Peptide Skincare & BeautySkin science and ingredient guides

Skin science article

Paula's Choice Resist Intensive Repair Cream Versus Paula's Choice Peptide Booster

Paula's Choice Resist Intensive Repair Cream Versus Paula's Choice Peptide Booster This anti-aging moisturizer is formulated around Retinol and Simmondsia Chinensis Seed Oil to soften the look of wrinkles and hydrate skin. This anti-aging treatment is formulat

Paula's Choice Resist Intensive Repair Cream Versus Paula's Choice Peptide Booster

This anti-aging moisturizer is formulated around Retinol and Simmondsia Chinensis Seed Oil to soften the look of wrinkles and hydrate skin.

This anti-aging treatment is formulated around Tripeptide-1 and Palmitoyl Tripeptide-1 to soften the look of wrinkles and refine skin texture.

What's inside

Key Ingredients

Benefits

Concerns

Ingredients Side-by-side

Water

Ethylhexyl Stearate

Simmondsia Chinensis Seed Oil

Butylene Glycol

Glycerin

Caprylic/Capric Triglyceride

Petrolatum

Cetearyl Alcohol

Dimethicone

Dipentaerythrityl Hexacaprylate/Hexacaprate

Glyceryl Stearate

Tridecyl Trimellitate

PEG-100 Stearate

Phenyl Trimethicone

Retinol

Adenosine

Palmitoyl Tetrapeptide-7

Palmitoyl Hexapeptide-12

Palmitoyl Tripeptide-1

Ceramide Ng

Sodium Hyaluronate

Magnesium Ascorbyl Phosphate

Niacinamide

Tocopherol

Lecithin

Linoleic Acid

Linolenic Acid

Retinyl Palmitate

Glycyrrhiza Glabra Root Extract

Camellia Oleifera Leaf Extract

Citrullus Lanatus Fruit Extract

Lens Esculenta Fruit Extract

Pyrus Malus Fruit Extract

Glycine Soja Sterols

Tribehenin

PEG-10 Phytosterol

Magnesium Aluminum Silicate

Sodium PCA

Sodium Lactate

Pullulan

Xanthan Gum

Sodium Hydroxide

Neopentyl Glycol Dicaprylate/Dicaprate

Cetearyl Glucoside

Tridecyl Stearate

Behenyl Alcohol

Sclerotium Gum

Carbomer

C12-15 Alkyl Benzoate

Polysorbate 20

Disodium EDTA

Sorbic Acid

Phenoxyethanol

Chlorphenesin

Benzoic Acid

Water, Ethylhexyl Stearate, Simmondsia Chinensis Seed Oil, Butylene Glycol, Glycerin, Caprylic/Capric Triglyceride, Petrolatum, Cetearyl Alcohol, Dimethicone, Dipentaerythrityl Hexacaprylate/Hexacaprate, Glyceryl Stearate, Tridecyl Trimellitate, PEG-100 Stearate, Phenyl Trimethicone, Retinol, Adenosine, Palmitoyl Tetrapeptide-7, Palmitoyl Hexapeptide-12, Palmitoyl Tripeptide-1, Ceramide Ng, Sodium Hyaluronate, Magnesium Ascorbyl Phosphate, Niacinamide, Tocopherol, Lecithin, Linoleic Acid, Linolenic Acid, Retinyl Palmitate, Glycyrrhiza Glabra Root Extract, Camellia Oleifera Leaf Extract, Citrullus Lanatus Fruit Extract, Lens Esculenta Fruit Extract, Pyrus Malus Fruit Extract, Glycine Soja Sterols, Tribehenin, PEG-10 Phytosterol, Magnesium Aluminum Silicate, Sodium PCA, Sodium Lactate, Pullulan, Xanthan Gum, Sodium Hydroxide, Neopentyl Glycol Dicaprylate/Dicaprate, Cetearyl Glucoside, Tridecyl Stearate, Behenyl Alcohol, Sclerotium Gum, Carbomer, C12-15 Alkyl Benzoate, Polysorbate 20, Disodium EDTA, Sorbic Acid, Phenoxyethanol, Chlorphenesin, Benzoic Acid

