Peptide Skincare & BeautySkin science and ingredient guides

Skin science article

Kiehl's Ultra Facial Cream with Squalane Versus Olehenriksen Strength Trainer Peptide Boost Moisturizer

Kiehl's Ultra Facial Cream with Squalane Versus Olehenriksen Strength Trainer Peptide Boost Moisturizer This barrier-repair moisturizer is formulated around Squalane and Pseudoalteromonas Ferment Extract to strengthen the skin barrier and hydrate skin. This ba

Kiehl's Ultra Facial Cream with Squalane Versus Olehenriksen Strength Trainer Peptide Boost Moisturizer

This barrier-repair moisturizer is formulated around Squalane and Pseudoalteromonas Ferment Extract to strengthen the skin barrier and hydrate skin.

This barrier-repair moisturizer is formulated around Niacinamide and Acetyl Hexapeptide-8 to strengthen the skin barrier and soften the look of wrinkles.

What's inside

Key Ingredients

Benefits

Concerns

Ingredients Side-by-side

Water

Glycerin

Dimethicone

Squalane

Bis-PEG-18 Methyl Ether Dimethyl Silane

Sucrose Stearate

Stearyl Alcohol

PEG-8 Stearate

Myristyl Myristate

Prunus Armeniaca Kernel Oil

Phenoxyethanol

Persea Gratissima Oil

Glyceryl Stearate

Cetyl Alcohol

Oryza Sativa Bran Oil

Olea Europaea Fruit Oil

Chlorphenesin

Stearic Acid

Palmitic Acid

Carbomer

Acrylates/C10-30 Alkyl Acrylate Crosspolymer

Trisodium Ethylenediamine Disuccinate

Prunus Amygdalus Dulcis Oil

Xanthan Gum

Ethylhexylglycerin

Sodium Hydroxide

Tocopherol

Glycine Soja Oil

Pseudoalteromonas Ferment Extract

Myristic Acid

Hydroxypalmitoyl Sphinganine

Salicylic Acid

Helianthus Annuus Seed Oil

Rosmarinus Officinalis Leaf Extract

Citric Acid

Water, Glycerin, Dimethicone, Squalane, Bis-PEG-18 Methyl Ether Dimethyl Silane, Sucrose Stearate, Stearyl Alcohol, PEG-8 Stearate, Myristyl Myristate, Prunus Armeniaca Kernel Oil, Phenoxyethanol, Persea Gratissima Oil, Glyceryl Stearate, Cetyl Alcohol, Oryza Sativa Bran Oil, Olea Europaea Fruit Oil, Chlorphenesin, Stearic Acid, Palmitic Acid, Carbomer, Acrylates/C10-30 Alkyl Acrylate Crosspolymer, Trisodium Ethylenediamine Disuccinate, Prunus Amygdalus Dulcis Oil, Xanthan Gum, Ethylhexylglycerin, Sodium Hydroxide, Tocopherol, Glycine Soja Oil, Pseudoalteromonas Ferment Extract, Myristic Acid, Hydroxypalmitoyl Sphinganine, Salicylic Acid, Helianthus Annuus Seed Oil, Rosmarinus Officinalis Leaf Extract, Citric Acid

