Peter Thomas Roth FIRMx Collagen Serum Versus Kate Somerville KateCeuticals Firming Serum

Peter Thomas Roth FIRMx Collagen Serum Versus Kate Somerville KateCeuticals Firming Serum

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

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

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

Diisopropyl Sebacate

Isocetyl Stearate

Myristyl Alcohol

Dipalmitoyl Hydroxyproline

Glycine Soja Seed Extract

Adenosine

Ceramide Ng

Pisum Sativum Extract

Tropaeolum Majus Flower/Leaf/Stem Extract

Citrus Aurantifolia Oil

Citrus Aurantium Dulcis Peel Oil

Citrus Paradisi Peel Oil

Mentha Piperita Oil

Zingiber Officinale Root Oil

Citrus Aurantium Bergamia Fruit Oil

Tocopherol

Myristyl Glucoside

Polymethylsilsesquioxane

Polyacrylate-13

Commiphora Mukul Resin Extract

Sucrose Palmitate

Polyisobutene

Ammonium Polyacryloyldimethyl Taurate

Caprylic/Capric Triglyceride

Glyceryl Linoleate

Tocopheryl Acetate

Aminomethyl Propanol

Citral

Limonene

Linalool

Water, Dimethicone, Isohexadecane, Glycerin, Propanediol, Polysilicone-11, Diisopropyl Sebacate, Polysorbate 20, Isocetyl Stearate, Myristyl Alcohol, Dipalmitoyl Hydroxyproline, Glycine Soja Seed Extract, Adenosine, Ceramide Ng, Pisum Sativum Extract, Sodium Hyaluronate, Palmitoyl Tripeptide-5, Tropaeolum Majus Flower/Leaf/Stem Extract, Citrus Aurantifolia Oil, Citrus Aurantium Dulcis Peel Oil, Citrus Paradisi Peel Oil, Mentha Piperita Oil, Zingiber Officinale Root Oil, Citrus Aurantium Bergamia Fruit Oil, Tocopherol, Myristyl Glucoside, Polymethylsilsesquioxane, Polyacrylate-13, Commiphora Mukul Resin Extract, Sucrose Palmitate, Polysorbate 80, Polyisobutene, Ammonium Polyacryloyldimethyl Taurate, Caprylic/Capric Triglyceride, Glyceryl Linoleate, Tocopheryl Acetate, Aminomethyl Propanol, Sorbitan Isostearate, Potassium Sorbate, Citric Acid, Disodium EDTA, Ethylhexylglycerin, Phenoxyethanol, Citral, Limonene, Linalool

Alternatives

Ingredients Explained

These ingredients are found in both products.

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

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.

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.

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.

Palmitoyl Tripeptide-5 is a synthetic signal lipopeptide. This just means it is a three amino acid chain bolted onto a palmitic acid tail so it can slip through the skin's lipid barrier.

This peptide has a "build more, lose less" approach.

It's designed to mimic the collagen-stimulating activity in your skin by copying a snippet of one of your skin's own matrix proteins. This nudges fibroblasts into making more collagen while inhibiting the enzyme that breaks down skin protein.

The manufacturer's in vivo study of 45 volunteers found 1% and 2.5% reduced the appearance of wrinkles by 7% and 12% respectively, after using it twice daily for 84 days.

This is in the expected range for peptides; they're slow and cumulative actives and not overnight fixers.

Typical use levels range from 1-3% and this ingredient gets along with pretty much everything.

On the fungal acne front: Although palmitic acid sits in the chain length that Malassezia can feed on, this ingredient has it locked in an amine bond. This makes it hard for Malassezia to access as a source of food, and therefore fungal acne safe.

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.

Polysorbate 20 is a gentle, water-soluble emulsifier and mild surfactant. It stops oil and water from separating to keep your formulas blended and stable.

It also acts as a mild penetration enhancer by helping active ingredients absorb slightly better.

The common safety discussion around this ingredient involves a manufacturing byproduct called 1,4-dioxane.

Trace amounts can form during production but the EU's Scientific Committee on Consumer Safety has concluded that levels at/below 10 ppm in finished products are safe (commercial products consistently fall within acceptable margins).

True allergic reactions are uncommon and the CIR Expert Panel has confirmed this ingredient to be safe as used in cosmetics.

Because it is derived from lauric acid, it may not be fungal acne safe.

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).

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.

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.

Sorbitan Isostearate is an emulsifer. It is created from isostearic acid and sorbitol.

As an emulsifier, it keeps the water and oil ingredients from separating. This keeps formulas stable and smooth.

In a 24 hour occlusive patch test on 56 subjects, 10% sorbitan isostearate was completely non-irritating. Most formulas use less than 10%.

Because it's a fatty acid ester, it may not be fungal acne safe since the Malassezia yeast can utilize it as a nutrient source.

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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