Peter Thomas Roth FIRMx Collagen Serum Versus Kate Somerville Wrinkle Warrior™ 2-in-1 Plumping Moisturizer + Serum

Peter Thomas Roth FIRMx Collagen Serum Versus Kate Somerville Wrinkle Warrior™ 2-in-1 Plumping Moisturizer + Serum

This anti-aging serum is formulated around Palmitoyl Tripeptide-5 to soften the look of wrinkles.

This anti-aging serum is formulated around Hydrolyzed Hyaluronic Acid and Polyglutamic Acid to soften the look of wrinkles and hydrate skin.

What's inside

Key Ingredients

Benefits

Concerns

Ingredients Side-by-side

Collagen

Water

Dimethicone

Butylene Glycol

Polysilicone-11

Glycerin

Caffeine

Squalane

Soluble Collagen

Collagen Amino Acids

Hydrolyzed Collagen

Palmitoyl Dipeptide-5 Diaminobutyroyl Hydroxythreonine

Palmitoyl Tripeptide-5

Acetyl Tetrapeptide-2

Sodium Hyaluronate

Hydroxyproline

Sodium Citrate

Citric Acid

Acrylamide/Sodium Acryloyldimethyltaurate Copolymer

Ammonium Acryloyldimethyltaurate/Vp Copolymer

Hydroxystearic Acid

Magnesium Chloride

Polysorbate 20

Polysorbate 80

Sodium Hydroxide

Sorbitan Isostearate

Decyl Glucoside

Lauryl Glucoside

Tetradecyl Aminobutyroylvalylaminobutyric Urea Trifluoroacetate

Leuconostoc/Radish Root Ferment Filtrate

Disodium EDTA

Potassium Sorbate

Sodium Benzoate

Isohexadecane

Ethylhexylglycerin

Hexylene Glycol

Caprylyl Glycol

Phenoxyethanol

Mica

Collagen, Water, Dimethicone, Butylene Glycol, Polysilicone-11, Glycerin, Caffeine, Squalane, Soluble Collagen, Collagen Amino Acids, Hydrolyzed Collagen, Palmitoyl Dipeptide-5 Diaminobutyroyl Hydroxythreonine, Palmitoyl Tripeptide-5, Acetyl Tetrapeptide-2, Sodium Hyaluronate, Hydroxyproline, Sodium Citrate, Citric Acid, Acrylamide/Sodium Acryloyldimethyltaurate Copolymer, Ammonium Acryloyldimethyltaurate/Vp Copolymer, Hydroxystearic Acid, Magnesium Chloride, Polysorbate 20, Polysorbate 80, Sodium Hydroxide, Sorbitan Isostearate, Decyl Glucoside, Lauryl Glucoside, Tetradecyl Aminobutyroylvalylaminobutyric Urea Trifluoroacetate, Leuconostoc/Radish Root Ferment Filtrate, Disodium EDTA, Potassium Sorbate, Sodium Benzoate, Isohexadecane, Ethylhexylglycerin, Hexylene Glycol, Caprylyl Glycol, Phenoxyethanol, Mica