PEG-8 Dimethicone

Tripeptide-1

Myristoyl Hexapeptide-16

Myristoyl Pentapeptide-17

Hexanoyl Dipeptide-3 Norleucine Acetate

Azelaoyl Bis-Dipeptide-10

Glycoproteins

Phospholipids

Dipotassium Glycyrrhizate

Arginine

Valine

Glycine

Alanine

Glutamic Acid

Serine

Threonine

Yeast Extract

Isoleucine

Proline

Histidine

Phenylalanine

PCA

Phytic Acid

Panax Ginseng Root Extract

Psidium Guajava Fruit Extract

Euterpe Oleracea Fruit Extract

Ahnfeltiopsis Concinna Extract

Dextran

Hydrolyzed Silk

Glyceryl Polymethacrylate

C12-16 Pareth-9

Trideceth-12

Aspartic Acid

Caprylyl Glycol

PEG-8

C11-15 Pareth-7

Guar Hydroxypropyltrimonium Chloride

Phytosteryl/Octyldodecyl Lauroyl Glutamate

Ectoin

Citrate Buffer

Trimethylsiloxyamodimethicone

Ethylhexylglycerin

Water, Glycerin, PEG-8 Dimethicone, Tripeptide-1, Palmitoyl Tripeptide-1, Palmitoyl Tetrapeptide-7, Palmitoyl Hexapeptide-12, Myristoyl Hexapeptide-16, Myristoyl Pentapeptide-17, Hexanoyl Dipeptide-3 Norleucine Acetate, Azelaoyl Bis-Dipeptide-10, Glycoproteins, Phospholipids, Adenosine, Dipotassium Glycyrrhizate, Arginine, Valine, Glycine, Alanine, Glutamic Acid, Serine, Threonine, Yeast Extract, Isoleucine, Proline, Histidine, Phenylalanine, PCA, Phytic Acid, Panax Ginseng Root Extract, Sodium PCA, Psidium Guajava Fruit Extract, Euterpe Oleracea Fruit Extract, Ahnfeltiopsis Concinna Extract, Dextran, Hydrolyzed Silk, Lecithin, Glyceryl Polymethacrylate, C12-16 Pareth-9, Trideceth-12, Sodium Lactate, Carbomer, Aspartic Acid, Polysorbate 20, Butylene Glycol, Caprylyl Glycol, PEG-8, C11-15 Pareth-7, Guar Hydroxypropyltrimonium Chloride, Phytosteryl/Octyldodecyl Lauroyl Glutamate, Ectoin, Citrate Buffer, Trimethylsiloxyamodimethicone, Phenoxyethanol, Sodium Hydroxide, Ethylhexylglycerin

Alternatives

Ingredients Explained

These ingredients are found in both products.

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

Adenosine is a purine nucleoside that your body already makes in every cell. In skincare, it acts mainly as a skin conditioning and anti-aging agent.

The way it works is fairly well mapped out:

Your skin has cells called fibroblasts that build collagen (the stuff that keeps skin firm and smooth). Adenosine basically flips a switch on these cells that tells them to get to work making more collagen and other proteins. These cells slow down on their own as skin ages, so Adenosine helps give them a little nudge to keep going.

The clinical backing is pretty solid too.

A blind, randomized, placebo-controlled trial of 126 women aged 45-65 tested a 0.1% cream twice daily and found real improvements in crow's feet and frown lines using a precise 3D skin-mapping technique; these changes showed up by week 3 and held at 2 months.

A later study using Adenosine-loaded dissolving microneedle patches reported gains in wrinkle depth, dermal density, elasticity, and hydration.

On concentrations, South Korea's Ministry of Food and Drug Safety has set 0.04% as the approved functional anti-wrinkle level. You'll typically see this ingredient used somewhere in the 0.04-0.1% range since it works at low doses.

This ingredient has been found safe for cosmetics with the data showing no irritation or sensitization.

Overall, this is a great ingredient for any anti-aging routine and has no photosensitizing effect, so it suits both AM and PM use.

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.

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.

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.

Lecithin is a term for a group of substances found in the cell membranes of plants, animals, and humans. They are made up of phospholipids.

Thanks to its amphiphilic structure (water-loving head and oil-loving tail), it is a true multitasker:

It plays well with most ingredients and is typically used at 0.1-1%. However, concentrations up to 50% have been reported in moisturizers.

Palmitoyl Hexapeptide-12 is a synthetic lipopeptide. This just means it's a short chain of six amino acids with a palmitic acid molecule attached to one end.

The palmitoyl group increases the lipophilicity, helping it penetrate the lipid-rich outer layer of skin more effectively.

Once inside, it helps with keeping skin springy and firm. It works by mimicking the skin repair signals your skin naturally sends out when it's damaged and telling it to kick into rebuild mode.

Studies have shown it can help strengthen the skin barrier as well so it's useful beyond just anti-aging.

In vitro studies suggest it can switch on genes that help skin cells grow, move around, and rebuild skin structure. Just keep in mind most of the strong evidence is from lab studies rather than large-scale clinical trials.

