Skin science article
Paula's Choice C5 Super Boost Moisturizer Versus Paula's Choice 25% Vitamin C + Glutathione Clinical Serum
Paula's Choice C5 Super Boost Moisturizer Versus Paula's Choice 25% Vitamin C + Glutathione Clinical Serum This brightening moisturizer is formulated around 3-O-Ethyl Ascorbic Acid and Ascorbyl Glucoside to brighten dull-looking skin. This brightening serum is
Paula's Choice C5 Super Boost Moisturizer Versus Paula's Choice 25% Vitamin C + Glutathione Clinical Serum
This brightening moisturizer is formulated around 3-O-Ethyl Ascorbic Acid and Ascorbyl Glucoside to brighten dull-looking skin.
This brightening serum is formulated around Tetrahexyldecyl Ascorbate and Ascorbyl Glucoside to brighten dull-looking skin and fade the look of dark spots.
What's inside
Key Ingredients
Benefits
Concerns
Ingredients Side-by-side
Water
Dicaprylyl Carbonate
3-O-Ethyl Ascorbic Acid
Dimethicone
Butylene Glycol
Polyglyceryl-6 Distearate
Ascorbyl Glucoside
Squalane
Hydroxyethyl Acrylate/Sodium Acryloyldimethyl Taurate Copolymer
Acetyl Sh-Hexapeptide-5 Amide Acetate
Citrullus Lanatus Seed Oil
Hydrogenated Lecithin
Theobroma Cacao Seed Butter
Hydrogenated Phosphatidylcholine
Pentaerythrityl Tetra-Di-T-Butyl Hydroxyhydrocinnamate
Sodium Hyaluronate
Oryza Sativa Bran Extract
Propanediol
Jojoba Esters
Tocopherol
Acetyl Zingerone
Cetyl Palmitate
Caprylyl Glycol
Cetyl Alcohol
Polyglyceryl-3 Beeswax
Sodium Hydroxide
Sorbitan Olivate
Sorbitan Palmitate
Helianthus Annuus Extract
Ethylhexylglycerin
Hexylene Glycol
Sodium Phytate
Polysorbate 60
Sorbitan Isostearate
Lecithin
Rosmarinus Officinalis Leaf Extract
Glycine Soja Oil
Lysolecithin
Bacillus Ferment
Citric Acid
Polyglutamic Acid
Beta-Sitosterol
Phytic Acid
Squalene
Phenoxyethanol
Sodium Benzoate
Potassium Sorbate
Water, Dicaprylyl Carbonate, 3-O-Ethyl Ascorbic Acid, Dimethicone, Butylene Glycol, Polyglyceryl-6 Distearate, Ascorbyl Glucoside, Squalane, Hydroxyethyl Acrylate/Sodium Acryloyldimethyl Taurate Copolymer, Acetyl Sh-Hexapeptide-5 Amide Acetate, Citrullus Lanatus Seed Oil, Hydrogenated Lecithin, Theobroma Cacao Seed Butter, Hydrogenated Phosphatidylcholine, Pentaerythrityl Tetra-Di-T-Butyl Hydroxyhydrocinnamate, Sodium Hyaluronate, Oryza Sativa Bran Extract, Propanediol, Jojoba Esters, Tocopherol, Acetyl Zingerone, Cetyl Palmitate, Caprylyl Glycol, Cetyl Alcohol, Polyglyceryl-3 Beeswax, Sodium Hydroxide, Sorbitan Olivate, Sorbitan Palmitate, Helianthus Annuus Extract, Ethylhexylglycerin, Hexylene Glycol, Sodium Phytate, Polysorbate 60, Sorbitan Isostearate, Lecithin, Rosmarinus Officinalis Leaf Extract, Glycine Soja Oil, Lysolecithin, Bacillus Ferment, Citric Acid, Polyglutamic Acid, Beta-Sitosterol, Phytic Acid, Squalene, Phenoxyethanol, Sodium Benzoate, Potassium Sorbate
Tetrahexyldecyl Ascorbate
Glycerin
C9-12 Alkane
Silica
Pyrus Malus Fruit Extract
Polyglyceryl-6 Polyricinoleate
Acrylates/C10-30 Alkyl Acrylate Crosspolymer
Xanthan Gum
Lysine Carboxymethyl Cysteinate
Coco-Caprylate/Caprate
Glutathione
Sodium Citrate
Helianthus Annuus Seed Extract
Urea
Mannitol
Caprylic/Capric Triglyceride
Sodium PCA
Trehalose
Ascorbic Acid
Glucose
Vanilla Planifolia Fruit Extract
Polyquaternium-51
Ergothioneine
Triacetin
