Silicones (Dimethicone & Cyclic Siloxanes): why to avoid them and what to use instead
Cyclic siloxanes (D4, D5, D6) are persistent and bioaccumulative in aquatic environments; the EU restricts them in rinse-off and, increasingly, leave-on products.
The short answer
Straight dimethicone is not a health hazard — the issue is environmental persistence for the cyclic forms and product build-up on hair. Prioritise removing cyclic siloxanes (anything ending in -siloxane or 'cyclomethicone'); linear dimethicone is a lower-priority swap.
- Where it hides
- Conditioners, serums, primers, sunscreens, hair-smoothing products
- Cleaner swap
- Plant oils and butters, behentrimonium methosulfate conditioners, or water-soluble silicones (PEG-modified) if slip is essential.
- Also listed as
- Dimethicone, Cyclopentasiloxane, D4, D5, Amodimethicone
The label names to scan for
- Cyclotetrasiloxane (D4)
- Cyclopentasiloxane (D5)
- Cyclohexasiloxane (D6)
- Cyclomethicone
- Dimethicone (build-up concern, not persistence)
What regulators have actually done
The EU restricts D4, D5 and D6 to 0.1% in wash-off cosmetics and has extended limits toward leave-on products; D4 is classified as a substance of very high concern under REACH.
Not all silicones are the same
Linear silicones like dimethicone are large, inert molecules that sit on the skin surface. Cyclic siloxanes — D4, D5, D6 — are small, volatile and the ones flagged as persistent, bioaccumulative and toxic to aquatic life. Reading the suffix is the fastest way to sort them: -siloxane and cyclomethicone are the ones regulators target.
The hair build-up question
Non-soluble silicones coat the hair shaft and need a sulphate or clarifying wash to remove. That's a cosmetic issue rather than a safety one, but it's why curly-hair routines exclude them. Water-soluble versions (prefixed PEG-) rinse out with ordinary shampoo.
Silicones (Dimethicone & Cyclic Siloxanes): frequently asked questions
Are silicones bad for your skin?+
No credible evidence says so. They are inert and non-comedogenic for most people. The stronger arguments against them are environmental persistence and hair build-up.
How do I spot the restricted ones?+
Look for names ending in -siloxane or the word cyclomethicone. Dimethicone and amodimethicone are the linear, lower-concern versions.