The INKEY List 1% Retinol Serum Versus Peter Thomas Roth Peptide 21 Wrinkle Resist Serum

The INKEY List 1% Retinol Serum Versus Peter Thomas Roth Peptide 21 Wrinkle Resist Serum

This anti-aging serum is formulated around Retinol to soften the look of wrinkles and refine skin texture.

This anti-aging serum is formulated around Tripeptide-10 Citrulline and Acetyl Octapeptide-3 to soften the look of wrinkles.

What's inside

Key Ingredients

Benefits

Concerns

Ingredients Side-by-side

Water

Glycerin

Prunus Armeniaca Kernel Oil

Persea Gratissima Oil

Caprylic/Capric Triglyceride

Squalane

Cetearyl Alcohol

Glyceryl Stearate Se

Retinol

Phenoxyethanol

Hydroxyethyl Acrylate/Sodium Acryloyldimethyl Taurate Copolymer

Benzyl Alcohol

Phospholipids

Tocopherol

Polyacrylate Crosspolymer-6

Glycine Soja Oil

Ethylhexylglycerin

Glycolipids

Dehydroacetic Acid

Polysorbate 60

Sorbitan Isostearate

Trisodium Ethylenediamine Disuccinate

Glycine Soja Sterols

T-Butyl Alcohol

Water, Glycerin, Prunus Armeniaca Kernel Oil, Persea Gratissima Oil, Caprylic/Capric Triglyceride, Squalane, Cetearyl Alcohol, Glyceryl Stearate Se, Retinol, Phenoxyethanol, Hydroxyethyl Acrylate/Sodium Acryloyldimethyl Taurate Copolymer, Benzyl Alcohol, Phospholipids, Tocopherol, Polyacrylate Crosspolymer-6, Glycine Soja Oil, Ethylhexylglycerin, Glycolipids, Dehydroacetic Acid, Polysorbate 60, Sorbitan Isostearate, Trisodium Ethylenediamine Disuccinate, Glycine Soja Sterols, T-Butyl Alcohol

Rosa Centifolia Flower Water

Isopropyl Myristate

Mannitol

Butylene Glycol

Natto Gum

Tripeptide-10 Citrulline

Acetyl Octapeptide-3

Palmitoyl Hexapeptide-12

Acetyl Tetrapeptide-11

Acetyl Hexapeptide-8

Acetyl Hexapeptide-1

Palmitoyl Oligopeptide

Acetyl Tetrapeptide-9

Acetyl Tetrapeptide-2

Tripeptide-1

Palmitoyl Tetrapeptide-7

Hexapeptide-11

Dipeptide Diaminobutyroyl Benzylamide Diacetate

Palmitoyl Tripeptide-5

Trifluoroacetyl Tripeptide-2

Palmitoyl Tripeptide-1

Sodium Polyglutamate

Sodium Hyaluronate

Tocopheryl Acetate

Retinyl Palmitate

Ascorbic Acid

Hydrolyzed Soy Protein

Hydrolyzed Wheat Protein

Lecithin

Pseudoalteromonas Ferment Extract

Acrylates Copolymer

Magnesium Chloride

Polysorbate 20

Dimethyl Isosorbide

Acrylates/C10-30 Alkyl Acrylate Crosspolymer

Leuconostoc/Radish Root Ferment Filtrate

PEG-8 Dimethicone

Disodium Phosphate

Carbomer

Dextran

Sodium Lactate

Tetradecyl Aminobutyroylvalylaminobutyric Urea Trifluoroacetate

Xanthan Gum

Triethanolamine

Sodium Phosphate

Octyldodecanol

Silica

Sodium Propoxyhydroxypropyl Thiosulfate Silica

Sodium Hydroxide

Caprylyl Glycol

Potassium Sorbate

Sodium Benzoate

Water, Glycerin, Rosa Centifolia Flower Water, Isopropyl Myristate, Squalane, Mannitol, Butylene Glycol, Natto Gum, Tripeptide-10 Citrulline, Acetyl Octapeptide-3, Palmitoyl Hexapeptide-12, Acetyl Tetrapeptide-11, Acetyl Hexapeptide-8, Acetyl Hexapeptide-1, Palmitoyl Oligopeptide, Acetyl Tetrapeptide-9, Acetyl Tetrapeptide-2, Tripeptide-1, Palmitoyl Tetrapeptide-7, Hexapeptide-11, Dipeptide Diaminobutyroyl Benzylamide Diacetate, Palmitoyl Tripeptide-5, Trifluoroacetyl Tripeptide-2, Palmitoyl Tripeptide-1, Sodium Polyglutamate, Sodium Hyaluronate, Tocopheryl Acetate, Retinyl Palmitate, Ascorbic Acid, Hydrolyzed Soy Protein, Hydrolyzed Wheat Protein, Lecithin, Pseudoalteromonas Ferment Extract, Acrylates Copolymer, Magnesium Chloride, Polysorbate 20, Dimethyl Isosorbide, Acrylates/C10-30 Alkyl Acrylate Crosspolymer, Leuconostoc/Radish Root Ferment Filtrate, PEG-8 Dimethicone, Disodium Phosphate, Carbomer, Dextran, Sodium Lactate, Tetradecyl Aminobutyroylvalylaminobutyric Urea Trifluoroacetate, Xanthan Gum, Triethanolamine, Sodium Phosphate, Octyldodecanol, Silica, Sodium Propoxyhydroxypropyl Thiosulfate Silica, Sodium Hydroxide, Caprylyl Glycol, Potassium Sorbate, Sodium Benzoate, Phenoxyethanol

Alternatives

Ingredients Explained

These ingredients are found in both products.

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

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!

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