The Ordinary Multi-Peptide Serum for Hair Density Versus Olaplex Nº.9 Bond Protector Nourishing Hair Serum
Updated on May 21, 2025
Overview
What they are
These products are both vegan, cruelty-free, and reef safe . They have a total of 6 ingredients in common
Suited For
They're both likely to be good for dry skin, sensitive skin, scar healing and dark spots
Free From
They both do not contain any harsh alcohols, parabens, silicones or sulfates
We independently verify ingredients, and our claims are backed by peer-reviewed research. Spot a product that needs an update? Let us know.
Ingredient Info
The Ordinary Multi-Peptide Serum for Hair Density 36 ingredients
Olaplex Nº.9 Bond Protector Nourishing Hair Serum 31 ingredients
What's inside (and what isn't)
What's inside (and what isn't)
At a glance
Click on any of the items below to learn more
The Ordinary Multi-Peptide Serum for Hair Density 36 ingredients
Olaplex Nº.9 Bond Protector Nourishing Hair Serum 31 ingredients
Key Ingredients
Benefits
Concerns
Benefits
Concerns
Ingredients Side-by-side
Water
Skin ConditioningPropanediol
Solvent
Butylene Glycol
Humectant
Glycerin
Humectant
Caffeine
Skin Conditioning
Biotinoyl Tripeptide-1
Acetyl Tetrapeptide-3
Skin Protecting
Larix Europaea Wood Extract
HumectantPisum Sativum Extract
Skin ConditioningScutellaria Baicalensis Root Extract
AstringentTriticum Vulgare Germ Extract
Skin ConditioningGlycine Soja Germ Extract
EmollientTrifolium Pratense Flower Extract
Astringent
Camellia Sinensis Leaf Extract
Antimicrobial
Apigenin
Antioxidant
Oleanolic Acid
Skin ConditioningArginine
Masking
Glycine
Buffering
Calcium Gluconate
HumectantZinc Chloride
SoothingLactic Acid
Buffering
Gluconolactone
Skin Conditioning
Dextran
Maltodextrin
Absorbent
Hydroxyethylcellulose
Emulsion StabilisingXanthan Gum
EmulsifyingPentylene Glycol
Skin ConditioningDimethyl Isosorbide
SolventPolysorbate 20
Emulsifying
PPG-26-Buteth-26
Skin ConditioningPEG-40 Hydrogenated Castor Oil
Emulsifying
Trisodium Ethylenediamine Disuccinate
Sodium Metabisulfite
Antioxidant
Sodium Benzoate
Masking
Phenoxyethanol
Preservative
Chlorphenesin
Antimicrobial
Water, Propanediol, Butylene Glycol, Glycerin, Caffeine, Biotinoyl Tripeptide-1, Acetyl Tetrapeptide-3, Larix Europaea Wood Extract, Pisum Sativum Extract, Scutellaria Baicalensis Root Extract, Triticum Vulgare Germ Extract, Glycine Soja Germ Extract, Trifolium Pratense Flower Extract, Camellia Sinensis Leaf Extract, Apigenin, Oleanolic Acid, Arginine, Glycine, Calcium Gluconate, Zinc Chloride, Lactic Acid, Gluconolactone, Dextran, Maltodextrin, Hydroxyethylcellulose, Xanthan Gum, Pentylene Glycol, Dimethyl Isosorbide, Polysorbate 20, PPG-26-Buteth-26, PEG-40 Hydrogenated Castor Oil, Trisodium Ethylenediamine Disuccinate, Sodium Metabisulfite, Sodium Benzoate, Phenoxyethanol, Chlorphenesin
Water
Skin ConditioningPropanediol
Solvent
Betaine
Humectant
Quaternium-22
Bis-Aminopropyl Diglycol Dimaleate
Skin ConditioningSodium Hyaluronate
Humectant
Cetrimonium Chloride
Antimicrobial
Panthenol
Skin Conditioning
Hydroxyethylcellulose
Emulsion StabilisingPvp
Emulsion StabilisingGuar Hydroxypropyltrimonium Chloride
Skin ConditioningFurcellaria Lumbricalis Extract
Skin ConditioningPelvetia Canaliculata Extract
Skin ProtectingXylitylglucoside
Humectant
Polyquaternium-44
Anhydroxylitol
Humectant
Maltitol
HumectantCitric Acid
Buffering
Trisodium Ethylenediamine Disuccinate
Xylitol
Humectant
Ethylhexylglycerin
Skin ConditioningSodium Hydroxide
BufferingSorbic Acid
Preservative
Phenoxyethanol
Preservative
Sodium Benzoate
Masking
Parfum
Masking
Citral
Perfuming
Citronellol
Perfuming
Hexyl Cinnamal
Perfuming
Limonene
Perfuming
Linalool
Perfuming
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
Ingredients Explained
These ingredients are found in both products.
Ingredients higher up in an ingredient list are typically present in a larger amount.
Hydroxyethylcellulose is used to improve the texture of products. It is created from a chemical reaction involving ethylene oxide and alkali-cellulose. Cellulose is a sugar found in plant cell walls and help give plants structure.
This ingredient helps stabilize products by preventing ingredients from separating. It can also help thicken the texture of a product.
This ingredient can also be found in pill medicines to help our bodies digest other ingredients.
Learn more about HydroxyethylcellulosePhenoxyethanol is a preservative that has germicide, antimicrobial, and aromatic properties. Studies show that phenoxyethanol can prevent microbial growth. By itself, it has a scent that is similar to that of a rose.
It's often used in formulations along with Caprylyl Glycol to preserve the shelf life of products.
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.
Learn more about PropanediolSodium Benzoate is a preservative. It's used in both cosmetic and food products to inhibit the growth of mold and bacteria. It is typically produced synthetically.
Both the US FDA and EU Health Committee have approved the use of sodium benzoate. In the US, levels of 0.1% (of the total product) are allowed.
Sodium benzoate works as a preservative by inhibiting the growth of bacteria inside of cells. It prevents the cell from fermenting a type of sugar using an enzyme called phosphofructokinase.
It is the salt of benzoic acid. Foods containing sodium benzoate include soda, salad dressings, condiments, fruit juices, wines, and snack foods.
Studies for using ascorbic acid and sodium benzoate in cosmetics are lacking, especially in skincare routines with multiple steps.
We always recommend speaking with a professional, such as a dermatologist, if you have any concerns.
Learn more about Sodium BenzoateTrisodium 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. Stay hydrated!
Learn more about WaterIngredient Ratings
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When to use
The Ordinary Multi-Peptide Serum for Hair Density 36 ingredients
Olaplex Nº.9 Bond Protector Nourishing Hair Serum 31 ingredients
Reviews
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