What it is
Isoceteth-20 is made by reacting branched isocetyl alcohol with about 20 units of ethylene oxide, producing a nonionic surfactant with both oil-loving and water-loving regions. This makes it useful for emulsifying oils into water and for solubilizing fragrances and other lipophilic ingredients into aqueous systems. In sunscreens it helps create stable, pleasant-feeling emulsions and is not a UV filter.
Safety & warnings
Ethoxylated surfactants like Isoceteth-20 are generally well tolerated in cosmetics. As with other PEG-type ingredients, purity matters because trace 1,4-dioxane can form during ethoxylation; reputable suppliers control for this. It is not a recognized common allergen at typical use levels.
Origin & sourcing
Synthetic ethoxylated fatty alcohol (isocetyl alcohol reacted with ethylene oxide).
Questions everyone asks
What is Isoceteth-20 for?
It is a nonionic surfactant used to emulsify oils into water and to solubilize fragrances and other oily ingredients in a formula.
Is the '20' meaningful?
Yes. The number indicates roughly the number of ethylene oxide units added, which influences how water-soluble and how effective an emulsifier it is.