Ingredient dictionary

Trideceth-9

Trideceth-9 is a gentle nonionic surfactant that helps oil and water mix and lifts dirt and oil off the skin. It is on the label of 4 products in our library. Checked against our library November 6, 2026.

What Trideceth-9 does

Helps oil and water blend into one mix
Lifts oil and dirt during cleansing
Helps keep formulas smooth and stable

Trideceth-9 is made by attaching a chain of ethylene oxide units to tridecyl alcohol, a fatty alcohol. The '9' in its name refers to the average length of that chain. The result has one end that likes water and one end that likes oil, which is why it acts as a surfactant.

Formulators use it in cleansers and moisturizers to blend oil and water, so creams stay uniform and resist separating. In cleansers it helps lift oil and makeup off the skin. It tends to rinse clean and leave little residue.

Good for

Suits cleansers and moisturizers, where a smooth, easy-rinsing texture is the goal.

Frequently asked questions

Is Trideceth-9 harsh on skin?

Most people tolerate it well at the levels used in cosmetics. Like any cleansing agent, it can feel drying on very sensitive skin, so patch testing a new product first is a sensible habit.

What does Trideceth-9 do in a cleanser?

It acts as a surfactant, so it surrounds oil and dirt and lets water wash them away. It also helps the cleanser spread evenly and rinse clean, and it keeps oily ingredients mixed into the water-based formula.