Encyclopedia
Every molecule that touches your hair
From proven medicines to kitchen-cupboard oils, with the studies behind each one.
34 entries
1
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other
18-MEA (18-methyleicosanoic acid)
The fatty acid on the outer surface of virgin hair that makes it water-repellent and smooth, lost with weathering and chemical treatment.
A
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other
Alcohol denat.
Ordinary ethanol made undrinkable, a fast-drying solvent in hair sprays and gels that is not the same as the fatty alcohols in conditioners.
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silicone
Amodimethicone
A dimethicone with positively charged amine groups, so it clings to damaged hair and resists rinsing better than plain dimethicone.
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oil or butter
Argan oil
A popular finishing oil for shine and anti-frizz, with only small lab studies behind it and no significant evidence for hair quality or growth.
-
oil or butter
Avocado oil
A rich oleic-acid oil common in deep conditioners, with no hair-fibre or clinical hair studies found.
B
-
oil or butter
Batana oil
Batana oil is a trending Honduran palm-nut oil sold for hair growth, with no peer-reviewed hair study found.
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conditioning agent
Behentrimonium chloride
A long-chain, positively charged conditioning ingredient that clings to hair and detangles it, with good lab evidence for smoothing and none for repair.
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silicone
Bis-aminopropyl dimethicone
An amino-terminated silicone related to amodimethicone, used in conditioners and colour-care products to stick to damaged hair.
C
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oil or butter
Castor oil
Castor oil is a thick sealant that suits dry hair, but no controlled human trial shows it grows hair, and in rare cases it has matted a whole head of hair irreversibly.
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other
Ceramides
Waxy lipids from the cement between hair cells; a lab study with ceramide-containing liposomes restored some lipids and break resistance, but retail products lack hair trials.
-
chelator
Citric acid
The most common pH adjuster in shampoos and conditioners and, in a 2025 lab study, a calcium-removing treatment that strengthened chemically treated hair.
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oil or butter
Coconut oil
The best-studied hair oil; in lab work it cut protein loss and fatigue damage when used before washing, but almost all studies come from coconut-oil sellers.
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protein or peptide
Collagen peptides
A protein powder with modest skin evidence and very little for hair.
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silicone
Cyclopentasiloxane
A volatile silicone that spreads easily and evaporates, used to carry heavier silicones in serums; now restricted in the EU for environmental reasons.
D
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silicone
Dimethicone
The standard hair silicone, a water-insoluble oil that coats the fibre for slip, shine and friction control without repairing anything.
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silicone
Dimethiconol
A dimethicone with hydroxyl end groups, usually supplied as a thick gum emulsion for longer-lasting slip in rinse-off conditioners.
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chelator
Disodium EDTA
The classic cosmetic chelator, which grabs calcium, magnesium, iron and copper so shampoos lather and keep in hard water, with no clinical hair trials of its own.
G
-
humectant
Glycerin
A cheap water-binding ingredient in nearly every conditioner; no peer-reviewed hair study tests it, and the popular humidity rules are untested.
H
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humectant
Honey
A sugar-rich natural humectant used in DIY and commercial masks; no hair-fibre study was found.
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humectant
Hyaluronic acid
A large water-binding sugar molecule added to some leave-ins and masks; no hair-fibre study was found.
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protein or peptide
Hydrolyzed keratin
Keratin fragments, usually from wool or feathers, that coat damaged hair and in lab tests partly entered it and raised wet strength; the evidence is small and industry-linked.
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protein or peptide
Hydrolyzed rice protein
A plant, gluten-free protein used in conditioners and volumizers; we found no hair study for it.
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protein or peptide
Hydrolyzed silk
Silk-derived peptides added for gloss and softness; the cosmetic safety panel judged most silk proteins safe, but there is no hair efficacy study.
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protein or peptide
Hydrolyzed wheat protein
A common conditioner protein that raised dry strength of bleached and heat-damaged tresses in one lab test, with a small but real allergy risk.
J
-
oil or butter
Jojoba oil
A liquid wax often said to mimic scalp sebum; we found no hair-specific efficacy study.
M
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oil or butter
Mineral oil
A cheap, non-penetrating hydrocarbon oil that coats hair for shine and slip but, unlike coconut oil, did not protect against protein loss in lab tests.
O
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oil or butter
Olive oil
A traditional hair oil whose only supporting hair data is that its film thinned on hair like coconut oil did, suggesting some absorption.
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protein or peptide
Oral keratin supplements
Keratin capsules with one small company-linked trial and no sign that swallowed keratin reaches your hair.
P
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colorant
p-Phenylenediamine (PPD)
The main dark permanent dye ingredient and one of the commonest hair-dye allergens; it colours well but can cause severe contact dermatitis in sensitised people.
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humectant
Panthenol
A small vitamin B5 alcohol that enters the hair cortex and raised break stress in a lab study; the only humectant here with real hair-fibre data.
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silicone
PEG-12 dimethicone
A dimethicone with polyethylene glycol side chains that makes it water-dispersible, so it rinses out more easily than classic silicones.
R
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other
Rice water
Rice water is the starchy water left after soaking or boiling rice, a free and harmless rinse with no clinical hair study behind its growth claims.
S
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humectant
Sodium PCA
A salt of an amino-acid derivative found in skin's natural moisturising factor, used as a humectant; no hair study was found.
T
-
chelator
Tetrasodium EDTA
The more alkaline, more soluble EDTA salt, with the same chelating job as disodium EDTA and wide use in clarifying and chelating shampoos.