Peptide Skincare & BeautySkin science and ingredient guides

Skin science article

Kiehl's Fast Release Wrinkle-Reducing 0.3% Retinol Night Serum Versus Peter Thomas Roth PRO Strength Retinoid Peptide Serum

Kiehl's Fast Release Wrinkle-Reducing 0.3% Retinol Night Serum Versus Peter Thomas Roth PRO Strength Retinoid Peptide Serum This anti-aging serum is formulated around Panthenol and Adenosine to soften the look of wrinkles and fade the look of dark spots. This

Kiehl's Fast Release Wrinkle-Reducing 0.3% Retinol Night Serum Versus Peter Thomas Roth PRO Strength Retinoid Peptide Serum

This anti-aging serum is formulated around Panthenol and Adenosine to soften the look of wrinkles and fade the look of dark spots.

This anti-aging serum is formulated around Hydroxypinacolone Retinoate and Ceramide NP to soften the look of wrinkles and refine skin texture.

What's inside

Key Ingredients

Benefits

Concerns

Ingredients Side-by-side

Water

Glycerin

Propanediol

Butylene Glycol

Glycereth-26

Panthenol

1,2-Hexanediol

Polyglycerin-3

C12-14 Pareth-12

Phenoxyethanol

Caprylyl Glycol

Ammonium Acryloyldimethyltaurate/Vp Copolymer

Betaine

Xanthan Gum

Ethylhexylglycerin

Adenosine

Carbomer

Glyceryl Acrylate/Acrylic Acid Copolymer

Tromethamine

Glycereth-25 PCA Isostearate

T-Butyl Alcohol

Tocopherol

Water, Glycerin, Propanediol, Butylene Glycol, Glycereth-26, Panthenol, 1,2-Hexanediol, Polyglycerin-3, C12-14 Pareth-12, Phenoxyethanol, Caprylyl Glycol, Ammonium Acryloyldimethyltaurate/Vp Copolymer, Betaine, Xanthan Gum, Ethylhexylglycerin, Adenosine, Carbomer, Glyceryl Acrylate/Acrylic Acid Copolymer, Tromethamine, Glycereth-25 PCA Isostearate, T-Butyl Alcohol, Tocopherol

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

Lecithin

Linoleic Acid

Oleic Acid

Palmitic Acid

Stearic Acid

Hydroxystearic Acid

Triolein

Bisabolol

Ethylhexyl Hydroxystearate

Ethoxydiglycol

Mica

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

Alternatives

Ingredients Explained

These ingredients are found in both products.

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

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.

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.

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!

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