Ingredient dictionary

Steareth-21

Also listed as: Polyoxyethylene (21) Stearyl Ether

Steareth-21 is an emulsifier made from a fatty alcohol that keeps oil and water blended together in a formula. It is on the label of 16 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-21 does

Helps oil and water mix smoothly
Keeps creams and sticks stable
Helps other ingredients blend evenly

Steareth-21 is made by reacting stearyl alcohol, a fatty alcohol usually derived from plant or animal fats, with ethylene oxide. That reaction attaches a chain of 21 ethylene oxide units to each molecule. The result has one end that likes water and one end that likes oil, which is what lets it work as an emulsifier.

Formulators use it because it helps oil and water blend and stay together, which keeps a product smooth and even. In deodorants, it is often used alongside other ingredients to keep the formula uniform from first use to last. It is generally well tolerated and shows up in many creams, lotions and sticks.

Good for

Suits formulas that need a smooth, stable, evenly blended texture, such as many deodorants and creams.

Be careful if

Nothing in particular for most skin types.

Frequently asked questions

Is Steareth-21 safe to use?

Steareth-21 is widely used in cosmetics and is generally well tolerated. As with any ingredient, a person with very sensitive skin may still react, so a patch test on a small area is a sensible first step with a new product.

What does Steareth-21 do in deodorant?

In deodorant, it mainly acts as an emulsifier. It helps the oily and watery parts of the formula stay blended, so the product spreads evenly and stays uniform. It does not itself stop sweat or odor; other ingredients handle those jobs.