Peptide Skincare & BeautySkin science and ingredient guides

Skin science article

Allies of Skin Peptides & Omegas Firming Eye Cream Versus U beauty The Return Eye Concentrate

Allies of Skin Peptides & Omegas Firming Eye Cream Versus U beauty The Return Eye Concentrate This anti-aging eye moisturizer is formulated around Squalane and Bakuchiol to soften the look of wrinkles and strengthen the skin barrier. This anti-aging eye moistu

Allies of Skin Peptides & Omegas Firming Eye Cream Versus U beauty The Return Eye Concentrate

This anti-aging eye moisturizer is formulated around Squalane and Bakuchiol to soften the look of wrinkles and strengthen the skin barrier.

This anti-aging eye moisturizer is formulated around Squalane and Ceramide NP to soften the look of wrinkles and hydrate skin.

What's inside

Key Ingredients

Benefits

Concerns

Ingredients Side-by-side

Water

Glycerin

Tribehenin

Caprylic/Capric Triglyceride

Isodecyl Neopentanoate

Glyceryl Stearate

Propanediol

Squalane

Acrylamide/Sodium Acryloyldimethyltaurate Copolymer

Leuconostoc/Radish Root Ferment Filtrate

Caprylyl Glycol

Bakuchiol

Sodium Ascorbyl Phosphate

Ceramide NP

Rosa Canina Seed Oil

Adansonia Digitata Seed Oil

Argania Spinosa Kernel Oil

Glycyrrhiza Glabra Root Extract

Pfaffia Paniculata Root Extract

Ptychopetalum Olacoides Bark/Stem Extract

Calanthe Discolor Extract

Lilium Candidum Flower Extract

Ubiquinone

Superoxide Dismutase

Ergothioneine

Tocopheryl Acetate

Bisabolol

Allantoin

Biotin

Hesperidin Methyl Chalcone

Methylglucoside Phosphate

Copper Lysinate/Prolinate

Palmitoyl Tetrapeptide-7

Chrysin

Gluconolactone

Dipeptide-2

Palmitoyl Tripeptide-1

N-Prolyl Palmitoyl Tripeptide-56 Acetate

Calcium Gluconate

N-Hydroxysuccinimide

Caprylyl/Capryl Glucoside

Citric Acid

Glyceryl Polyacrylate

Isohexadecane

Pentylene Glycol

Polysorbate 80

Sodium Citrate

Sodium Gluconate

Sodium Hydroxide

Sorbitan Oleate

Steareth-20

Xanthan Gum

Benzyl Alcohol

Chlorhexidine Digluconate

Sodium Benzoate

Potassium Sorbate

Phenoxyethanol

Water, Glycerin, Tribehenin, Caprylic/Capric Triglyceride, Isodecyl Neopentanoate, Glyceryl Stearate, Propanediol, Squalane, Acrylamide/Sodium Acryloyldimethyltaurate Copolymer, Leuconostoc/Radish Root Ferment Filtrate, Caprylyl Glycol, Bakuchiol, Sodium Ascorbyl Phosphate, Ceramide NP, Rosa Canina Seed Oil, Adansonia Digitata Seed Oil, Argania Spinosa Kernel Oil, Glycyrrhiza Glabra Root Extract, Pfaffia Paniculata Root Extract, Ptychopetalum Olacoides Bark/Stem Extract, Calanthe Discolor Extract, Lilium Candidum Flower Extract, Ubiquinone, Superoxide Dismutase, Ergothioneine, Tocopheryl Acetate, Bisabolol, Allantoin, Biotin, Hesperidin Methyl Chalcone, Methylglucoside Phosphate, Copper Lysinate/Prolinate, Palmitoyl Tetrapeptide-7, Chrysin, Gluconolactone, Dipeptide-2, Palmitoyl Tripeptide-1, N-Prolyl Palmitoyl Tripeptide-56 Acetate, Calcium Gluconate, N-Hydroxysuccinimide, Caprylyl/Capryl Glucoside, Citric Acid, Glyceryl Polyacrylate, Isohexadecane, Pentylene Glycol, Polysorbate 80, Sodium Citrate, Sodium Gluconate, Sodium Hydroxide, Sorbitan Oleate, Steareth-20, Xanthan Gum, Benzyl Alcohol, Chlorhexidine Digluconate, Sodium Benzoate, Potassium Sorbate, Phenoxyethanol

