Kiehl's Micro-Dose Anti-Aging Retinol Serum with Ceramides and Peptide Versus Youth To The People Retinal + Niacinamide Youth Serum

Kiehl's Micro-Dose Anti-Aging Retinol Serum with Ceramides and Peptide Versus Youth To The People Retinal + Niacinamide Youth Serum

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

This anti-aging serum is formulated around Niacinamide and Retinal to soften the look of wrinkles and refine skin texture.

What's inside

Key Ingredients

Benefits

Concerns

Ingredients Side-by-side

Water

Glycerin

Butylene Glycol

Pentylene Glycol

Niacinamide

Cetyl Alcohol

Isohexadecane

Isononyl Isononanoate

Diisopropyl Sebacate

2-Oleamido-1,3-Octadecanediol

4-T-Butylcyclohexanol

Acetyl Dipeptide-1 Cetyl Ester

Adenosine

Ceramide NP

Hydroxypalmitoyl Sphinganine

Lauroyl Lysine

Octyldodecanol

Pentaerythrityl Tetra-Di-T-Butyl Hydroxyhydrocinnamate

Sodium Chloride

Sodium Hyaluronate

Sodium Hydroxide

Trisodium Ethylenediamine Disuccinate

Retinol

Tocopherol

Dicaprylyl Ether

Ammonium Polyacryloyldimethyl Taurate

Behenyl Alcohol

Caprylyl Glycol

Carbomer

Cetearyl Alcohol

Cetearyl Glucoside

Glycine Soja Oil

Helianthus Annuus Seed Oil

Hydroxyethylcellulose

Lecithin

Phenethyl Alcohol

Poloxamer 188

Polycaprolactone

Sorbitan Laurate

Steareth-100

CI 40800

Chlorphenesin

Phenoxyethanol

Water, Glycerin, Butylene Glycol, Pentylene Glycol, Niacinamide, Cetyl Alcohol, Isohexadecane, Isononyl Isononanoate, Diisopropyl Sebacate, 2-Oleamido-1,3-Octadecanediol, 4-T-Butylcyclohexanol, Acetyl Dipeptide-1 Cetyl Ester, Adenosine, Ceramide NP, Hydroxypalmitoyl Sphinganine, Lauroyl Lysine, Octyldodecanol, Pentaerythrityl Tetra-Di-T-Butyl Hydroxyhydrocinnamate, Sodium Chloride, Sodium Hyaluronate, Sodium Hydroxide, Trisodium Ethylenediamine Disuccinate, Retinol, Tocopherol, Dicaprylyl Ether, Ammonium Polyacryloyldimethyl Taurate, Behenyl Alcohol, Caprylyl Glycol, Carbomer, Cetearyl Alcohol, Cetearyl Glucoside, Glycine Soja Oil, Helianthus Annuus Seed Oil, Hydroxyethylcellulose, Lecithin, Phenethyl Alcohol, Poloxamer 188, Polycaprolactone, Sorbitan Laurate, Steareth-100, CI 40800, Chlorphenesin, Phenoxyethanol