Water, Tetrahexyldecyl Ascorbate, Dimethicone, Glycerin, C9-12 Alkane, Ascorbyl Glucoside, Silica, Pyrus Malus Fruit Extract, Hydrogenated Lecithin, Polyglyceryl-6 Polyricinoleate, Acrylates/C10-30 Alkyl Acrylate Crosspolymer, Xanthan Gum, Oryza Sativa Bran Extract, Hydroxyethyl Acrylate/Sodium Acryloyldimethyl Taurate Copolymer, Cetyl Alcohol, Caprylyl Glycol, Lysine Carboxymethyl Cysteinate, Coco-Caprylate/Caprate, Tocopherol, Glutathione, Sodium Citrate, Sodium Phytate, Hexylene Glycol, Ethylhexylglycerin, Helianthus Annuus Seed Extract, Urea, Mannitol, Caprylic/Capric Triglyceride, Sodium PCA, Rosmarinus Officinalis Leaf Extract, Polysorbate 60, Sorbitan Isostearate, Trehalose, Ascorbic Acid, Glucose, Vanilla Planifolia Fruit Extract, Polyquaternium-51, Ergothioneine, Triacetin, Sodium Hyaluronate, Phenoxyethanol
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Alternatives
Ingredients Explained
These ingredients are found in both products.
Ingredients higher up in an ingredient list are typically present in a larger amount.
Ascorbyl Glucoside (AA-2G) is one of the most stable vitamin C derivatives out there.
It's made by attaching a glucose molecule to ascorbic acid; this glucose "cap" shields the vitamin C from air, light, heat, and metal ions that normally cause pure ascorbic acid to oxidize.
Once on your skin, the enzyme alpha-glucosidase snips off the glucose and gradually releases active ascorbic acid right where it's needed. Basically, it behaves like a slow-release pro-vitamin C with less of a stinging that high-strength ascorbic acid can cause.
The research supports the classic vitamin C benefits as well. In lab and human studies, AA-2G slowed down the skin's production of melanin (the pigment behind dark spots) and helped shield skin cells against sun damage better than ascorbyl phosphate.
These studies also showed AA-2G released vitamin C over a longer period.
A frequently cited manufacturer trial found that a 2% AA-2G face cream significantly improved wrinkle depth and skin roughness after 45 days.
And in 2009, a clinical trial showed it meaningfully lightened dark patches on the gums compared to a placebo.
There's also collagen-synthesis support (since vitamin C is a required cofactor for that) and an antioxidant effect too.
Typical usage is usually between 0.5-5% and most studies/products land around 2%.
AA-2G performs best when formulated at a mildly acidic pH (~5-7) which is much gentler than the pH that pure vitamin C demands (~2.5-3.5).
Just one thing worth knowing: the in-skin conversation rate is only about 55-60% by weight. So a 5% AA-2G product delivers roughly 2.75-3% of actual active vitamin C. On top of that, skin absorption is relatively low because the ingredient is water-soluble.
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).
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.
Hexylene Glycol is a multitasker ingredient that works as a solvent, humectant, emulsifier, viscosity reducer, and preservative booster.
It is able to dissolve both water and oil-soluble ingredients to stabilize tricky actives and make products spread more easily.
As a humectant, it pulls water into the skin. But it's a pretty minor moisturizing ingredient compared to other humectants, like glycerin.
Interestingly, it can act as a mild penetration enhancer. One in vitro study on human skin found a 12% concentration upped the absorption of mometasone furoate (a medicinal ingredient used to treat inflammatory skin conditions) up to 7%.
This ingredient is typically used at levels of 0.1-10% depending on the role it's playing.
A patch test study on eczema patients didn't find a significant increase in irritation versus the control group, but the potential for irritation rises at higher concentrations.
Hydrogenated Lecithin is a more stable version of lecithin.
