Skin science article
Peter Thomas Roth PRO Strength Retinoid Peptide Serum Versus Sunday Riley A+ High-Dose Retinol Serum
Peter Thomas Roth PRO Strength Retinoid Peptide Serum Versus Sunday Riley A+ High-Dose Retinol Serum This anti-aging serum is formulated around Hydroxypinacolone Retinoate and Ceramide NP to soften the look of wrinkles and refine skin texture. This anti-aging
Peter Thomas Roth PRO Strength Retinoid Peptide Serum Versus Sunday Riley A+ High-Dose Retinol Serum
This anti-aging serum is formulated around Hydroxypinacolone Retinoate and Ceramide NP to soften the look of wrinkles and refine skin texture.
This anti-aging serum is formulated around Hydroxypinacolone Retinoate and Retinol to soften the look of wrinkles and refine skin texture.
What's inside
Key Ingredients
Benefits
Concerns
Ingredients Side-by-side
C9-12 Alkane
Dimethicone
Isononyl Isononanoate
Dimethyl Isosorbide
Trisiloxane
Cyclopentasiloxane
Polysilicone-11
Coco-Caprylate/Caprate
Caprylic/Capric Triglyceride
Hydroxypinacolone Retinoate
Palmitoyl Hexapeptide-14
Ceramide NP
Helianthus Annuus Seed Extract
Hordeum Vulgare Extract
Cucumis Sativus Extract
Laminaria Ochroleuca Extract
Zingiber Officinale Root Extract
Phytosteryl Canola Glycerides
Sodium Hyaluronate
Sodium PCA
Squalane
Tocopherol
Lecithin
Linoleic Acid
Oleic Acid
Palmitic Acid
Stearic Acid
Hydroxystearic Acid
Triolein
Bisabolol
Ethylhexyl Hydroxystearate
Ethoxydiglycol
Ethylhexylglycerin
Water
Mica
Phenoxyethanol
C9-12 Alkane, Dimethicone, Isononyl Isononanoate, Dimethyl Isosorbide, Trisiloxane, Cyclopentasiloxane, Polysilicone-11, Coco-Caprylate/Caprate, Caprylic/Capric Triglyceride, Hydroxypinacolone Retinoate, Palmitoyl Hexapeptide-14, Ceramide NP, Helianthus Annuus Seed Extract, Hordeum Vulgare Extract, Cucumis Sativus Extract, Laminaria Ochroleuca Extract, Zingiber Officinale Root Extract, Phytosteryl Canola Glycerides, Sodium Hyaluronate, Sodium PCA, Squalane, Tocopherol, Lecithin, Linoleic Acid, Oleic Acid, Palmitic Acid, Stearic Acid, Hydroxystearic Acid, Triolein, Bisabolol, Ethylhexyl Hydroxystearate, Ethoxydiglycol, Ethylhexylglycerin, Water, Mica, Phenoxyethanol
Propanediol
Triheptanoin
Glycerin
Pentylene Glycol
Hexyldecanol
Disiloxane
Cetyl PEG/PPG-10/1 Dimethicone
Diheptyl Succinate
Propylene Carbonate
PPG-24-Glycereth-24
Phenyl Trimethicone
Retinol
Ubiquinone
Honey Extract
Sodium Hyaluronate Crosspolymer
Algae Extract
Zingiber Officinale Extract
Opuntia Ficus-Indica Fruit Extract
Butyrospermum Parkii Butter
Phospholipids
Saccharomyces Cerevisiae Extract
Sodium Acrylates Copolymer
Hydrogenated Polyisobutene
1,2-Hexanediol
4-T-Butylcyclohexanol
Polyglyceryl-10 Stearate
Caprylyl Glycol
Helianthus Annuus Seed Oil
Sorbitol
Cetylhydroxyproline Palmitamide
Benzoic Acid
Dehydroacetic Acid
Sodium Phytate
Glyceryl Polyacrylate
Polysorbate 80
Hydroxyphenyl Propamidobenzoic Acid
Brassica Campestris Sterols
Pvp
Capryloyl Glycerin/Sebacic Acid Copolymer
Sodium Benzoate
Alcohol
Potassium Phosphate
Decyl Glucoside
Hexylene Glycol
Potassium Sorbate
Water, Propanediol, Dimethyl Isosorbide, Triheptanoin, Dimethicone, Glycerin, Pentylene Glycol, Hexyldecanol, Disiloxane, Cetyl PEG/PPG-10/1 Dimethicone, Diheptyl Succinate, Propylene Carbonate, Hydroxypinacolone Retinoate, PPG-24-Glycereth-24, Phenyl Trimethicone, Retinol, Ubiquinone, Honey Extract, Sodium Hyaluronate Crosspolymer, Algae Extract, Zingiber Officinale Extract, Opuntia Ficus-Indica Fruit Extract, Bisabolol, Butyrospermum Parkii Butter, Phospholipids, Saccharomyces Cerevisiae Extract, Lecithin, Sodium Acrylates Copolymer, Hydrogenated Polyisobutene, 1,2-Hexanediol, 4-T-Butylcyclohexanol, Polyglyceryl-10 Stearate, Caprylyl Glycol, Helianthus Annuus Seed Oil, Sorbitol, Cetylhydroxyproline Palmitamide, Polysilicone-11, Benzoic Acid, Dehydroacetic Acid, Sodium Phytate, Glyceryl Polyacrylate, Polysorbate 80, Hydroxyphenyl Propamidobenzoic Acid, Stearic Acid, Brassica Campestris Sterols, Pvp, Capryloyl Glycerin/Sebacic Acid Copolymer, Sodium Benzoate, Alcohol, Potassium Phosphate, Decyl Glucoside, Phenoxyethanol, Hexylene Glycol, Potassium Sorbate, Tocopherol
