Cosmetic ingredient

CYCLOPENTASILOXANE

CYCLOPENTASILOXANE is a cyclic dimethyl polysiloxane, a defined chemical structure specific to this ingredient. This characteristic helps explain why it appears in cosmetic products as a technical component of application and formulation.

2D molecular structure

CAS number

541-02-6

EC number

208-764-9

Molecular formula

C10H30O5Si5

Molecular weight

370.77

Chemical name

Decamethylcyclopentasiloxane

InChIKey

XMSXQFUHVRWGNA-UHFFFAOYSA-N

CYCLOPENTASILOXANE: what it is

CYCLOPENTASILOXANE: what it does in cosmetics

In a composition, CYCLOPENTASILOXANE may function as a skin-conditioning emollient, roles associated with conditioning the surface and its feel. It is also classified as a hair-conditioning agent and solvent, which explains its use across different types of products.

CYCLOPENTASILOXANE: conditions and care

In the European Union, it must not be placed on the market on its own, as a constituent of another substance, or in mixtures at a concentration of 0.1% by weight or higher after 6 June 2026. For rinse-off cosmetic products, the rule applies after 31 January 2020; for other cosmetics, after 6 June 2027.

Use limits

Restrictions and conditions of use

Cosmetic restriction

Restricted under COMMISSION REGULATION (EU) 2024/1328. 1. Shall not be placed on the market (a) as a substance on its own; (b) as a constituent of other substances; or (c) in mixtures; in a concentration equal to or greater than 0,1 % by weight of the respective substance after 6 June 2026. [...] 3. By way of derogation: (a) for D4 and D5 in wash-off cosmetic products, paragraph 1, point (c), shall apply after 31 January 2020. For the purposes of this point, “wash-off cosmetic products” means cosmetic products as defined in Article 2(1), point (a), of Regulation (EC) No 1223/2009 of the European Parliament and of the Council (*1) that, under normal conditions of use, are washed off with water after application; (b) for all cosmetic products other than the ones mentioned in paragraph 3(a), paragraph 1 shall apply after 6 June 2027.

Catalogue presence