Ingredient file · Banned

Is cyclotetrasiloxane (D4) banned in cosmetics?

Q: What does EWG Skin Deep say about cyclotetrasiloxane (D4)?

EWG Skin Deep scores cyclotetrasiloxane (D4) 10 out of 10 with robust data, and lists use restrictions as high. Read 23 October 2026.

Yes, in the EU: Annex II lists cyclotetrasiloxane (D4) as a prohibited substance (entry 1388). California, the EU and FDA's named list, read 23 October 2026, with EWG Skin Deep's score.

SlipperSkin finding

Read on 23 October 2026, cyclotetrasiloxane (D4) is prohibited in the EU (Annex II) and will be banned in California from 2027; EWG Skin Deep scores it 10 out of 10.

From the California statute, the EU Cosmetics Regulation as consolidated on 1 May 2026, FDA’s page and EWG’s ingredient page, read 23 October 2026. We report what each says; we do not rate the ingredient.

Is cyclotetrasiloxane (D4) banned in cosmetics?

Yes, in the EU: Annex II lists cyclotetrasiloxane (D4) as a prohibited substance (entry 1388). California will ban it from 1 January 2027 (list (b)(4)). FDA's named list does not include it. EWG Skin Deep scores it 10 out of 10 (data: robust).

Cyclotetrasiloxane (D4): where it standsread 23 October 2026

Filled red marks a ban, blue a restriction, pale an ingredient that list does not name. FDA's page names 11 entries and none is cyclotetrasiloxane (D4). The EWG row marks its score; a bar shows a range.

What does the EU list say about cyclotetrasiloxane (D4)?

Annex II is the EU's list of prohibited substances. The entries for cyclotetrasiloxane (D4) are in the table below, as printed in the regulation consolidated on 1 May 2026.

Cyclotetrasiloxane (D4) in the EU Cosmetics Regulation, found by CAS number 556-67-2
Where	Annex	Cap, threshold and product type	Condition
Annex II, entry 1388 as printed: Octamethylcyclotetrasiloxane	Prohibited substances	prohibited all cosmetic products	No condition printed in the entry.

Is cyclotetrasiloxane (D4) on California's banned list?

It will be. California's Health and Safety Code section 108980 bans cyclotetrasiloxane (D4) from 1 January 2027 (list (b)(4)), when intentionally added.

What does EWG Skin Deep say about cyclotetrasiloxane (D4)?

EWG’s page gives cyclotetrasiloxane (D4) a hazard score of 10 out of 10 with robust data. Its concerns line reads, in part: Use restrictions (high), Endocrine disruption (moderate), Persistence and bioaccumulation (moderate), Non-reproductive organ system toxicity (moderate), and Ecotoxicology (low). The use-restrictions concern is high. The score is a hazard score on EWG's own scale; it is not a regulatory status.

Where is this read from?

More ingredient files: Diethylhexyl phthalate · Paraformaldehyde · Methylene glycol · all 66 ingredient files

Method: California's section 108980 and the EU's annexes were read in Chrome on 23 October 2026; EU lookups are by CAS number (556-67-2) across Annexes II, III, V and VI; EWG's page was kept only if its name matched exactly; the PubChem link is the compound the CAS number resolves to. Statutes change and EWG revises pages, nothing here is a safety verdict, and an ingredient that is not on a list is not endorsed.