Kiehl's Skin Rescuer Versus Prequel Half & Half Peptides & Ceramides Fluid Moisturizer

Kiehl's Skin Rescuer Versus Prequel Half & Half Peptides & Ceramides Fluid Moisturizer

This calming moisturizer is formulated around Squalane and Centella Asiatica Extract to calm redness and strengthen the skin barrier.

This barrier-repair moisturizer is formulated around Ceramide NP and Hexapeptide-11 to strengthen the skin barrier and soften the look of wrinkles.

What's inside

Key Ingredients

Benefits

Concerns

Ingredients Side-by-side

Water

Glycerin

Squalane

Propanediol

Undecane

Caprylic/Capric Triglyceride

Butyrospermum Parkii Butter

Tridecane

PEG-100 Stearate

Glyceryl Stearate

PEG-20 Stearate

Mannose

Lauroyl Lysine

Cetyl Alcohol

Propylene Glycol

Phenoxyethanol

Ammonium Polyacryloyldimethyl Taurate

Triethanolamine

Carbomer

Tocopherol

P-Anisic Acid

Ectoin

Centella Asiatica Extract

Xanthan Gum

Ceteareth-25

Acetyl Dipeptide-1 Cetyl Ester

Rosa Gallica Flower Extract

Hydroxypalmitoyl Sphinganine

Ceramide NP

Behenic Acid

Cholesterol

Ceramide Ns

Chamomilla Recutita Extract

Ceramide AP

Ceramide EOP

Ceramide Eos

Caprooyl Phytosphingosine

Caprooyl Sphingosine

Citric Acid

Sodium Hydroxide

Water, Glycerin, Squalane, Propanediol, Undecane, Caprylic/Capric Triglyceride, Butyrospermum Parkii Butter, Tridecane, PEG-100 Stearate, Glyceryl Stearate, PEG-20 Stearate, Mannose, Lauroyl Lysine, Cetyl Alcohol, Propylene Glycol, Phenoxyethanol, Ammonium Polyacryloyldimethyl Taurate, Triethanolamine, Carbomer, Tocopherol, P-Anisic Acid, Ectoin, Centella Asiatica Extract, Xanthan Gum, Ceteareth-25, Acetyl Dipeptide-1 Cetyl Ester, Rosa Gallica Flower Extract, Hydroxypalmitoyl Sphinganine, Ceramide NP, Behenic Acid, Cholesterol, Ceramide Ns, Chamomilla Recutita Extract, Ceramide AP, Ceramide EOP, Ceramide Eos, Caprooyl Phytosphingosine, Caprooyl Sphingosine, Citric Acid, Sodium Hydroxide

