Skin science article
K18 Hair Leave-In Molecular Repair Hair Mask Versus The INKEY List PCA Bond Repair Hair Treatment
K18 Hair Leave-In Molecular Repair Hair Mask Versus The INKEY List PCA Bond Repair Hair Treatment What's inside Key Ingredients No key ingredients Benefits Concerns Ingredients Side-by-side Water Alcohol Denat. Propylene Glycol Cetearyl Alcohol Dicaprylyl Ethe
K18 Hair Leave-In Molecular Repair Hair Mask Versus The INKEY List PCA Bond Repair Hair Treatment
What's inside
Key Ingredients
No key ingredients
Benefits
Concerns
Ingredients Side-by-side
Water
Alcohol Denat.
Propylene Glycol
Cetearyl Alcohol
Dicaprylyl Ether
Cetyl Esters
Behentrimonium Chloride
Polysorbate 20
Sh-Oligopeptide-78
Hydrolyzed Wheat Protein
Hydrolyzed Wheat Starch
Isopropyl Alcohol
Tocopherol
Phenoxyethanol
Potassium Sorbate
Citric Acid
Parfum
Geraniol
Linalool
Hexyl Cinnamal
Benzyl Alcohol
Water, Alcohol Denat., Propylene Glycol, Cetearyl Alcohol, Dicaprylyl Ether, Cetyl Esters, Behentrimonium Chloride, Polysorbate 20, Sh-Oligopeptide-78, Hydrolyzed Wheat Protein, Hydrolyzed Wheat Starch, Isopropyl Alcohol, Tocopherol, Phenoxyethanol, Potassium Sorbate, Citric Acid, Parfum, Geraniol, Linalool, Hexyl Cinnamal, Benzyl Alcohol
Amodimethicone
Butylene Glycol
Betaine
Bis-PCA Dimethicone
Sorbitan Laurate
Cetrimonium Chloride
Panthenol
Trideceth-12
Glycerin
PEG-40 Hydrogenated Castor Oil
Sodium Benzoate
Hydrolyzed Pea Protein Pg-Propyl Silanetriol
Aminomethyl Propanol
Aloe Barbadensis Leaf Juice Powder
Disodium PEG-12 Dimethicone Sulfosuccinate
Polyglyceryl-4 Laurate
Alcohol
Helianthus Annuus Seed Extract
Dilauryl Citrate
Avena Strigosa Seed Extract
Lecithin
Water, Amodimethicone, Butylene Glycol, Betaine, Bis-PCA Dimethicone, Sorbitan Laurate, Cetrimonium Chloride, Panthenol, Trideceth-12, Glycerin, PEG-40 Hydrogenated Castor Oil, Sodium Benzoate, Hydrolyzed Pea Protein Pg-Propyl Silanetriol, Aminomethyl Propanol, Aloe Barbadensis Leaf Juice Powder, Disodium PEG-12 Dimethicone Sulfosuccinate, Potassium Sorbate, Citric Acid, Polyglyceryl-4 Laurate, Alcohol, Helianthus Annuus Seed Extract, Dilauryl Citrate, Phenoxyethanol, Avena Strigosa Seed Extract, Lecithin
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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.
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.
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.
Potassium Sorbate is a preservative used to prevent yeast and mold in products. It is commonly found in both cosmetic and food products.
This ingredient comes from potassium salt derived from sorbic acid. Sorbic acid is a natural antibiotic and effective against fungus.
Both potassium sorbate and sorbic acid can be found in baked goods, cheeses, dried meats, dried fruit, ice cream, pickles, wine, yogurt, and more.
You'll often find this ingredient used with other preservatives.
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!