Propanediol

Dicaprylyl Carbonate

Methylpropanediol

Cetearyl Alcohol

Mangifera Indica Seed Butter

Niacinamide

Acetyl Hexapeptide-1

Acetyl Hexapeptide-8

Acetyl Octapeptide-3

Acetyl Tetrapeptide-2

Acetyl Dipeptide-1 Cetyl Ester

Palmitoyl Tripeptide-1

Palmitoyl Tetrapeptide-7

Carnosine

Ceramide NP

Ceramide AP

Ceramide EOP

Collagen

Serine

Alanine

Glycine

Glutamic Acid

Lysine Hcl

Threonine

Arginine

Proline

Hyaluronic Acid

Sodium Hyaluronate

Linoleic Acid

Linolenic Acid

Sodium PCA

Sodium Lactate

Panthenol

Tocopheryl Acetate

Betaine

PCA

Cyanocobalamin

Xylitol

Anhydroxylitol

Xylitylglucoside

Sorbitan Olivate

Hydroxyethylcellulose

Cetearyl Olivate

Sorbitan Laurate

Phytosphingosine

Cholesterol

Polysorbate 60

Butylene Glycol

Hydroxyacetophenone

Polysorbate 20

Ammonium Acryloyldimethyltaurate/Beheneth-25 Methacrylate Crosspolymer

Sodium Phytate

Sodium Lauroyl Lactylate

Pentaerythrityl Tetra-Di-T-Butyl Hydroxyhydrocinnamate

Leuconostoc/Radish Root Ferment Filtrate

Caprylyl Glycol

Parfum

Citral

Limonene

Linalool

Water, Propanediol, Dicaprylyl Carbonate, Glycerin, Methylpropanediol, Cetearyl Alcohol, Stearyl Alcohol, Mangifera Indica Seed Butter, Niacinamide, Acetyl Hexapeptide-1, Acetyl Hexapeptide-8, Acetyl Octapeptide-3, Acetyl Tetrapeptide-2, Acetyl Dipeptide-1 Cetyl Ester, Palmitoyl Tripeptide-1, Palmitoyl Tetrapeptide-7, Carnosine, Ceramide NP, Ceramide AP, Ceramide EOP, Collagen, Serine, Alanine, Glycine, Glutamic Acid, Lysine Hcl, Threonine, Arginine, Proline, Hyaluronic Acid, Sodium Hyaluronate, Linoleic Acid, Linolenic Acid, Sodium PCA, Sodium Lactate, Panthenol, Tocopherol, Tocopheryl Acetate, Betaine, PCA, Cyanocobalamin, Xylitol, Anhydroxylitol, Xylitylglucoside, Sorbitan Olivate, Carbomer, Hydroxyethylcellulose, Xanthan Gum, Cetearyl Olivate, Sorbitan Laurate, Phytosphingosine, Cholesterol, Polysorbate 60, Butylene Glycol, Hydroxyacetophenone, Glycine Soja Oil, Acrylates/C10-30 Alkyl Acrylate Crosspolymer, Polysorbate 20, Ammonium Acryloyldimethyltaurate/Beheneth-25 Methacrylate Crosspolymer, Dimethicone, Sodium Phytate, Sodium Lauroyl Lactylate, Pentaerythrityl Tetra-Di-T-Butyl Hydroxyhydrocinnamate, Leuconostoc/Radish Root Ferment Filtrate, Citric Acid, Caprylyl Glycol, Ethylhexylglycerin, Phenoxyethanol, Parfum, Citral, Limonene, Linalool

Reviews

Alternatives

Ingredients Explained

These ingredients are found in both products.

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

Acrylates/C10-30 Alkyl Acrylate Crosspolymer is a synthetic polymer. It is used to thicken, emulsify, and improve the texture of products.

As an emulsifier, it helps stabilize oil-in-water emulsions to give products an elegant feel when applied.

It can also form a thin protective film on skin. One study found that a formula using this polymer helped slow down how quickly other ingredients (like DEET) were absorbed through skin.

A 2024 study of over 1,300 patients confirmed that sensitization to this ingredient is rare. It is also non-mutagenic and has a clean track record.

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.

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.

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.

Glycine Soja Oil is a plant-derived oil from soybean seeds. Like other oils, it is rich in essential fatty acids (mostly linoleic and oleic) that support skin hydration and barrier function.

The fatty acids are able to integrate into the lipid matrix of the stratum corneum to help soften skin and reduce water loss.

On top of that, soybean oil is rich in vitamins like vitamin E, a potent antioxidant.

Research on soybean's active components also point to anti-inflammatory, collagen-stimulating, antioxidant activity, and protection against UV-induced oxidative damage.

Most of this research applies to the broader soybean plant and not just the oil fraction alone.

This ingredient may not be fungal acne safe due to the oleic acid content.

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.

Stearyl Alcohol is a type of fatty alcohol from stearic acid. It is a white, waxy compound used to emulsify ingredients used as an emollient or to thicken a product.

Emollients help soothe and hydrate the skin by trapping moisture.

Fatty alcohols are usually derived from natural fats and oils and therefore do not have the same drying or irritating effect as solvent (ethanol) alcohols.

The FDA allows products labeled "alcohol-free" to have fatty alcohols.

This ingredient may not be fungal acne safe. It is a primary fatty alcohol with a chain length above 12 carbons. A study from 2019 show Malassezia can feed on fatty alcohols in this range, so it may trigger fungal acne in those prone to it.

Tocopherol is a fat-soluble antioxidant known as Vitamin E.

You'll find this ingredient in the vast majority of skincare (for good reason). It works to neutralize free radicals, or unstable molecules generated by UV exposure, pollution, and other environmental stressors, before they can cause oxidative damage to your skin cells.

Topically applied tocopherol has been shown to protect against UV damage by ramping up the skin's own natural defense enzymes.

It also acts as a skin conditioning agent; some studies show that regular topical use can improve the skin's water-binding capacity over 2-4 weeks.

This ingredient is especially loved for being a team player. When combined with Vitamin C, the photoprotective effect of both ingredients roughly doubles and the combo also helps reduce UV-induced DNA damage.

This ingredient has some brightening potential but it's more of a prevention ingredient than spot-fader. Cell studies show it can slow down melanin production but it's worth noting that it's not the most powerful brightener out there.

In formulations, it also serves as a stabilizer that helps protect other oxidation-prone ingredients from degrading.

Concentrations usually range from 0.1-1% in most leave-on products.

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 Side-by-side

  1. 01Water
  2. 02Glycerin
  3. 03Butylene Glycol
  4. 04Dimethicone
  5. 05Pentaerythrityl Tetraethylhexanoate
  6. 06Propanediol
  7. 07Tricaprylin
  8. 08Glyceryl Stearate Se
  9. 09Cetyl Alcohol
  10. 10Silica
  11. 11Myristyl Myristate
  12. 12PEG-100 Stearate
  13. 13Butyrospermum Parkii Butter
  14. 14Copernicia Cerifera Wax
  15. 15Hydrogenated Polyisobutene
  16. 16Hydrogenated Polydecene
  17. 17Behenyl Alcohol
  18. 18Dimethylacrylamide/Sodium Acryloyldimethyltaurate Crosspolymer
  19. 19Isostearic Acid
  20. 20Stearyl Alcohol
Source · skinsort.com
02

Product index

Related product references

03

Comparison edit

Read side by side