Encyclopedia · conditioning agent
Behenyl alcohol
The longest common conditioner fatty alcohol, a stiff wax that gives rich, thick conditioners; it has no hair-specific studies.
What it is
A waxy alcohol with 22 carbons. The same compound, docosanol, is an over-the-counter cold sore cream in some countries, which is a different use unrelated to hair.
How it works
Long-chain fatty alcohols build stiffer gels with behentrimonium salts, which produced the highest structural strength in lab work. Davies 2020 That study used an unspecified fatty alcohol, so behenyl-specific data are lacking. We found no hair study on behenyl alcohol alone, so any hair-specific claim is grade E.
Side effects and safety
Related fatty alcohols are low risk, with rare contact allergy. Nishioka 2022
Bottom line
A neutral, safe thickener. We are unsure about its function in hair and fairly sure about its safety, by analogy with related fatty alcohols.
Studies 2
Davies AR, Amin S. Microstructure design of CTAC:FA and BTAC:FA lamellar gels using an automated formulation platform. Int J Cosmet Sci. 2020
Result: Gel structure strength was highest for behentrimonium systems, peaking at a surfactant to fatty alcohol ratio of 6:10, and it affected wet combing.
Read the study ↗Nishioka K et al. Seven cases of contact dermatitis due to stearyl alcohol. 2022
Result: All seven were patch-test positive to stearyl alcohol, and two of three tested also reacted to cetyl alcohol.
Read the study ↗Related
- Cetearyl alcoholA waxy blend of cetyl and stearyl alcohols that thickens conditioners and builds the gel that carries the conditioning agent; despite the name, it is not a drying alcohol.
- Behentrimonium chlorideA long-chain, positively charged conditioning ingredient that clings to hair and detangles it, with good lab evidence for smoothing and none for repair.
- Stearyl alcoholAn 18-carbon fatty alcohol, a slightly heavier cousin of cetyl alcohol, used to thicken and soften conditioners; safe at cosmetic levels and rarely allergenic.