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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.
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.
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.
Dimethyl Isosorbide (often shortened to DMI) is a sugar-derived solvent made from sorbitol. It's used to dissolve tricky ingredients and help them mix smoothly into a formula.
Many actives sit as gritty crystals when undissolved, so DMI swoops in to full dissolve them. This helps improve texture, stability, and how evenly an active is distributed.
It does have a penetration-enhancing reputation that is a bit more nuanced than marketing suggests; a cell study on human skin found that 10% DMI didn't significantly boost the permeation of Hydroquinone, Salicylic Acid, or Octadecenedioic Acid compared to controls (though it did improve their solubility in the formula itself).
Typical usage concentrations usually range from 1-10% depending on the formula's needs; this ingredient is also well tolerated at these levels.
Hydroxypinacolone Retinoate (aka Granactive Retinoid or HPR) is a retinoid that is part of the same vitamin A family as retinol.
It is an ester of retinoic acid that binds directly to your skin's retinoic acid receptors so it doesn't need your skin to convert it through several steps before it can do anything.
In practice, this means it does the classic retinoid jobs in a formula:
The best part is that it can do all this with noticeably less redness, flaking, and stinging than traditional retinoids.
That gentle reputation is backed by lab work as well; a 2018 study on skin models found that HPR triggered higher retinoid-gene activity than retinol, retinal, or retinyl propionate at the same concentrations while being less irritating to cells.
It also boosted procollagen production to levels similar to retinoic acid itself.
A 2023 study showed HPR works synergistically with retinyl propionate to switch on collagen-building pathways and a 2025 clinical serum study in women with mild photoaging saw improvements in wrinkles and elasticity (though that formula also contained retinol, peptides, and Silybin).
One naming quirk worth mentioning:
You'll likely see this ingredient sold under the trade name "Granactive Retinoid", which is actually only 10% HPR blended with 90% Dimethyl Isosorbide solvent. This means a 5% Granactive Retinoid really only means about 0.5% HPR.
Finished products typically land somewhere between 0.05-1% and it's happiest formulated at a mildly acidic to neutral pH (~5.5-6.5).
Another perk is that this is one of the more light- and temperature-stable retinoids which is a nice bonus for shelf life.
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.
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.
Polysilicone-11 is a film-forming silicone that creates a non-tacky and matte finish on the skin. It's commonly used to improve texture, absorb excess oil, and help active ingredients spread evenly.
Due to its "rubber-like" structure, it stays on the skin's surface instead of being absorbed. On the skin, it creates a flexible layer that enhances wearability and stability.
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!