Skin science article
Paula's Choice 1% Retinol Treatment Versus SkinBetter Science Intensive AlphaRet Overnight Cream
Paula's Choice 1% Retinol Treatment Versus SkinBetter Science Intensive AlphaRet Overnight Cream This anti-aging treatment is formulated around Retinol and Tetrahexyldecyl Ascorbate to soften the look of wrinkles and refine skin texture. This anti-aging treatm
Paula's Choice 1% Retinol Treatment Versus SkinBetter Science Intensive AlphaRet Overnight Cream
This anti-aging treatment is formulated around Retinol and Tetrahexyldecyl Ascorbate to soften the look of wrinkles and refine skin texture.
This anti-aging treatment is formulated around Glycolic Acid and Tetrahexyldecyl Ascorbate to soften the look of wrinkles and refine skin texture.
What's inside
Key Ingredients
Benefits
Concerns
Ingredients Side-by-side
Water
Dimethicone
Glycerin
Butylene Glycol
Isononyl Isononanoate
Castor Isostearate Succinate
Glyceryl Stearate
C12-15 Alkyl Benzoate
Dimethicone Crosspolymer
PEG-33
Polysorbate 20
Behenyl Alcohol
PEG-100 Stearate
Pentaerythrityl Tetraisostearate
Polymethylsilsesquioxane
Tetrahexyldecyl Ascorbate
Retinol
Ceramide Ng
Palmitoyl Tetrapeptide-7
Palmitoyl Hexapeptide-12
Sodium Hyaluronate
Dipotassium Glycyrrhizate
Glycyrrhiza Glabra Root Extract
Avena Sativa Kernel Extract
Arctium Lappa Seed Oil
Salix Alba Extract
Glycine Soja Sterols
Lecithin
Allantoin
Tocopheryl Acetate
Hydrolyzed Soy Protein
Sorbitan Laurate
Acetyl Dipeptide-1 Cetyl Ester
Disodium EDTA
Hydroxyethylcellulose
Palmitoyl Tripeptide-1
Sodium Hydroxide
Tribehenin
Caprylyl Glycol
Ethylhexylglycerin
Pentylene Glycol
PEG-75 Shea Butter Glycerides
PPG-12/Smdi Copolymer
PEG-10 Phytosterol
PEG-8 Dimethicone
PEG-14
Magnesium Aluminum Silicate
Arachidyl Glucoside
Arachidyl Alcohol
Sclerotium Gum
Carbomer
Phenoxyethanol
Benzoic Acid
Water, Dimethicone, Glycerin, Butylene Glycol, Isononyl Isononanoate, Castor Isostearate Succinate, Glyceryl Stearate, C12-15 Alkyl Benzoate, Dimethicone Crosspolymer, PEG-33, Polysorbate 20, Behenyl Alcohol, PEG-100 Stearate, Pentaerythrityl Tetraisostearate, Polymethylsilsesquioxane, Tetrahexyldecyl Ascorbate, Retinol, Ceramide Ng, Palmitoyl Tetrapeptide-7, Palmitoyl Hexapeptide-12, Sodium Hyaluronate, Dipotassium Glycyrrhizate, Glycyrrhiza Glabra Root Extract, Avena Sativa Kernel Extract, Arctium Lappa Seed Oil, Salix Alba Extract, Glycine Soja Sterols, Lecithin, Allantoin, Tocopheryl Acetate, Hydrolyzed Soy Protein, Sorbitan Laurate, Acetyl Dipeptide-1 Cetyl Ester, Disodium EDTA, Hydroxyethylcellulose, Palmitoyl Tripeptide-1, Sodium Hydroxide, Tribehenin, Caprylyl Glycol, Ethylhexylglycerin, Pentylene Glycol, PEG-75 Shea Butter Glycerides, PPG-12/Smdi Copolymer, PEG-10 Phytosterol, PEG-8 Dimethicone, PEG-14, Magnesium Aluminum Silicate, Arachidyl Glucoside, Arachidyl Alcohol, Sclerotium Gum, Carbomer, Phenoxyethanol, Benzoic Acid
Glycolic Acid
Sodium Glycolate
Cetearyl Olivate
Cyclopentasiloxane
Isohexadecane
Sorbitan Olivate
Ceresin
Glycol Palmitate
Niacinamide
Squalane
Methyl Gluceth-20
Ethyl Lactyl Retinoate
Ceramide NP
Hyaluronic Acid
Ubiquinone
Tocopherol
Bisabolol
Superoxide Dismutase
Butyrospermum Parkii Butter
Allantoin Glycyrrhetinic Acid
Sodium PCA
Panthenol
Camellia Sinensis Leaf Extract
Portulaca Oleracea Extract
Linoleic Acid
Cholesterol
Linolenic Acid
Dimethyl Isosorbide
Steareth-2
Acacia Senegal Gum
Xanthan Gum
Hydrated Silica
Tromethamine
CI 77891
Water, Glycolic Acid, Sodium Glycolate, Cetearyl Olivate, Pentylene Glycol, Cyclopentasiloxane, Isohexadecane, Sorbitan Olivate, Tetrahexyldecyl Ascorbate, Glycerin, Ceresin, Glycol Palmitate, Butylene Glycol, Niacinamide, Squalane, Methyl Gluceth-20, Ethyl Lactyl Retinoate, Palmitoyl Tripeptide-1, Palmitoyl Tetrapeptide-7, Ceramide NP, Hyaluronic Acid, Ubiquinone, Tocopherol, Bisabolol, Tocopheryl Acetate, Superoxide Dismutase, Butyrospermum Parkii Butter, Allantoin Glycyrrhetinic Acid, Sodium PCA, Panthenol, Camellia Sinensis Leaf Extract, Portulaca Oleracea Extract, Linoleic Acid, Cholesterol, Linolenic Acid, Magnesium Aluminum Silicate, Dimethyl Isosorbide, Dimethicone, Glyceryl Stearate, PEG-100 Stearate, Steareth-2, Hydroxyethylcellulose, Acacia Senegal Gum, Xanthan Gum, Hydrated Silica, Carbomer, Polysorbate 20, Tromethamine, Disodium EDTA, Ethylhexylglycerin, Phenoxyethanol, CI 77891
