Cyclopentasiloxane
AKA “Silicone”
Emollient
Ingredient Facts
Cyclopentasiloxane
AKA: Silicone
Emollient · Emollient · EWG: 4
Synthetic
Emollient
Solvent
Skin Conditioner
Hair Care
Silicone
Not Clean
Decamethylcyclopentasiloxane
Formula
C10H30O5Si5
Mol. Weight
370.77
CAS #
541-02-6
Form
Liquid
State
Liquid
See origin →
Functions
Hair Conditioning
A catch-all term for ingredients that improve how skin looks and feels — softer, smoother, more supple. The workhorse behind most moisturizers.
Skin Conditioning
A catch-all term for ingredients that improve how skin looks and feels — softer, smoother, more supple. The workhorse behind most moisturizers.
Emollient
Fills in the tiny cracks between skin cells to make everything feel smooth and soft. The "silky finish" ingredient.
Solvent
Dissolves other ingredients so they distribute evenly in the formula. Often the invisible "base" everything else is mixed into.
Locks In Moisture
Traditional Use
A cyclic silicone polymer developed in mid-20th century silicone chemistry research. Used in cosmetics as a lightweight volatile carrier and emollient, designed to replace heavier traditional oils and waxes.
Skin Types
●all-skin-types
Best For
General
Pregnancy & Breastfeeding Safe
Yes
EWG
4
CIR
Safe as used
Pregnancy
Yes
Restricted By
CIR Safety Findings
medical-approval
all-shades-safe
Regulatory Agencies
Structural Similarity-Induced Inter-Component Interaction in Silicone Polymer-Based Composite Sunscreen Film for Enhanced UV Protection.
Chen Y, Xu H, Liu Y, Fu Q, Zhang P et al.
Polymers, 2024
Structural Similarity-Induced Inter-Component Interaction in Silicone Polymer-Based Composite Sunscreen Film for Enhanced UV Protection.
Chen Y, Xu H, Liu Y, Fu Q, Zhang P et al.
Polymers, 2024
Structural Similarity-Induced Inter-Component Interaction in Silicone Polymer-Based Composite Sunscreen Film for Enhanced UV Protection.
Chen Y, Xu H, Liu Y, Fu Q, Zhang P et al.
Polymers, 2024
Structural Similarity-Induced Inter-Component Interaction in Silicone Polymer-Based Composite Sunscreen Film for Enhanced UV Protection.
Chen Y, Xu H, Liu Y, Fu Q, Zhang P et al.
Polymers, 2024
Structural Similarity-Induced Inter-Component Interaction in Silicone Polymer-Based Composite Sunscreen Film for Enhanced UV Protection.
Chen Y, Xu H, Liu Y, Fu Q, Zhang P et al.
Polymers, 2024
Safety Assessment of Polysilicone-11 as Used in Cosmetics.
Cherian P, Bergfeld WF, Belsito DV, Cohen DE, Klaassen CD et al.
International journal of toxicology, 2024
Safety assessment of Cyclomethicone, Cyclotetrasiloxane, Cyclopentasiloxane, Cyclohexasiloxane and Cycloheptasiloxane
Cosmetic Ingredient Review (CIR) Expert Panel
International Journal of Toxicology
Safety Assessment of Polysilicone-11 as Used in Cosmetics
Cosmetic Ingredient Review (CIR) Expert Panel
International Journal of Toxicology
Cyclopentasiloxane
European Commission
EU Cosmetic Ingredient Database (CosIng)
Polysilicone-11
European Commission
EU Cosmetic Ingredient Database (CosIng)
Cyclopentasiloxane
Environmental Working Group (EWG)
EWG Skin Deep Cosmetics Database
Polysilicone-11
Environmental Working Group (EWG)
EWG Skin Deep Cosmetics Database
Addressing the Structural Organization of Silicone Alternatives in Formulations by Molecular Dynamics Simulations and a Novel Equilibration Protocol.
Ferreira T, Loureiro A, Noro J, Cavaco-Paulo A, Castro TG
Polymers, 2023
Safety assessment of cyclomethicone, cyclotetrasiloxane, cyclopentasiloxane, cyclohexasiloxane, and cycloheptasiloxane.
Johnson W Jr, Bergfeld WF, Belsito DV, Hill RA, Klaassen CD et al.
International journal of toxicology, 2011
Safety assessment of cyclomethicone, cyclotetrasiloxane, cyclopentasiloxane, cyclohexasiloxane, and cycloheptasiloxane.
Johnson W Jr, Bergfeld WF, Belsito DV, Hill RA, Klaassen CD et al.
International journal of toxicology, 2011
Safety assessment of cyclomethicone, cyclotetrasiloxane, cyclopentasiloxane, cyclohexasiloxane, and cycloheptasiloxane.
Johnson W Jr, Bergfeld WF, Belsito DV, Hill RA, Klaassen CD et al.
International journal of toxicology, 2011
Effects of silicone emulsifiers on in vitro skin permeation of sunscreens from cosmetic emulsions.
Montenegro L, Paolino D, Puglisi G
Journal of cosmetic science, 2004
Design and Characterization of Silicone and Surfactant Based Systems for Topical Drug Delivery.
Oyafuso MH, Carvalho FC, Chiavacci LA, Gremião MP, Chorilli M
Journal of nanoscience and nanotechnology, 2015
Design and Characterization of Silicone and Surfactant Based Systems for Topical Drug Delivery.
Oyafuso MH, Carvalho FC, Chiavacci LA, Gremião MP, Chorilli M
Journal of nanoscience and nanotechnology, 2015
Verified Jun 2026
Data: PubChem · CosIng · EWG · CIR