It's made by taking lecithin (a phospholipid commonly found in soybeans and egg yolks) and hydrogenating it. This just means the unsaturated fatty acids are turned into saturated ones so they don't go bad as easily.
This ingredient is an emollient, emulsifier, and penetration enhancer. As an emollient, it helps soften and hydrate skin by trapping moisture within. As an emulsifier, it prevents oil and water ingredients from separating.
Hydrogenated Lecithin can form tiny spherical structures made of phospholipid bilayers called liposomes. These liposomes are able to capture compounds inside their structure and deliver them through the skin barrier.
Because phospholipids are a natural component of our cell membranes, this ingredient is inherently compatible with skin.
A 2021 study found lecithin-based surfactants were less harsh and more tolerable comared to Sodium Lauryl Sulfate (SLS).
This is a synthetic polymer. It helps improve the texture of products by adding thickness and gel-like feel.
It is also an emulsifer, meaning it prevents ingredients such as oil and water from separating. It also helps evenly disperse other ingredients.
Oryza Sativa Bran Extract comes from the outer layer of a rice kernel. It is a byproduct of milling rice, or the operation to produce a whole grain rice product.
This ingredient has moisturizing properties due to its components of polysaccharides and omega-3 fatty acids. It also contains calcium, selenium, phosphorus, iron, and zinc.
Oryza Sativa Bran Extract contains numerous antioxidants such as ferulic acid. Antioxidants help fight free-radical molecules. Free-radical molecules are capable of damaging our cells and other genetic material.
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 60 is used to help stabilize products. It is a surfactant and emulsifier. These properties help keep ingredients together in a product. Surfactants help reduce surface tension between ingredients with different states, such as liquids and solids. Emulsifiers help prevent oils and waters from separating.
Polysorbate 60 is sorbitol-based and created from the ethoxylation of sorbitan. Ethoxylation is a chemical reaction used to add ethylene oxide. Sorbitan is a the dehydrated version of sorbitol, a sugar found in fruits.
In this case, the 60 comes from reacting 60 units of ethylene oxide with sorbitan.
Polysorbates are commonly used in medicine and foods.
This is a botanical extract from the rosemary plant (the same one you cook with). In skincare, it mostly works as a skin conditioning agent.
Its activity comes from a handful of polyphenols, carnosic acid, carnosol, and rosmarinic acid. Almost 90% of the antioxidant activity of this ingredient can be attributed to canosol and carnosic acid.
These compounds protect your skin two ways:
1) They fight off free radicals, or the unstable molecules from things like sun and pollution that age and damage skin. 2) They help calm inflammation by switching off the chemical signals that tell skin to get red and irritated.
Lab studies also suggest that rosmarinic acid may help protect collagen and slow sugar-related damage to it.
The Cosmetic Ingredient Review has concluded rosemary-derived ingredients to be safe when formulated to be non-sensitizing.
Rosemary can occasionally cause allergic contact dermatitis (due to carnosol), so be sure to patch test if you have reactive or fragrance-sensitive skin.
Sodium Hyaluronate is the salt form of hyaluronic acid. It is a long sugar chain that is naturally found in your skin, joints, and connective tissue that maintains hydration and elasticity.
In skincare, it works as a humectant. It pulls water from the environment and deeper layers of skin and binds it to the surface.
Interestingly, the size of the molecule affects its behavior:
Some clinical evidence links low molecular weight versions to improved wrinkle depth, elasticity, anti-inflammatory effects, and barrier repair.
Many serums use a blend of both weights so you can get surface hydration plus longer-lasting and deeper effects.
You'll typically see concentrations between 0.1-2% for this ingredient.
Sodium Phytate is the synthetic salt form of phytic acid. Phytic acid is an antioxidant and can be found in plant seeds.
Sodium Phytate is a chelating agent. Chelating agents help prevent metals from binding to water. This helps stabilize the ingredients and the product.
Sorbitan Isostearate is an emulsifer. It is created from isostearic acid and sorbitol.
As an emulsifier, it keeps the water and oil ingredients from separating. This keeps formulas stable and smooth.
In a 24 hour occlusive patch test on 56 subjects, 10% sorbitan isostearate was completely non-irritating. Most formulas use less than 10%.
Because it's a fatty acid ester, it may not be fungal acne safe since the Malassezia yeast can utilize it as a nutrient source.
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!