The INKEY List Hyaluronic Acid Hydrating Hair Treatment Versus Olaplex Nº.9 Bond Protector Nourishing Hair Serum

The INKEY List Hyaluronic Acid Hydrating Hair Treatment Versus Olaplex Nº.9 Bond Protector Nourishing Hair Serum

What's inside

Key Ingredients

Benefits

Concerns

Ingredients Side-by-side

Water

PEG-40 Hydrogenated Castor Oil

Betaine

Panthenol

Phenoxyethanol

Polyquaternium-37

Citronellyl Methylcrotonate

Ethylhexylglycerin

Hydrolyzed Hyaluronic Acid

Trisodium Ethylenediamine Disuccinate

Lactic Acid

Sodium Hyaluronate

Water, PEG-40 Hydrogenated Castor Oil, Betaine, Panthenol, Phenoxyethanol, Polyquaternium-37, Citronellyl Methylcrotonate, Ethylhexylglycerin, Hydrolyzed Hyaluronic Acid, Trisodium Ethylenediamine Disuccinate, Lactic Acid, Sodium Hyaluronate

Propanediol

Quaternium-22

Bis-Aminopropyl Diglycol Dimaleate

Cetrimonium Chloride

Hydroxyethylcellulose

Pvp

Guar Hydroxypropyltrimonium Chloride

Furcellaria Lumbricalis Extract

Pelvetia Canaliculata Extract

Xylitylglucoside

Polyquaternium-44

Anhydroxylitol

Maltitol

Citric Acid

Xylitol

Sodium Hydroxide

Sorbic Acid

Sodium Benzoate

Parfum

Citral

Citronellol

Hexyl Cinnamal

Limonene

Linalool

Water, Propanediol, Betaine, Quaternium-22, Bis-Aminopropyl Diglycol Dimaleate, Sodium Hyaluronate, Cetrimonium Chloride, Panthenol, Hydroxyethylcellulose, Pvp, Guar Hydroxypropyltrimonium Chloride, Furcellaria Lumbricalis Extract, Pelvetia Canaliculata Extract, Xylitylglucoside, Polyquaternium-44, Anhydroxylitol, Maltitol, Citric Acid, Trisodium Ethylenediamine Disuccinate, Xylitol, Ethylhexylglycerin, Sodium Hydroxide, Sorbic Acid, Phenoxyethanol, Sodium Benzoate, Parfum, Citral, Citronellol, Hexyl Cinnamal, Limonene, Linalool

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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.

Betaine is a humectant. Like hyaluronic acid, it helps attract and retain moisture in the skin. It’s known for being gentle and for helping the skin maintain balanced hydration.

Betaine is mainly used to improve hydration and support calmer skin. It helps skin cells regulate water balance because it functions as an osmolyte.

Some studies suggest betaine may support making skin tone more even.

Fun fact: Betaine naturally exists in the skin and the body. In cosmetic products, it can be either plant-derived (most commonly from sugar beets) or synthetically produced for consistency and stability.

Betaine is also known as trimethylglycine.

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.

Panthenol is a common ingredient that helps hydrate and soothe the skin. It is found naturally in our skin and hair.

There are two forms of panthenol: D and L.

D-panthenol is also known as dexpanthenol. Most cosmetics use dexpanthenol or a mixture of D and L-panthenol.

Panthenol is famous due to its ability to go deeper into the skin's layers. Using this ingredient has numerous pros (and no cons):

Like hyaluronic acid, panthenol is a humectant. Humectants are able to bind and hold large amounts of water to keep skin hydrated.

This ingredient works well for wound healing. It works by increasing tissue in the wound and helps close open wounds.

Once oxidized, panthenol converts to pantothenic acid. Panthothenic acid is found in all living cells.

This ingredient is also referred to as pro-vitamin B5.

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.

Trisodium Ethylenediamine Disuccinate is used to help stabilize a product.

It is a chelating agent, meaning it helps prevent metal ions from binding to other ingredients. This prevents unwanted reactions in products. Metal ions can come into a product via the water ingredient. They are found in trace amounts and are not known to be harmful.

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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