E45 Face Hydrating Serum Versus The INKEY List Hyaluronic Acid Serum

E45 Face Hydrating Serum Versus The INKEY List Hyaluronic Acid Serum

This hydrating serum is formulated around Sodium Hyaluronate to hydrate skin and strengthen the skin barrier.

This hydrating serum is formulated around Sodium Hyaluronate and Hyaluronic Acid to hydrate skin and strengthen the skin barrier.

What's inside

Key Ingredients

Benefits

Concerns

No concerns

Ingredients Side-by-side

Water

Propanediol

Butylene Glycol

Sodium Hyaluronate

Hydrolyzed Algin

Sea Water

Chlorella Vulgaris Extract

Glycerin

Carbomer

Sodium Hydroxide

Tetrasodium Glutamate Diacetate

Phenoxyethanol

Hydroxyacetophenone

Water, Propanediol, Butylene Glycol, Sodium Hyaluronate, Hydrolyzed Algin, Sea Water, Chlorella Vulgaris Extract, Glycerin, Carbomer, Sodium Hydroxide, Tetrasodium Glutamate Diacetate, Phenoxyethanol, Hydroxyacetophenone

Ammonium Acryloyldimethyltaurate/Vp Copolymer

Leuconostoc/Radish Root Ferment Filtrate

Hyaluronic Acid

Sodium Lactate

Polysorbate 20

Palmitoyl Tetrapeptide-7

Palmitoyl Tripeptide-1

Water, Propanediol, Sodium Hyaluronate, Glycerin, Butylene Glycol, Phenoxyethanol, Ammonium Acryloyldimethyltaurate/Vp Copolymer, Leuconostoc/Radish Root Ferment Filtrate, Hyaluronic Acid, Carbomer, Sodium Lactate, Polysorbate 20, Palmitoyl Tetrapeptide-7, Palmitoyl Tripeptide-1

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.

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 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.

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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