Skin science article
Paula's Choice Clinical Ultra-Rich Moisturizer Versus Kiehl's Ultra Facial Cream with Squalane
Paula's Choice Clinical Ultra-Rich Moisturizer Versus Kiehl's Ultra Facial Cream with Squalane This barrier-repair moisturizer is formulated around Butyrospermum Parkii Butter Unsaponifiables and Ceramide NP to strengthen the skin barrier and hydrate skin. Thi
Paula's Choice Clinical Ultra-Rich Moisturizer Versus Kiehl's Ultra Facial Cream with Squalane
This barrier-repair moisturizer is formulated around Butyrospermum Parkii Butter Unsaponifiables and Ceramide NP to strengthen the skin barrier and hydrate skin.
This barrier-repair moisturizer is formulated around Squalane and Pseudoalteromonas Ferment Extract to strengthen the skin barrier and hydrate skin.
What's inside
Key Ingredients
Benefits
Concerns
Ingredients Side-by-side
Water
Butyrospermum Parkii Butter Unsaponifiables
Caprylic/Capric Triglyceride
Glyceryl Stearate Se
Olea Europaea Fruit Oil
Dimethicone
Stearic Acid
Glyceryl Stearate
Mangifera Indica Seed Butter
Cetyl Alcohol
Cocos Nucifera Fruit Extract
Ceramide NP
Ceramide AP
Ceramide EOP
Sphingolipids
Phospholipids
Phytosphingosine
Squalene
Cholesterol
Tocopherol
Simmondsia Chinensis Seed Oil
Persea Gratissima Oil
Glycine Soja Oil
Oryza Sativa Bran Extract
Avena Sativa Kernel Extract
Glycerin
Panthenol
Ascorbyl Palmitate
Beta-Sitosterol
Hydrogenated Vegetable Glycerides Citrate
Propylene Glycol
Sodium Lauroyl Lactylate
Xanthan Gum
Carbomer
Disodium EDTA
Ethylhexylglycerin
Phenoxyethanol
Water, Butyrospermum Parkii Butter Unsaponifiables, Caprylic/Capric Triglyceride, Glyceryl Stearate Se, Olea Europaea Fruit Oil, Dimethicone, Stearic Acid, Glyceryl Stearate, Mangifera Indica Seed Butter, Cetyl Alcohol, Cocos Nucifera Fruit Extract, Ceramide NP, Ceramide AP, Ceramide EOP, Sphingolipids, Phospholipids, Phytosphingosine, Squalene, Cholesterol, Tocopherol, Simmondsia Chinensis Seed Oil, Persea Gratissima Oil, Glycine Soja Oil, Oryza Sativa Bran Extract, Avena Sativa Kernel Extract, Glycerin, Panthenol, Ascorbyl Palmitate, Beta-Sitosterol, Hydrogenated Vegetable Glycerides Citrate, Propylene Glycol, Sodium Lauroyl Lactylate, Xanthan Gum, Carbomer, Disodium EDTA, Ethylhexylglycerin, Phenoxyethanol
Squalane
Bis-PEG-18 Methyl Ether Dimethyl Silane
Sucrose Stearate
Stearyl Alcohol
PEG-8 Stearate
Myristyl Myristate
Prunus Armeniaca Kernel Oil
Oryza Sativa Bran Oil
Chlorphenesin
Palmitic Acid
Acrylates/C10-30 Alkyl Acrylate Crosspolymer
Trisodium Ethylenediamine Disuccinate
Prunus Amygdalus Dulcis Oil
Sodium Hydroxide
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
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.
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.
Cetyl Alcohol is a fatty alcohol. Fatty Alcohols are most often used as an emollient or to thicken a product.
Its main roles are:
Though it has "alcohol" in the name, it is not related to denatured alcohol or ethyl alcohol.
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.
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.
Glyceryl Stearate is made by reacting glycerin with stearic acid (typically sourced from plant oils like palm or coconut). It's an emulsifier, emollient, and mild occlusive.
Emulsifiers help ingredients like oil and water stay mixed so your formula stays nicely blended and uniform in texture.
This ingredient is typically used in concentrations between 1-10%. Studies have found it to be non-sensitizing, non-phototoxic, and non-photoallergenic.
A close cousin of this ingredient is Glyceryl Stearate SE ("self-emulsifying"). This just has a small amount of sodium or potassium stearate added so it can emulsify without a co-emulsifier.
Since this ingredient is an ester of a C18 fatty acid, it may not be fungal acne safe. The Malassezia yeast can potentially metabolize within the C11-C24 range.
Fun fact: The human body also creates Glyceryl Stearate naturally.
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.
This ingredient is also known as olive oil. It has been used in skincare for centuries and science largely backs up its reputation as a nourishing emollient.
The main components of olive oil are oleic acid (55-83%), linoleic acid (3.5-20%), and palmitic acid (7-20%). Oleic acid promotes skin regeneration and helps regulate inflammatory responses.
Squalene is also naturally present in olive oil and exhibits moisturizing and antioxidant properties.
The polyphenols in olive oil also show anti-aging promise; one clinical study found a measurable improvement in skin appearance after 30 days of topical serum use.
Just be aware that applying olive oil directly to skin can weaken the barrier and cause redness. One study with volunteers found even people without sensitive skin experienced a significant reduction in stratum corneum integrity and induced mild erythema.
It's best to use this ingredient as part of a carefully crafted formula (instead of putting it on skin directly from the bottle).
Because it has a 2-3 on the comedogenic scale, it is a moderate risk for acne-prone skin. However, the overall formulation of a product matters more than a few ingredients with comedogenic ratings.
This ingredient may not be fungal acne safe because of the oleic and palmitic acid content. These fall within the C11-24 fatty acid range that the Malassezia yeast can metabolize to grow.
Overall, olive oil is a well-studied and nourishing skincare ingredient.
This ingredient is also known as Avocado oil. It's the cold-pressed oil from the flesh of the avocado fruit packed with fatty acids (mostly oleic acid).
The rich fatty acid profile allows it to function as a skin conditioning agent and emollient; it helps soften and smooth skin while reducing water loss.
Preclinical research has found that topical avocado oil increased collagen synthesis and reduced inflammation during wound healing, giving it some skin-repairing credibility.
The unsaponifiable fraction of the oil is also interesting: studies on avocado unsaponifiables showed that it helped skin produce more collagen and other structural compounds that support healing.
The CIR Expert Panel has found this ingredient to be non-irritating in formulations.
It's a great ingredient for dry or compromised skin. Just know it may not be fungal acne safe. This is because the oleic acid content falls within the range that Malassezia can use as a food source.
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.
Stearic Acid is a fatty acid that is already found in your skin. It's one of the free fatty acids that works alongside ceramides and cholesterols to maintain your barrier.
In cosmetics, it is a multitasker:
Safety-wise, the CIR Expert Panel has concluded it to be safe in cosmetics when formulated to be non-irritating and non-sensitizing.
Free stearic acid is a C18 fatty acid that the Malassezia yeast can substrate, so this ingredient may not be fungal acne safe.
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.