Encyclopedia · conditioning agent
Cetyl alcohol
A 16-carbon fatty alcohol that thickens conditioners and pairs with conditioning surfactants to form the gel; it is not a drying alcohol.
What it is
A waxy solid used in rinse-off and leave-in products as a thickener, emollient and co-emulsifier. It is named among the fatty components of creme rinses. Gavazzoni Dias 2015
How it works
It forms layered gels with cationic surfactants. In a lab study, cetrimonium-based gels were weaker than behentrimonium-based ones, and that gel structure influenced wet combing. Davies 2020
What the studies show
- Formulation structure only. No human hair trial was found.
Side effects and safety
Contact allergy is rare. In a 2022 case series, two of three patients allergic to stearyl alcohol also reacted to cetyl alcohol. Nishioka 2022
Bottom line
Safe and useful. Ignore claims that it dries hair. If you react to creams containing cetyl, stearyl or cetearyl alcohol, check your conditioners too. We are moderately sure of this.
Studies 3
Gavazzoni Dias MF. Hair cosmetics: an overview. Int J Trichology. 2015
Result: Wetting breaks hydrogen bonds, so blow-dry and flat-iron shapes are temporary, while chemical straightening and perming reshape hair by breaking and reforming disulfide bonds.
Read the study ↗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.
- 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.
- Behenyl alcoholThe longest common conditioner fatty alcohol, a stiff wax that gives rich, thick conditioners; it has no hair-specific studies.
- Cetrimonium chlorideA shorter-chain conditioning ingredient, a bit less effective than the behentrimonium salts but lighter, found in many shampoos, light conditioners and sprays.