Lab studies suggest it can switch on genes that help skin cells grow, move around, and rebuild skin structure.

This ingredient is usually used at very low concentrations (0.002% in leave-on products).

Fungal acne note: Usually a palmitic acid component can feed Malassezia in unbound form, but here is is covalently bonded to the peptide. This means it is very difficult for Malassezia to access, and therefore very unlikely to cause fungal acne.

Palmitoyl Tetrapeptide-7 (formerly Palmitoyl Tetrapeptide-3) is a synthetic peptide. Its main job is to fight what researchers call "inflammaging".

"Inflammaging" is the slow, low-grade chronic inflammation that quietly breaks down collagen as we age.

This ingredient calms down a specific inflammation signal in your skin cells (called IL-6). When left unchecked, this signal triggers enzymes that break down collagen and elastin.

Clinical testing showed statistically significant improvements in:

Studies also found the more of this ingredient used, the more your skin produces Collagen I, fibronectin, and hyaluronic acid.

You'll likely see this ingredient paired with Palmitoyl Tripeptide-1 in the well-known Matrixyl 3000 complex for enhanced anti-aging effects.

A 3% concentration applied twice daily for two months showed meaningful skin rejuvenation results in clinical panels.

Palmitoyl Tripeptide-1 (aka Pal-GHK) is a synthetic signal peptide made of three amino acids attached to palmitic acid.

That fatty acid attachment is the key: it boosts the peptide's ability to penetrate the skin barrier. This puts it closer to the dermal cells where it can actually make a difference.

Once there, it acts as a matrikine, a signaling peptide that prompts fibroblasts to produce more collagen, fibronectin, and hyaluronic acid.

In vitro studies show it can boost collagen production in skin cells even when UV-damaged skin samples were treated with it at a tiny concentration (it almost fully restored dermal collagen at 5ppm). It achieved this at 100x lower concentration than retinoic acid, which needed 500 ppm to do the same thing.

Human clinical data is promising, but modest:

A study of 23 female volunteers found a small but statistically significant increase (~4%) in skin thickness after treatment at 4 ppm.

A separate small trial of 15 women showed statistically significant reductions in wrinkle length, depth, and skin roughness after applying it twice daily for four weeks.

You'll likely see Pal-GHK paired with Palmitoyl Tetrapeptide-7 as part of the Matrixyl 3000 complex.

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.

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.

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.

Sodium Lactate is the sodium salt of lactic acid, an AHA. It is a humectant and sometimes used to adjust the pH of a product.

This ingredient is part of our skin's NMF, or natural moisturizing factor. Our NMF is essential for the hydration of our top skin layers and plasticity of skin. NMF also influences our skin's natural acid mantle and pH, which protects our skin from harmful bacteria.

High percentages of Sodium Lactate can have an exfoliating effect.

Fun fact: Sodium Lactate is produced from fermented sugar.

Sodium PCA (the salt of PCA) is one of the most well-established humectants in skincare.

Why is it so special? Your skin already makes it naturally; it's a natural component of your skin's Natural Moisturizing Factor (NMF), or the mix of water-binding compounds inside your skin cells that keeps things soft and hydrated.

As a cosmetic ingredient, it grabs water and holds it in the upper layers of skin to smooth roughness and ease dehydration.

There's some clinical support for the NMF approach with a study showing that a cream built to mimic the skin's NMF significantly boosted hydration.

Safety-wise, this ingredient non-irritating, non-comedogenic, and non-phototoxic in testing, with minimal skin absorption.

It also works really well with other hydrators like glycerin or hyaluronic acid, and typical usage is somewhere between 0.2-4%.

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!

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. 02Butylene Glycol
  3. 03Polysorbate 20
  4. 04Cetyl Alcohol
  5. 05Salicylic Acid
  6. 06Ammonium Acryloyldimethyltaurate/Vp Copolymer
  7. 07Cyclopentasiloxane
  8. 08Sorbitan Stearate
  9. 09Camellia Sinensis Leaf Extract
  10. 10Lauric Acid
  11. 11Allantoin
  12. 12Glycerin
  13. 13Glycyrrhiza Glabra Root Extract
  14. 14Avena Sativa Kernel Extract
  15. 15Epilobium Angustifolium Extract
  16. 16Dimethicone
  17. 17Xanthan Gum
  18. 18Magnesium Aluminum Silicate
  19. 19PEG-40 Hydrogenated Castor Oil
  20. 20Sodium Hydroxide
Source · skinsort.com
02

Product index

Related product references

03

Comparison edit

Read side by side