Cyclotetrasiloxane
Avoid
Official INCI name
D4, a volatile silicone. Classed in the EU as possibly harmful to fertility and as persisting in the environment, so it's restricted in wash-off products since 2020 and in leave-on products from 2026.
What it does
Emollient. Oils, butters, esters and silicones that soften and smooth.
Worth knowing
Under review or restricted for possible effects on the hormone (endocrine) system.
Persists in the environment or harms aquatic life (e.g. microplastics, some UV filters).
Also written as
Scans recognise it under every one of these names.
D4
“Cyclotetrasiloxane” is its name in the EU glossary of common ingredient names (no. 7886), the names labels in the EU must use. © European Union, EUR-Lex.