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.
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.
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.
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.
Hydroxyethylcellulose is used to improve the texture of products. It is created from a chemical reaction involving ethylene oxide and alkali-cellulose. Cellulose is a sugar found in plant cell walls and help give plants structure.
This ingredient helps stabilize products by preventing ingredients from separating. It can also help thicken the texture of a product.
This ingredient can also be found in pill medicines to help our bodies digest other ingredients.
Magnesium Aluminum Silicate is a type of silica. It comes from naturally occuring minerals such as silicate ores and clay.
Magnesium aluminum silicate is used for enhancing texture and as an absorbent. Due to its large molecular size, it is unable to be absorbed into the skin.
Like other types of silica, this ingredient can be used to thicken a product. As an absorbent, it may be used to absorb extra water or help prevent clumping.
Although “aluminum” in an ingredient name can raise red flags for some consumers, the form and usage context matter significantly. For typical topical applications, there is no substantial evidence of health risks - such as cancer, neurotoxicity, or systemic “aluminum overload.”
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.
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 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.
Peg-100 Stearate is an emollient and emulsifier. As an emollient, it helps keep skin soft by trapping moisture in. On the other hand, emulsifiers help prevent oil and water from separating in a product.
PEGS are a hydrophilic polyether compound . There are 100 ethylene oxide monomers in Peg-100 Stearate. Peg-100 Stearate is polyethylene glycol ester of stearic acid.
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.
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.
Tetrahexyldecyl Ascorbate (THD) is a stable and oil-soluble form of Vitamin C.
THD is special in that it has the ability to travel deeper into skin than traditional ascorbic acid while maintaining the same skin benefits (double win!).
Because it’s oil-soluble, THD dives deep into your skin’s fatty layers (think ceramides and cholesterol) to fight off the kind of free radicals that mess with your skin barrier. This makes it a great pair with water-based vitamin C (ascorbic acid) that mainly works on the surface.
Even at just 0.1%, THD is already showing great antioxidant activity. When used up to 2%, it helps keep your skin happy and calm, especially when it’s stressed from pollution or sun.
Want to fade dark spots or tackle hyperpigmentation? You’ll want 5% or more. Pairing it with brightening buddies like niacinamide or licorice root gives even better results. One study even used 30% THD with other brighteners and saw real results on stubborn discoloration, even in melasma-prone skin.
A note on THD: It’s has a slightly silky, oily texture and usually shows up colorless or pale yellow (though the exact shade can vary by supplier).
While you can sneak it into water-based formulas, it really shines when paired with silicones or oils, which help your skin soak it up better.
THD is pretty stable, but it’s still vulnerable to degradation like ascorbic acid. Too much light or heat (above 113°F / 45°C) can break it down over time. Go for dark and opaque packaging that keeps it safe and shady!
Read more about other types of Vitamin C:
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!