Propanediol

Dimethyl Isosorbide

Hydrolyzed Vegetable Protein

Polymethylsilsesquioxane

Trehalose

Betaine

Hydrolyzed Hyaluronic Acid

Disodium Acetyl Glucosamine Phosphate

Polyglutamic Acid

Zanthoxylum Bungeanum Fruit Extract

Copper Lysinate/Prolinate

Methylglucoside Phosphate

Chondrus Crispus Extract

Glycine Soja Extract

Aloe Barbadensis Leaf Juice

Adenosine

PEG-12 Dimethicone

Hdi/Trimethylol Hexyllactone Crosspolymer

Oleyl Alcohol

Parfum

Gluconolactone

Benzyl Salicylate

Linalool

Geraniol

Citronellol

Water, Dimethicone, Propanediol, Dimethyl Isosorbide, Hydrolyzed Vegetable Protein, Glycerin, Polysilicone-11, Ammonium Acryloyldimethyltaurate/Vp Copolymer, Butylene Glycol, Polymethylsilsesquioxane, Trehalose, Betaine, Hydrolyzed Hyaluronic Acid, Sodium Hyaluronate, Disodium Acetyl Glucosamine Phosphate, Polyglutamic Acid, Zanthoxylum Bungeanum Fruit Extract, Copper Lysinate/Prolinate, Methylglucoside Phosphate, Chondrus Crispus Extract, Glycine Soja Extract, Aloe Barbadensis Leaf Juice, Adenosine, PEG-12 Dimethicone, Phenoxyethanol, Hdi/Trimethylol Hexyllactone Crosspolymer, Oleyl Alcohol, Decyl Glucoside, Parfum, Ethylhexylglycerin, Disodium EDTA, Gluconolactone, Benzyl Salicylate, Citric Acid, Linalool, Sodium Benzoate, Caprylyl Glycol, Hexylene Glycol, Geraniol, Citronellol

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Ingredients Explained

These ingredients are found in both products.

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

Ammonium Acryloyldimethyltaurate/Vp Copolymer is a synthetically created polymer. It's used as a film-forming agent and used to thicken the consistency of products.

Think of it as a supportive ingredient that helps your gel-creams feel silky, "cloud cream-like", and spread evenly without being greasy.

The Cosmetic Ingredient Review (CIR) Expert Panel evaluated it (along with 22 other acryloyldimethyltaurate polymers) and concluded it's:

Due to its large molecular size, it sits on the surface of skin rather than penetrating it.

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.

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).

Citric Acid is an alpha hydroxy acid (AHA) naturally found in citrus fruits like oranges, lemons, and limes.

Like other AHAs, citric acid can exfoliate skin by breaking down the bonds that hold dead skin cells together. This helps reveal smoother and brighter skin underneath.

However, this exfoliating effect only happens at high concentrations (20%) which can be hard to find in cosmetic products.

Due to this, citric acid is usually included in small amounts as a pH adjuster. This helps keep products slightly more acidic and compatible with skin's natural pH.

In skincare formulas, citric acid can:

While it can provide some skin benefits, research shows lactic acid and glycolic acid are generally more effective and less irritating exfoliants.

Most citric acid used in skincare today is made by fermenting sugars (usually from molasses). This synthetic version is identical to the natural citrus form but easier to stabilize and use in formulations.

Rosacea skin has a lower threshold for acids generally, with 62.5% of rosacea subjects in one study reacting to lactic acid in a sting test. This is why we mark citric acid as a potential rosacea trigger.

However, this ingredient shows up as a pH adjuster or chelator at roughly 0.1-1% in many products. These low levels are unlikely to be an issue for rosacea skin and becomes a potential trigger at exfoliating concentrations (20%). Because everybody's skin is unique, we recommend a patch test if you are unsure.

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.

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.

Disodium EDTA is a chelating agent. It grabs onto and deactivates metal ions that sneak into your products from water, packaging, or air.

This ingredient mainly works behind the scenes and helps with:

On top of that, this ingredient can counteract the effects of hard water by binding to the minerals in it.

One thing worth knowing is that Disodium EDTA has been shown to be a mild penetration enhancer. It can help other ingredients absorb into skin more effectively which can be a double-edged sword (great for actives, but can also make the active too strong if you have sensitive skin).

Clinical patch testing showed no significant skin irritation at typical use concentrations and minimal dermal absorption.

You'll most likely see this ingredient near the end of an ingredient list. It's typically found in concentrations less than 1%.

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.

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.

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.

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.

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.

Sodium Hyaluronate is the salt form of hyaluronic acid. It is a long sugar chain that is naturally found in your skin, joints, and connective tissue that maintains hydration and elasticity.

In skincare, it works as a humectant. It pulls water from the environment and deeper layers of skin and binds it to the surface.

Interestingly, the size of the molecule affects its behavior:

Some clinical evidence links low molecular weight versions to improved wrinkle depth, elasticity, anti-inflammatory effects, and barrier repair.

Many serums use a blend of both weights so you can get surface hydration plus longer-lasting and deeper effects.

You'll typically see concentrations between 0.1-2% for this ingredient.

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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