Steareth-20

Derivative of fatty alcohol stearyl alcohol

Functions as a surfactant and stabilizer

Helps keep ingredients together in an emulsion

Deemed safe as used in cosmetics

Steareth-20 is a derivative of the benign fatty ingredient stearyl alcohol. In cosmetics, it functions primarily as a surfactant but is also used to make products more stable, especially if they contain active ingredients in an emulsion.

Steareth ingredients may be animal-derived or synthetic. They are prepared by interacting with the chemical intermediate gas ethylene oxide with stearyl alcohol, a process which forms an entirely new stable compound. The number that comes after (for instance, 20) indicates the average number of ethylene oxide units used in the preparation.

There have been concerns about the safety of steareth ingredients because toxic 1,4-dioxane, a by-product of ethoxylation, can be produced; however, this is eliminated through purification processes. The independent Cosmetic Ingredient Review panel has ruled that steareth-20 is safe as used in cosmetics in amounts up to 25%.