dimethicone, Glycerin, Polymethylsilsesquioxa…

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03

Comparison edit

Read side by side