Pentaerythrityl Tetraethylhexanoate

Butylene Glycol

Behenyl Alcohol

Dimethicone

Dipropylene Glycol

Diphenylsiloxy Phenyl Trimethicone

Beheneth-25

Cera Microcristallina

Trehalose

Bis-PEG-18 Methyl Ether Dimethyl Silane

Cetearyl Alcohol

Hydrogenated Polyisobutene

Sodium Acrylate/Acryloyldimethyltaurate/Dimethylacrylamide Crosspolymer

Hydrogenated Castor Oil

Stevia Rebaudiana Leaf/Stem Extract

Plankton Extract

Tocopherol

Ascorbyl Palmitate

Linoleic Acid

Oleic Acid

Palmitic Acid

Stearic Acid

Glutathione

Hydrolyzed Hyaluronic Acid

Sodium Hyaluronate

Linolenic Acid

Diamond Powder

Lactobionic Acid

Mandelic Acid

Glycolic Acid

Beta-Glucan

Palmitoyl Pentapeptide-4

Acacia Decurrens/Jojoba/Sunflower Seed Cera/Polyglyceryl-3 Esters

Dipotassium Glycyrrhizate

Myristyl Myristate

Sodium Stearoyl Glutamate

Dimethicone/Phenyl Vinyl Dimethicone Crosspolymer

Polysorbate 60

Hydroxyphenyl Propamidobenzoic Acid

Dimethylmethoxy Chromanyl Palmitate

Methyldihydrojasmonate

Sorbitan Isostearate

Tetrasodium Glutamate Diacetate

Hydroxymethoxyphenyl Decanone

Polymethylsilsesquioxane

Polysorbate 20

Carbomer

Ethylhexylglycerin

Benzoic Acid

Dehydroacetic Acid

Water, Pentaerythrityl Tetraethylhexanoate, Butylene Glycol, Squalane, Glycerin, Behenyl Alcohol, Dimethicone, Dipropylene Glycol, Diphenylsiloxy Phenyl Trimethicone, Beheneth-25, Cera Microcristallina, Trehalose, Bis-PEG-18 Methyl Ether Dimethyl Silane, Cetearyl Alcohol, Hydrogenated Polyisobutene, Pentylene Glycol, Sodium Acrylate/Acryloyldimethyltaurate/Dimethylacrylamide Crosspolymer, Hydrogenated Castor Oil, Stevia Rebaudiana Leaf/Stem Extract, Plankton Extract, Bisabolol, Tocopheryl Acetate, Tocopherol, Ceramide NP, Ascorbyl Palmitate, Sodium Ascorbyl Phosphate, Linoleic Acid, Oleic Acid, Palmitic Acid, Stearic Acid, Glutathione, Superoxide Dismutase, Hydrolyzed Hyaluronic Acid, Sodium Hyaluronate, Linolenic Acid, Diamond Powder, Lactobionic Acid, Mandelic Acid, Glycolic Acid, Beta-Glucan, Palmitoyl Pentapeptide-4, N-Prolyl Palmitoyl Tripeptide-56 Acetate, Acacia Decurrens/Jojoba/Sunflower Seed Cera/Polyglyceryl-3 Esters, Dipotassium Glycyrrhizate, Myristyl Myristate, Isohexadecane, Sodium Stearoyl Glutamate, Dimethicone/Phenyl Vinyl Dimethicone Crosspolymer, Polysorbate 60, Hydroxyphenyl Propamidobenzoic Acid, Dimethylmethoxy Chromanyl Palmitate, Methyldihydrojasmonate, Sorbitan Isostearate, Tetrasodium Glutamate Diacetate, Hydroxymethoxyphenyl Decanone, Polymethylsilsesquioxane, Polysorbate 20, Xanthan Gum, Carbomer, Caprylyl Glycol, Sodium Hydroxide, Citric Acid, Ethylhexylglycerin, Phenoxyethanol, Benzoic Acid, Dehydroacetic 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.

Bisabolol is a gentle skin conditioner, antioxidant, and soothing ingredient.

It's primary claim to fame is soothing and research shows topically applied bisabolol can quiet the chemical messengers that cause your skin to become inflamed, helping to sooth any irritation.

A clinical study found that applying 0.5% bisabolol daily for 8 weeks produced an average 9% decrease in skin pigmentation. Researchers found it can also suppress the process that leads to excess melanin production in skin.

In vitro studies found that bisabolol combined with propylene glycol significantly increased skin permeability by increasing lipid fluidity in the stratum corneum.

You'll likely see use concentrations quite low, usually 0.1-0.2%.

Overall, this is a well-tolerated ingredient that works well in formulas designed for sensitive, reactive, or post-procedure skin.

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).

Ceramide NP (formerly known as Ceramide 3) is one of the skin's naturally occurring lipids.

Since ceramides are the major lipid components of the skin, they are crucial for maintaining skin barrier and hydration. Ceramide NP most closely mirrors the dominant kind in human skin amongst ceramide subtypes.