Isopropyl Myristate

Ethylhexyl Olivate

Hydrolyzed Rice Protein

Ceramide As

Hexapeptide-11

Matrixyl 3000

Polyglyceryl-10 Stearate

Triolein

Ammonium Acryloyldimethyltaurate/Vp Copolymer

Glyceryl Oleate

Hydroxyacetophenone

Glyceryl Dioleate

Caprylyl Glycol

Betaine

Sodium Stearoyl Glutamate

Sodium Phytate

Sodium PCA

Sodium Lactate

PCA

Sodium Benzoate

Serine

Alanine

Palmitic Acid

Glycine

Hydrogenated Lecithin

Ethylhexyl Palmitate

Butylene Glycol

Ethylhexylglycerin

Glutamic Acid

Lysine Hcl

Threonine

Arginine

Proline

Polysorbate 20

Water, Glycerin, Propanediol, Isopropyl Myristate, Ethylhexyl Olivate, Squalane, Hydrolyzed Rice Protein, Ceramide NP, Ceramide As, Ceramide Ns, Ceramide EOP, Ceramide AP, Hexapeptide-11, Matrixyl 3000, Polyglyceryl-10 Stearate, Triolein, Ammonium Acryloyldimethyltaurate/Vp Copolymer, Glyceryl Oleate, Undecane, Hydroxyacetophenone, Glyceryl Dioleate, Caprylyl Glycol, Xanthan Gum, Tridecane, Betaine, Sodium Stearoyl Glutamate, Citric Acid, Sodium Phytate, Sodium PCA, Sodium Hydroxide, Sodium Lactate, PCA, Sodium Benzoate, Serine, Alanine, Palmitic Acid, Glycine, Hydrogenated Lecithin, Ethylhexyl Palmitate, Butylene Glycol, Phenoxyethanol, Ethylhexylglycerin, Glutamic Acid, Lysine Hcl, Threonine, Arginine, Proline, Tocopherol, Carbomer, Polysorbate 20

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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.

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.

Ceramide AP is is a skin-identical lipid that mimics what your skin already makes naturally. Ceramides help maintain epidermal integrity and barrier function.

You'll often see this ingredient paired with other ceramides (like ceramide NP), cholesterol, or fatty acids because this combination best mimics the natural lipid mix your skin already has.

The skin's ability to produce ceramides gets disrupted in skin conditions like eczema. This in turn weakens the skin barrier and applying ceramides topically has been shown to replenish what's been lost to restore barrier function.

Most of the studies with Ceramide AP test it as part of a multi-ceramide complex; studies reinforce ceramide AP's role in rebalancing ceramides in skin and improving skin hydration.

Ceramide EOP is formally known as Ceramide 1.

It is naturally found in skin and part of the intercellular "mortar" holding everything together in your outermost layer.

EOP stands for a linked Ester fatty acid, a linked Omega hydroxy fatty acid, and the Phytosphingosine base.

What makes Ceramide EOP special is its ultra-long fatty acid chain; this unique structure allows it to bridge the lipid layers in your skin barrier to prevent water loss (something no other ceramide can do).

Low levels of Ceramide EOP have been found in people with eczema and psoriasis.

Using it together with other ceramides, cholesterol, and linoleic acid have been shown to meaningfully improve hydration and reduce water loss.

In one clinical study, a regimen using Ceramide EOP, NP, and AP led to significant symptom improvements in patients with eczema, psoriasis, and dry skin in just 4 weeks.

You'll usually see concentrations between 0.1-0.5% in formulations. Overall, this is a well-tolerated and safe ingredient for cosmetic use.

Ceramide NP (formerly known as Ceramide 3) is one of the skin's naturally occurring lipids.

Since ceramides are the major lipid components of the skin, they are crucial for maintaining skin barrier and hydration. Ceramide NP most closely mirrors the dominant kind in human skin amongst ceramide subtypes.

This ceramide works by slotting into gaps within the stratum corneum's lipid matrix to limit trans-epidermal water loss (TEWL) and shield the skin against external irritants.

A study with 312 patients found that using a ceramide-containing routine for 4 weeks reduced the severity of atopic dermatitis by over 61%.

Another clinical study in subjects aged 60 and older found that a ceramide body wash and moisturizer improved skin dryness and itchy skin in 15 days.

Overall, ceramides are considered non-irritating and safety tests have found little to no observable adverse effects from using this ingredient.

Ceramide NP is usually sourced from plants (like soybean or rice bran), or produced synthetically.

Ceramide NS is formally known as Ceramide 2. It is one of the major ceramides in the stratum corneum (outermost layer of skin) plays a role in forming a protective barrier.

Due to its structure, skin lipids can be packed tightly and in turn, this strengthens the barrier and reduces water loss.

Studies show conditions like atopic dermatitis can worsen when ceramide NS levels are low.

Citric Acid is an alpha hydroxy acid (AHA) naturally found in citrus fruits like oranges, lemons, and limes.

Like other AHAs, citric acid can exfoliate skin by breaking down the bonds that hold dead skin cells together. This helps reveal smoother and brighter skin underneath.

However, this exfoliating effect only happens at high concentrations (20%) which can be hard to find in cosmetic products.

Due to this, citric acid is usually included in small amounts as a pH adjuster. This helps keep products slightly more acidic and compatible with skin's natural pH.

