Encyclopedia
Every molecule that touches your hair
From proven medicines to kitchen-cupboard oils, with the studies behind each one.
16 entries
A
-
surfactant
Ammonium laureth sulfate
The ammonium-salt version of SLES, an ethoxylated sulfate cleanser that is gentler than lauryl sulfates and can carry a trace by-product called 1,4-dioxane.
-
surfactant
Ammonium lauryl sulfate
The ammonium-salt twin of SLS, a strong cleanser with essentially the same cleaning power and irritation profile.
B
-
other
Bentonite
A swelling clay used in clay masks and some matte styling products as an absorbent and thickener; "bentonite washes" are untested for hair.
C
-
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.
D
-
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
-
conditioning agent
Guar hydroxypropyltrimonium chloride
A plant-derived cationic polymer used in conditioning shampoos and "natural" conditioners to ease wet combing; it can build up on hair.
P
-
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.
S
-
anti dandruff
Salicylic acid
A scale-loosening ingredient that helps thick flakes and scalp psoriasis plaques and works best paired with an antifungal.
-
surfactant
Sodium C14-16 olefin sulfonate
A sulfonate-based cleanser common in sulfate-free shampoos that is still a strong degreaser, so sulfate-free does not always mean gentle.
-
surfactant
Sodium laureth sulfate
The workhorse cleanser of mainstream shampoos, SLS with a short ethylene-oxide chain added, which keeps most of the cleaning and foam and is gentler, with a trace by-product called 1,4-dioxane.
-
surfactant
Sodium lauroyl sarcosinate
An amino-acid-derived cleanser with good foam and cleaning power that is marketed as mild, though its mildness sits in the middle.
-
surfactant
Sodium lauryl sulfate
A cheap, strong cleanser and foamer that removes oil very well but is the most irritating common shampoo surfactant, so dermatologists use it as their standard test irritant.
-
chelator
Sodium phytate
A rice- or corn-derived chelator used in natural shampoos as a preservative booster and iron and copper binder, with no hair trials.
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.
-
chelator
Tetrasodium glutamate diacetate
A biodegradable, glutamic-acid-based chelator marketed as a greener EDTA replacement, with essentially no hair-specific data.
Z
-
anti dandruff
Zinc pyrithione
The most widely used anti-dandruff shampoo ingredient, proven in large trials to cut flaking, though most of those trials were run by the companies that sell it.