Methyl Trimethicone
No meaningful concern for most people; irritation is possible but rare.
Also written as: Tetramethyl tetra(trimethylsiloxy)cyclotetrasiloxane blend
What it is
Methyl trimethicone is a low-viscosity branched silicone that evaporates from the skin after application, leaving a dry, powdery-smooth feel. Formulators use it as a lighter alternative to volatile cyclic silicones such as cyclopentasiloxane, since it is not one of the cyclic siloxanes restricted under REACH.
What it does well
Gives a light, dry finish and helps products spread
It thins heavy oils and pigments so a formula spreads easily, then evaporates so no oily film remains.
Moderate evidence
Where the EU stands
No specific restriction
Not restricted in EU cosmetics and not covered by the REACH Annex XVII entry 70 restriction on the cyclic siloxanes D4, D5 and D6.
