CYCLOTETRASILOXANE (octamethylcyclotetrasiloxane)
Official label name (INCIInternational name of cosmetic ingredients: the one printed on the pack. name, EU glossary of cosmetic ingredient names), No 7886
- Prohibited in cosmetics (Annex II)
CYCLOTETRASILOXANE (octamethylcyclotetrasiloxane): Prohibited in cosmetics (Annex II, entry 1388), under Regulation (EC) No 1223/2009. Good to know: classified toxic for reproduction (category 2); hazardous to the aquatic environment. The REACH Regulation restricts it in cosmetics (see “Other EU rules”). Annexes of the Regulation consulted on 23 October 2026.
Who it concerns
This ingredient is prohibited in cosmetics in the European Union: what follows describes its hazards, not a permitted use.
What official classifications and rules say for each group. A classification describes the hazard of the pure substance, not the risk of a product that contains it, which depends on the dose and the exposure.
Prohibition or serious classificationThe text prohibits the substance for this use, or ranks it among the most serious hazards (known or presumed carcinogenic, mutagenic or reprotoxic, identified endocrine disruptor).Worth watchingThe text sets a condition or flags a hazard worth knowing: allergen, suspected effect, condition for children, hazard to the aquatic environment.For informationOfficial information with no condition on a finished product: warning to read, irritation of the pure substance.
Pregnancy and breastfeeding
Worth watchingThe text sets a condition or flags a hazard worth knowing: allergen, suspected effect, condition for children, hazard to the aquatic environment.
Worth watching Classified under the CLPEU regulation that classifies chemicals by their hazards (EC No 1272/2008). Regulation: reproductive toxicity, category 2 (Repr. 2), a hazard to fertility.
For a question about your own situation, ask your doctor, midwife or pharmacist.
Babies and children
Prohibited in cosmetics in the European Union for everyone, whatever the age or situation: no specific condition is therefore needed for this group.
Skin, eyes and allergies
No harmonised classification for sensitisation, irritation or eye damage, and no obligation to label it as an allergen.
Environment
Prohibition or serious classificationThe text prohibits the substance for this use, or ranks it among the most serious hazards (known or presumed carcinogenic, mutagenic or reprotoxic, identified endocrine disruptor).
Worth watching Classified under the CLP Regulation: hazardous to the aquatic environment, long term, category 1 (Aquatic Chronic 1).
Prohibition or serious classification ECHAEuropean Chemicals Agency. has included it in the Candidate List (substances of very high concern, REACH Regulation) because it is persistent, bioaccumulative and toxic (PBT) and very persistent and very bioaccumulative (vPvB).
Read on the label
The Cosmetics Regulation requires no warning to be printed for this ingredient.
Regulation (EC) No 1272/2008 (CLP), consolidated version, Annex VI table 3, retrieved 21 October 2026.
ECHA, Candidate List of substances of very high concern for authorisation (REACH), retrieved 23 October 2026, source updated 23 October 2026.
Source: European Chemicals Agency (ECHA), Candidate List.
Other EU rules
These rules are not in the Cosmetics Regulation; each one says which products it applies to.
The REACH Regulation prohibits placing on the market a wash-off cosmetic containing 0.1% or more of D4 (cyclotetrasiloxane) since 31 January 2020, and any other cosmetic containing as much after 6 June 2027.
In plain words
What it is used for
Functions declared by manufacturers:
Emollient (skin conditioning): softens and smooths the skin.
Hair conditioning: leaves the hair easy to comb, supple, soft and shiny and/or imparts volume, lightness, gloss, etc.
Solvent: dissolves other substances.
Functions declared in the CosIngThe European Commission's database of cosmetic ingredients. inventory. CosIng, inventory of cosmetic ingredients (INCI names, CAS, EC, functions), retrieved 21 October 2026.
Definitions of functions (decision repealed on 8 May 2020, cited for information). Decision 2006/257/EC, inventory of cosmetic ingredients (definitions of functions), retrieved 22 October 2026.
What the rules say
It is prohibited to use it in a cosmetic product sold in the European Union, whatever the dose. If it appears on the ingredient list of a recent product, this needs checking: the record may be old or wrong, or the product intended for another market.
CosIng, Annex II of Regulation (EC) No 1223/2009 (prohibited substances), retrieved 23 October 2026, source updated 13 October 2026.
Hazard and risk
The CLP Regulation classifies this substance as toxic for reproduction, category 2 (suspected effect, without enough evidence for a higher category).
This classification describes what the substance can cause (a hazard), not what happens when using a product (a risk): the risk depends on the dose, the form and the route of exposure (skin, inhalation, ingestion).
Already prohibited in cosmetics (Annex II).
Regulation (EC) No 1272/2008 (CLP), consolidated version, Annex VI table 3, retrieved 21 October 2026.
The text of the annexes
Prohibited in cosmetics
CosIng links the name CYCLOTETRASILOXANE to this Annex II entry.
- Entry
- Annex II, No 1388
- Substance
- Octamethylcyclotetrasiloxane; D4
- CAS
- 556-67-2
- EC
- 209-136-7
Dates in the act (1)
- Entry into force on 12 June 2019
Excerpts from the English text published in the Official Journal. A date may concern only some substances of the act: the excerpt says so.
