Ingredient dictionary

Steareth-20

Also listed as: PEG-20 Stearyl Ether, Polyoxyethylene (20) stearyl ether

Steareth-20 is a gentle emulsifier, made from stearyl alcohol and ethylene oxide, that keeps oil and water blended together. It is on the label of 24 products in our library. Checked against our library November 6, 2026.

The catch: none for most people; check the full product list if your skin reacts easily.

What Steareth-20 does

Blends oil and water into stable mixtures
Helps waxes spread evenly in mascara
Adds a light, smooth feel
Helps conditioners rinse out cleanly

Steareth-20 starts with stearyl alcohol, a fatty alcohol usually derived from plant or animal fats. Chemists add ethylene oxide to it, which builds a chain of about 20 water-loving units onto the fatty end. That split personality, oil-loving on one side and water-loving on the other, is what makes it an emulsifier.

Formulators use it to hold creams, conditioners and deodorants together so they stay smooth and do not separate. In mascara, it can help waxes and water-based ingredients blend evenly. It usually feels light on skin and hair and rinses out easily, so it rarely leaves a heavy film.

Good for

Suits most people, since it is used in light creams, conditioners, deodorants and mascaras that need to stay evenly mixed.

Be careful if

Nothing in particular for most skin types.

Frequently asked questions

Is Steareth-20 safe?

Steareth-20 is generally well tolerated and is used widely in rinse-off and leave-on products. Like any emulsifier, it can irritate a small number of sensitive people, so patch testing a new product is a sensible habit. If you have a known reaction to similar ingredients, check with a dermatologist.

Does Steareth-20 make hair greasy?

Usually not. It is used in conditioners to help ingredients spread and rinse away, and in leave-in products it sits lightly. Its feel depends on the whole formula, so a heavy oil or wax in the same product will still be noticeable.