Triethylhexanoin

Squalane

Cyclodextrin

Hydrogenated Lecithin

Polyglyceryl-10 Myristate

Grifola Frondosa Fruiting Body Extract

Rubus Chamaemorus Seed Oil

Arginine

Retinal

Withania Somnifera Root Extract

Hordeum Vulgare Extract

Ganoderma Lucidum Stem Extract

Sodium Hyaluronate Crosspolymer

Cucumis Sativus Seed Oil

Lonicera Japonica Flower Extract

Ceramide AP

Phytosphingosine

Cholesterol

Lentinus Edodes Mycelium Extract

Lonicera Caprifolium Flower Extract

Butyrospermum Parkii Oil

Ceramide EOP

Sodium Lauroyl Lactylate

Acrylates/C10-30 Alkyl Acrylate Crosspolymer

Capryloyl Glycerin/Sebacic Acid Copolymer

Xanthan Gum

Hydrolyzed Glycosaminoglycans

Hyaluronic Acid

Hydrolyzed Sodium Hyaluronate

Diheptyl Succinate

Ethylhexylglycerin

Phytosterols

Propanediol

Benzyl Glycol

Raspberry Ketone

Water, Butylene Glycol, Triethylhexanoin, Niacinamide, Squalane, Cyclodextrin, Glycerin, Hydrogenated Lecithin, Polyglyceryl-10 Myristate, Grifola Frondosa Fruiting Body Extract, Rubus Chamaemorus Seed Oil, Arginine, Retinal, Withania Somnifera Root Extract, Helianthus Annuus Seed Oil, Hordeum Vulgare Extract, Ganoderma Lucidum Stem Extract, Sodium Hyaluronate Crosspolymer, Cucumis Sativus Seed Oil, Lonicera Japonica Flower Extract, Ceramide NP, Ceramide AP, Phytosphingosine, Cholesterol, Lentinus Edodes Mycelium Extract, Lonicera Caprifolium Flower Extract, Butyrospermum Parkii Oil, Ceramide EOP, Sodium Lauroyl Lactylate, Acrylates/C10-30 Alkyl Acrylate Crosspolymer, Capryloyl Glycerin/Sebacic Acid Copolymer, Xanthan Gum, Tocopherol, Carbomer, Hydrolyzed Glycosaminoglycans, Sodium Hyaluronate, Hyaluronic Acid, Pentylene Glycol, Hydrolyzed Sodium Hyaluronate, Diheptyl Succinate, Phenoxyethanol, Ethylhexylglycerin, Phytosterols, Propanediol, Benzyl Glycol, Raspberry Ketone

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.

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.

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.

Helianthus Annuus Seed Oil is a plant oil derived from the seeds of a sunflower.

It is rich in fatty acids, primarily linoleic acid and oleic acid. This gives it emollient and skin conditioning properties.

The reason this ingredient is so effective is because it forms a thin film on the skin that reduces transepidermal water loss (TEWL) while supplying linoleic acid to the stratum corneum to improve barrier strength.

The high linoleic acid content is particularly noteworthy for acne-prone skin.

Research suggests that acne-prone skin tends to be deficient in linoleic acid in sebum. Topical application may help replenish this to support a healthier follicular environment and less comedone-promoting sebum.

One randomized study found sunflower seed oil preserved skin barrier integrity in adult volunteers with and without atopic dermatitis (outperforming olive oil).

This ingredient is well-studied, gentle, and an effective emollient suitable for most skin types.

On fungal acne: This ingredient may not be Fungal acne (Malassezia folliculitis) safe. This is because it contains fatty acids with carbon chain lengths in the C11-C24 range.

Niacinamide is a multitasking form of vitamin B3 that strengthens the skin barrier, reduces pores and dark spots, regulates oil, and improves signs of aging.

And the best part? It's gentle and well-tolerated by most skin types, including sensitive and reactive skin.

You might have heard of "niacin flush", or the reddening of skin that causes itchiness. Niacinamide has not been found to cause this.

In very rare cases, some individuals may not be able to tolerate niacinamide at all or experience an allergic reaction to it.

If you are experiencing flaking, irritation, and dryness with this ingredient, be sure to double check all your products as this ingredient can be found in all categories of skincare.

When incorporating niacinamide into your routine, look out for concentration amounts. Typically, 5% niacinamide provides benefits such as fading dark spots. However, if you have sensitive skin, it is better to begin with a smaller concentration.

When you apply niacinamide to your skin, your body converts it into nicotinamide adenine dinucleotide (NAD). NAD is an essential coenzyme that is already found in your cells as "fuel" and powers countless biological processes.

In your skin, NAD helps repair cell damage, produce new healthy cells, support collagen production, strengthen the skin barrier, and fight environmental stressors (like UV and pollution).

Our natural NAD levels start to decline with age, leading to slower skin repair, visible aging, and a weaker skin barrier. By providing your skin niacinamide, you're recharging your skin's NAD levels. This leads to stronger, healthier, and younger looking skin.

Another name for vitamin B3 is nicotinamide. This vitamin is water-soluble and our bodies don't store it. We obtain Vitamin B3 from either food or skincare. Meat, fish, wheat, yeast, and leafy greens contain vitamin B3.

The type of niacinamide used in skincare is synthetically created.

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.

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.

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!

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