Cyclotetrasiloxane
AKA “Cyclotetrasiloxane, Oktamethylcyklotetrasiloxan, Cyclic dimethylsiloxane tetramer, NUC silicone VS 7207, Union carbide 7207”
Synthetic
Ingredient Facts
Cyclotetrasiloxane
AKA: Oktamethylcyklotetrasiloxan, Cyclic dimethylsiloxane tetramer, NUC silicone VS 7207, Union carbide 7207
Synthetic · Emollient · EWG: 4
Synthetic
Emollient
Solvent
Skin Conditioner
Hair Care
Silicone
Synthetic
Clean
A lightweight conditioning agent that smooths hair and skin while helping other ingredients blend seamlessly into the formula.
Formula
H8O4Si4
Mol. Weight
184.40
CAS #
556-67-2, 293-51-6
Form
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.
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 oligomer synthesized in the mid-20th century. Developed for cosmetics as an ultra-lightweight volatile emollient and spreading agent offering a silky feel superior to traditional plant oils.
Skin Types
●all-skin-types
Best For
General
Melanin-Rich Skin
Suitable
Pregnancy & Breastfeeding Safe
Yes
EWG
4
CIR
Safe w/Qualifications
Pregnancy
Yes
CIR Safety Findings
medical-approval
all-shades-safe
Regulatory Agencies
Final Report: Safety Assessment of Polymerized Tetramethylcyclotetrasiloxanes as Used in Cosmetics
Cosmetic Ingredient Review (CIR) Expert Panel
International Journal of Toxicology
Safety assessment of Cyclomethicone, Cyclotetrasiloxane, Cyclopentasiloxane, Cyclohexasiloxane and Cycloheptasiloxane
Cosmetic Ingredient Review (CIR) Expert Panel
International Journal of Toxicology
Cyclotetrasiloxane
European Commission
EU Cosmetic Ingredient Database (CosIng)
Cyclotetrasiloxane
Environmental Working Group (EWG)
EWG Skin Deep Cosmetics Database
Safety assessment of cyclomethicone, cyclotetrasiloxane, ...
Wilbur Johnson, Wilma F Bergfeld, Donald V Belsito, Ronald A Hill, Curtis D Klaassen, Daniel C Liebler + 5 more
International journal of toxicology, 2011
Safety assessment of cyclomethicone, cyclotetrasiloxane, ...
Wilbur Johnson, Wilma F Bergfeld, Donald V Belsito, Ronald A Hill, Curtis D Klaassen, Daniel C Liebler + 5 more
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
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
Verified Feb 2026
Data: PubChem · CosIng · EWG · CIR