Emulsifiers in cosmetics: what cetearyl alcohol, glyceryl stearate, polysorbates and PEGs do
Creams and lotions are mixtures of oil and water that would separate without help. How emulsifiers work, how to recognise the most common ones on an INCI list and what the numbers in names like PEG-100 Stearate or Polysorbate 20 mean.
Updated: 31 October 2026 · Reviewed by: Kamil Pyziak
Why creams need emulsifiers
Oil and water do not mix. Shake them together and they separate again within minutes. Yet most creams, lotions and many cleansers contain both: water for lightness and water-soluble ingredients, oils for softness and oil-soluble ingredients. An emulsifier is a molecule with a water-loving (hydrophilic) part and an oil-loving (lipophilic) part. It sits at the boundary between tiny droplets and the surrounding liquid and keeps the mixture stable.
There are two basic types of emulsion. In an oil-in-water emulsion, oil droplets are dispersed in water; most lotions and light creams are built this way and feel fresh. In a water-in-oil emulsion, water droplets are dispersed in oil; these feel richer and are used for example in some barrier creams, cold creams and water-resistant products. The choice of emulsifier largely decides which type you get.
Cetearyl alcohol and glyceryl stearate: the backbone of many creams
Cetearyl Alcohol is a mixture of two fatty alcohols, cetyl and stearyl alcohol. Despite the word “alcohol”, it is a waxy solid, not a drying solvent. On its own it is only a weak emulsifier; its main role is to thicken and stabilise emulsions and to give creams their soft, cushioned feel. It is often used together with a stronger emulsifier, for example as Cetearyl Alcohol with Ceteareth-20 or with Cetearyl Glucoside.
Glyceryl Stearate is an ester of glycerin and stearic acid. It is a mild, oil-leaning emulsifier and emollient that also helps with texture. Glyceryl Stearate SE (“self-emulsifying”) contains a small amount of soap, such as sodium or potassium stearate, which makes it work as an emulsifier on its own. A classic pairing is Glyceryl Stearate with PEG-100 Stearate.
Polysorbates and PEGs: what the numbers mean
Many emulsifiers are made by ethoxylation, a process that attaches chains of ethylene oxide units to a fatty molecule to make it more water-friendly. In names such as PEG-100 Stearate or Ceteareth-20, the number indicates the average number of ethylene oxide units: the higher it is, the more water-soluble the ingredient. PEG-40 Hydrogenated Castor Oil, for example, is a typical solubiliser that helps perfume or essential oils dissolve in watery toners.
Polysorbates are ethoxylated sorbitan esters. Here the number works differently: Polysorbate 20, 60 and 80 have a similar ethylene oxide chain, and the number indicates the fatty acid – lauric acid for 20, stearic acid for 60 and oleic acid for 80. Polysorbate 20 is common in toners, micellar waters and serums as a solubiliser, Polysorbate 60 and 80 in creams and lotions.
PEGs and 1,4-dioxane: what is behind the debate
Concerns about PEGs and other ethoxylated ingredients usually relate to 1,4-dioxane, a possible by-product of ethoxylation. In the EU, 1,4-dioxane itself is a prohibited substance in cosmetics, but the regulation allows technically unavoidable traces of prohibited substances provided the product remains safe. Raw material suppliers reduce such impurities by purification, and their levels are part of the quality control that the safety assessment relies on.
Ethoxylated ingredients are not accepted by many natural and organic certification standards, which is why products with such seals use other emulsifiers. That is a choice based on processing and certification rules, not proof that a PEG-containing product is unsafe.
Alternatives you will see in “natural” formulas
Without ethoxylation, formulators turn to emulsifiers based on sugars, olive oil, citric acid or lecithin. Common examples are Cetearyl Glucoside (often with Cetearyl Alcohol), Cetearyl Olivate with Sorbitan Olivate, Glyceryl Stearate Citrate, Sucrose Stearate and Lecithin. For water-in-oil emulsions, Polyglyceryl-3 Diisostearate and other polyglyceryl esters are common, and Potassium Cetyl Phosphate is widely used in sunscreens.
Some ingredients stabilise emulsions without being emulsifiers in the strict sense. Thickeners such as Carbomer or Xanthan Gum increase the viscosity of the water phase so droplets cannot easily move and merge. That is why many creams combine an emulsifier, a fatty alcohol and a thickener.
What the label does not tell you
The INCI list does not show which ingredients form a pre-made emulsifier blend, how much of each is used or whether the cream is oil-in-water or water-in-oil. Emulsifiers are usually present in a few percent and appear in the middle of the list, but their position says little about how gentle or effective the product is.
Emulsifiers are surfactants, and some people with very sensitive skin react to particular ones. If you suspect a reaction, compare the full ingredient lists of the products involved and ask a dermatologist; patch testing can help identify the actual culprit.