In skincare formulas, citric acid can:

While it can provide some skin benefits, research shows lactic acid and glycolic acid are generally more effective and less irritating exfoliants.

Most citric acid used in skincare today is made by fermenting sugars (usually from molasses). This synthetic version is identical to the natural citrus form but easier to stabilize and use in formulations.

Rosacea skin has a lower threshold for acids generally, with 62.5% of rosacea subjects in one study reacting to lactic acid in a sting test. This is why we mark citric acid as a potential rosacea trigger.

However, this ingredient shows up as a pH adjuster or chelator at roughly 0.1-1% in many products. These low levels are unlikely to be an issue for rosacea skin and becomes a potential trigger at exfoliating concentrations (20%). Because everybody's skin is unique, we recommend a patch test if you are unsure.

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.

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.

Propanediol is an all-star ingredient. It softens, hydrates, and smooths the skin.

It’s often used to:

Propanediol is not likely to cause sensitivity and considered safe to use. It is derived from corn or petroleum with a clear color and no scent.

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.

Squalane is the hydrogenated and shelf-stable form of squalene (a lipid that naturally occurs in human sebum).

It is an emollient and skin conditioning agent that is able to integrate seamlessly into the skin's lipid barrier without clogging pores.

This is due to how structurally similar it is to what your skin already produces.

Though it is mostly an emollient that helps soften and hydrate skin, it also has some humectant and occlusive action. Humectants help the skin retain moisture while occlusives seal it in, making squalane a triple-threat moisturizer.

Research shows it has antioxidant capabilities that help protect against stressors like UV exposure, specifically UVA induced oxidative stress. This study also found that it supports collagen biosynthesis in human dermal fibroblasts.

No clinical study has reported significant adverse effects and irritation reactions are very rare from this ingredient (even at 100% concentration).

Overall, it's a fantastic ingredient for hydration and is suitable for all skin types.

This depends on the source. Squalane can be derived from both plants and animals. Most squalane used in skincare comes from plants.

Please note: the source of squalane is only known if disclosed by the brand. We recommend reaching out to the brand if you have any questions about their squalane.

Read more about squalene with an "e".

Though squalane is often called an oil, it’s technically not one. It is a hydrocarbon, meaning it is only made of carbon and hydrogen. True oils are triglycerides and made of fatty acids and glycerol.

The term “oil-free” isn’t regulated so companies can define it however they want. Some exclude all oils, while others just avoid mineral oil or comedogenic oils.

Squalane has a comedogenic rating of 1 from the original 1972 study that tested raw ingredients under occlusion on rabbit ears. This system is not standardized or peer-reviewed, and using the raw ingredients is very different from how diluted cosmetic formulations are used on human skin.

A comedogenic rating of 1 means it is "unlikely to clog pores" according to the original rating system.

The overall formula of a product matters more than the individual ingredients on whether or not it will cause clogged pores.

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.

Tridecane is a lightweight emollient and fragrancing ingredient. It is a paraffin and often called a silicone alternative.

According to official INCI guidelines, this ingredient is used to give a light odor to raw materials. It is often used as a starter ingredient to create parfum.

This ingredient can be derived from palm oil, or coconut oil. It is also naturally found in certain species of organisms.

According to the NOAA, this ingredient can cause skin sensitivity with prolonged use. However, this warning is taken from the Coast Guard and no studies have been done on this in relation to cosmetics.

Tridecane is not water soluble.

Undecane is an emollient and helps create a lightweight base for products.

Is is not soluble in water and naturally occurring in some species.

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!

Xanthan gum is used as a stabilizer and thickener within cosmetic products. It helps give products a sticky, thick feeling - preventing them from being too runny.

On the technical side of things, xanthan gum is a polysaccharide - a combination consisting of multiple sugar molecules bonded together.

Xanthan gum is a pretty common and great ingredient. It is a natural, non-toxic, non-irritating ingredient that is also commonly used in food products.

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