Encyclopedia · conditioning agent
Stearyl alcohol
An 18-carbon fatty alcohol, a slightly heavier cousin of cetyl alcohol, used to thicken and soften conditioners; safe at cosmetic levels and rarely allergenic.
What it is
A waxy fatty alcohol used from under 0.1% to over 50% across cosmetics. The Cosmetic Ingredient Review report of 1985 on stearyl alcohol, oleyl alcohol and octyldodecanol found very low acute oral toxicity, minimal eye and skin irritation, no sensitisation in tests and no phototoxicity. It concluded they are safe as currently used in cosmetics. CIR 1985
How it works
It builds a layered gel with cationic surfactants and adds softness. Chain length alters gel structure (see cetyl alcohol and cetearyl alcohol). We found no stearyl-specific hair performance study.
What the studies show
- Safety review: low toxicity and irritation. CIR 1985
- Seven patients in Japan had allergic contact dermatitis from stearyl alcohol in topical medicines. All were patch-test positive, and cetyl alcohol was positive in two of three tested. This is rare. Nishioka 2022
Bottom line
A standard, safe conditioner ingredient. We are confident about its safety.
Studies 2
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
- 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.
- Cetyl alcoholA 16-carbon fatty alcohol that thickens conditioners and pairs with conditioning surfactants to form the gel; it is not a drying alcohol.
- Behenyl alcoholThe longest common conditioner fatty alcohol, a stiff wax that gives rich, thick conditioners; it has no hair-specific studies.
- How conditioner worksRinse-off conditioner coats hair with a positively charged layer that cuts friction and tangling; it does not repair structural damage.