Behentrimonium Methosulfate
A gentle conditioning agent from rapeseed oil that gives conditioners their slip and detangling power. Despite the name, it is not a sulfate.
Curly Girl note: Not a sulfate — 'methosulfate' is only the counter-ion of a gentle conditioning agent.
About Behentrimonium Methosulfate
Behentrimonium methosulfate is a quaternary ammonium compound, or 'quat', made from behenyl alcohol — a long, 22-carbon fatty alcohol usually sourced from rapeseed (canola). It carries a permanent positive charge, which draws it to hair; hair surfaces, especially damaged ones, carry a negative charge.
In conditioners, leave-ins and detangling creams it is one of the most effective ingredients for slip. It forms a thin, smooth layer on each strand that cuts friction, reduces static and frizz and lets a comb or fingers glide through knots. Formulators like it because it is milder than many other quats and works well with fatty alcohols to build thick, creamy textures; the raw material sold as 'BTMS' is a blend of behentrimonium methosulfate and cetearyl alcohol.
The word 'methosulfate' alarms people following the Curly Girl Method, but it has nothing to do with sulfate cleansers. It's simply the negatively charged partner that balances the quat's positive charge. Behentrimonium methosulfate does not clean, foam or strip hair, and it is approved for the Curly Girl Method.
Who tends to love it: almost everyone with curly, coily, relaxed or tangle-prone hair. People with very fine, low porosity hair sometimes find rich conditioners based on it a little heavy if used as a leave-in, and should use smaller amounts. It is considered gentle on skin compared with shorter-chain quats.
How our checker rates it
| Mode | Rating | Why |
|---|---|---|
| Curly Girl | OK | No concerns for this mode. |
| Relaxed hair | Good | Conditioning agent — adds slip and helps protect damaged areas. |
| Low porosity | OK | No concerns for this mode. |
| Protein-sensitive | OK | No concerns for this mode. |
Ratings assume it is listed near the top of the label. After the first preservative or fragrance (likely 1% or less) most cautions soften.
What conditioner ingredients do
Positively charged (cationic) ingredients — quats and polyquats — that cling to damaged areas of the hair for slip, detangling and less static.
Also listed as
- btms
- behentrimonium methosulphate
Similar ingredients
Sources
Last data update:
- Robbins CR. Chemical and Physical Behavior of Human Hair. 5th ed. Springer; 2012. Reference text on hair structure, surfactants, conditioning agents, protein, heat and chemical treatments.
- Massey L, Chiu M. Curly Girl: The Handbook. Workman Publishing; 2011. Origin of the Curly Girl Method rules (no sulfates, no non-soluble silicones, no drying alcohols).
- Cosmetic Ingredient Review (CIR). Ingredient safety assessments. Safety assessments for cosmetic ingredients cited on ingredient pages.
How we research and update pages: editorial policy. Spotted an error? Tell us.