Encyclopedia · conditioning agent
Cetearyl alcohol
A 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.
What it is
A fatty alcohol mixture of 16- and 18-carbon chains, solid at room temperature. A review of hair cosmetics lists cetyl, stearyl and cetostearyl alcohols as the fatty components of creme rinses. Gavazzoni Dias 2015
How it works
With a cationic surfactant and water it forms a layered gel. In a formulation-lab study, the ratio of cationic surfactant to fatty alcohol set the gel's structural strength, and this affected wet combing. Davies 2020 Competition among cationics, fatty alcohols and silicone for the hair surface has been studied by Procter & Gamble collaborators. Labarre 2023 On its own a fatty alcohol adds slip and softness, but its separate effect on combing was not isolated in the abstracts we opened.
What the studies show
- No standalone human trial was found. The evidence is formulation-structure work.
Side effects and safety
The Cosmetic Ingredient Review assessment of the related stearyl alcohol found low acute toxicity and minimal irritation, concluding it was safe as currently used in cosmetics. CIR 1985 Allergic contact dermatitis to fatty alcohols is rare but documented: seven patients reacted to stearyl alcohol in topical medicines, and 2 of 3 tested were also positive to cetyl alcohol. Nishioka 2022
Bottom line
Safe, cheap and desirable in conditioners. Avoid it only if you have a diagnosed fatty-alcohol allergy. We are confident about safety and moderately sure about its exact function.
Fun facts
"Alcohol" on the label does not mean drying. Fatty alcohols are waxes, the opposite of the volatile ethanol in hair sprays (see alcohol denat.).
Studies 5
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 ↗Labarre L et al. Hair surface interactions against different chemical functional groups as a function of environment and hair condition. Int J Cosmet Sci. 2023
Result: Hydrophobic interaction drove deposition on virgin hair and electrostatic interaction on bleached hair.
Read the study ↗Cosmetic Ingredient Review. Final report on the safety assessment of stearyl alcohol, oleyl alcohol, and octyl dodecanol. J Am Coll Toxicol. 1985
Result: Very low acute oral toxicity, minimal eye and skin irritation, no sensitisation or phototoxicity; concluded safe as currently used in cosmetics.
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
- Cetyl alcoholA 16-carbon fatty alcohol that thickens conditioners and pairs with conditioning surfactants to form the gel; 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.
- 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.
- 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.
- How conditioner worksRinse-off conditioner coats hair with a positively charged layer that cuts friction and tangling; it does not repair structural damage.