Regulation (EC) No 1223/2009, Annex II, entry 1388. CosIng, Annex II of Regulation (EC) No 1223/2009 (prohibited substances), retrieved 23 October 2026, source updated 13 October 2026.
Entry from Regulation (EU) 2019/831, adopted on 22 May 2019.
SCCSEU Scientific Committee on Consumer Safety: it assesses cosmetic ingredients. opinions cited: Opinion on Octamethylcyclotetrasiloxane (D4); Opinion on Cyclomethicone: D4 and D5.
What has changed, and what will change
Dates of the texts that cover this ingredient. A text date may cover several substances: the details of each entry are below.
Annex II, entry 1388: introduced or replaced by Regulation (EU) 2019/831
Annex II, entry 1388: applies from this date
CLP classification “Repr. 2” applicable at the latest from this date (Regulation (EU) 2020/1182)
Identity
- CosIng identifier
- 33104
- CAS (according to CosIng)
- 293-51-6, 556-67-2
- EC (according to CosIng)
- 209-136-7
- Declared functions
- Skin conditioning: emollient, Hair conditioning, Solvent
- Wikidata
- Q2013804
- ECHA InfoCard
- 100.008.307
CosIng cites 2 CAS numbers for this name: it covers several substances.
CosIng inventory. CosIng, inventory of cosmetic ingredients (INCI names, CAS, EC, functions), retrieved 21 October 2026.
Wikidata, items with a CosIng identifier (P3073), retrieved 22 October 2026.
Wikidata, PubChem and ECHA links are published only when verified: same CosIng identifier, a single item, matching CAS number.
Classified hazard (CLP Regulation)
The harmonised classification is the one set by the European Union for the whole Union. H codes refer to the hazard statements of Annex III of Regulation (EC) No 1272/2008.
octamethylcyclotetrasiloxane; [D4]
Reproductive toxicity, category 2 (Repr. 2)
- Hazard classes
- Reproductive toxicity, category 2 (Repr. 2)
Hazardous to the aquatic environment, long term, category 1 (Aquatic Chronic 1) - Hazard statements
- H361f *** H410
Annex VI, entry 014-018-00-1, linked by CAS 556-67-2. Regulation (EC) No 1272/2008 (CLP), consolidated version, Annex VI table 3, retrieved 21 October 2026.
Entry introduced or replaced by Regulation (EU) 2020/1182, applicable at the latest from 1 March 2022.
Elsewhere in the world
Information on other jurisdictions, with no effect on sale in France. What is covered, and what is not yet.
Comparison between countries
Most restrictive status in each country, and the maximum concentration cited. The details and the source of each rule follow.
| Country | Rule | Maximum concentration cited |
|---|---|---|
| European Union | Prohibited in cosmetics | not cited |
| United Kingdom | Prohibited in cosmetics | not cited |
| Switzerland | EU Regulation applies | not cited |
| United States (federal) | No federal rule recorded | not cited |
| Japan | No entry in the lists recorded | not cited |
| South Korea | Restricted differs from the EU | 8.7% |
| China | Not on the prohibited lists recorded (lists of allowed substances are not recorded) | not cited |
| Australia | No entry in the lists recorded | not cited |
| Brazil | No entry in the lists recorded | not cited |
United Kingdom (Great Britain)
- Prohibited in cosmetics (Annex II)
Same entries as in the European Union. Their maximum concentrations are compared in the “Comparison between countries” table; other conditions (product types, warnings) may differ.
Annexes II to VI in force. United Kingdom, Annexes II to VI of Regulation (EC) No 1223/2009 as retained and amended, retrieved 21 October 2026.
Contains public sector information licensed under the Open Government Licence v3.0.
Northern Ireland applies EU law.
Switzerland
Regulation (EC) No 1223/2009 applies in Switzerland (Article 54 of the Ordinance on Foodstuffs and Utility Articles).
Switzerland, FDHA Ordinance on Cosmetic Products (OCos, SR 817.023.31), consolidated version, retrieved 22 October 2026.
United States, federal rules
None of the integrated sections of the federal code (21 CFR 700.11 to 700.27 and 250.250) targets this name. The FDA does not publish a list of allowed ingredients.
United States, 21 CFR part 700 and section 250.250 (FDA rules on cosmetic ingredients), eCFR, retrieved 21 October 2026.
The eCFR is not an official legal edition of the Code of Federal Regulations.
South Korea
- Restricted: 사이클로테트라실록세인 (CYCLOTETRASILOXANE)
별표 2, 기타 (other substances with limits), entry 36, page 33. Limit: 8.7%.
South Korea, MFDS Regulation on Safety Standards for Cosmetics, Notification 2026-19, retrieved 22 October 2026.
Source: 식품의약품안전처 (MFDS), 화장품 안전기준 등에 관한 규정, via law.go.kr; table formatted by the publisher of this site.
Recorded cosmetics that contain it
13 recorded products list it, according to Open Beauty Facts contributors. Records are dated: the formula may have changed. See the list (in French).
Open Beauty Facts, export of cosmetic products, retrieved 23 October 2026.
Data “Open Beauty Facts and its contributors”, licensed under ODbL 1.0 (opendatacommons.org/licenses/odbl/1-0); derived table distributed under the same licence.
Glossary: Commission Implementing Decision (EU) 2025/1175. Page updated on 23 October 2026.