This ceramide works by slotting into gaps within the stratum corneum's lipid matrix to limit trans-epidermal water loss (TEWL) and shield the skin against external irritants.

A study with 312 patients found that using a ceramide-containing routine for 4 weeks reduced the severity of atopic dermatitis by over 61%.

Another clinical study in subjects aged 60 and older found that a ceramide body wash and moisturizer improved skin dryness and itchy skin in 15 days.

Overall, ceramides are considered non-irritating and safety tests have found little to no observable adverse effects from using this ingredient.

Ceramide NP is usually sourced from plants (like soybean or rice bran), or produced synthetically.

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.

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.

N-Prolyl Palmitoyl Tripeptide-56 Acetate is a peptide.

Pentylene Glycol (1,2-pentanediol) is a multitasking little diol with three main roles in a formula:

Research on alkanediols (the family pentylene glycol belongs to) show they work by disrupting microbial cell membranes. This disruption helps the primary preservative system in a product work more effectively at lower doses.

On the safety side, the Cosmetic Ingredient Review Expert Panel has concluded this ingredient to be safe as used in current cosmetic practices + concentrations.

Typical use levels in a formula run about 1-5%.

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.

Sodium Ascorbyl Phosphate (SAP) is a water-soluble form of Vitamin C. It is the salt of ascorbic acid.

This ingredient is commonly used in skincare because it's more formulation-stable while still offering the same benefits as pure ascorbic acid. Ascorbic acid is notorious for breaking down when exposed to sunlight and oxygen whereas SAP has been shown to be more stable.

Studies show SAP has anti-acne and antioxidant benefits. One study found 5% of SAP lotion to be an effective ingredient for treating acne vulgaris. This is because research shows that SAP may help control acne by reducing acne-causing bacteria and slowing the oxidation of skin oils caused by UV exposure.

In addition to acne, vitamin C is important for skin structure. Lab studies suggest SAP may support collagen production in skin cells, making it a great ingredient in anti-aging routines.

Vitamin C has many benefits: it helps reduce redness, improve skin texture, fade the appearance of dark spots, and brighten the skin.

Read more about other types of Vitamin C:

Sodium Hydroxide is also known as lye or caustic soda. It is used to adjust the pH of products; many ingredients require a specific pH to be effective.

In small amounts, sodium hydroxide is considered safe to use. However, large amounts may cause chemical burns due to its high alkaline.

Your skin has a natural pH and acid mantle. This acid mantle helps prevent harmful bacteria from breaking through. The acid mantle also helps keep your skin hydrated.

"Alkaline" refers to a high pH level. A low pH level would be considered acidic.

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.

Superoxide Dismutase is found in all living cells. This ingredient is AKA as 'SOD'.

SOD is a strong antioxidant. It protects living cells against oxidative damage by breaking down radical molecules into regular oxygen and hydrogen peroxide.

Antioxidants help fight free-radical molecules that may damage your skin's DNA. This may help with the signs of aging. Due to its antioxidant property, it is used to help treat chronic inflammation.

In cosmetics, SOD is usually obtained from marine phytoplankton, bovine liver, horseradish, cantaloupe, and certain bacteria.

The three major families of SOD include: Copper/Zinc, Iron/Manganese, and Nickel.

When eating SOD-rich foods, our bodies break it down into amino acids before absorption. Foods that contain SOD include: melons, citrus, spinach, broccoli, kale, almonds, sunflower seeds, and blue-green algae.

Tocopheryl Acetate is a stable, shelf-friendly form of vitamin E.

Formulators love it because plain vitamin E oxidizes quickly once it hits air. This acetate version stays stable and resists going off, helping to extend a product's shelf life.

It's actually inactive on its own and works like a slow-release "storage" form; the enzymes in your skin called esterases gradually convert it into active vitamin E over time.

One in vivo study showed 5% of the acetate in the living layer of the epidermis converted to vitamin E after 5 days of application. This study also found the skin gained protection against UV damage even though the conversion was slow and small.

Once converted, vitamin E acts as a skin's main fat-soluble antioxidant that fights free radicals to protect skin from damage.

Topical vitamin E generally boosts the skin's photoprotection, and it reduced UV-damage in animal models.

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.

Overall, it has a pretty solid safety profile and has been found to be non-irritating and non-comedogenic. Allergic reactions may happen but stay rare due to how widely the ingredient gets used.

The concentration will vary depending on the formula; industry data shows 0.1% in baby lotions, 3% in lipsticks, and 5% in foot powders. You can also find this ingredient at 100% in a pure vitamin E oil.

Most leave-on skincare keeps it at the lower end, often between 0.5-1%.

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.

02

Product index

Related product references

03

Comparison edit

Read side by side