The Lab
Specimen No. 0028
CautionSyntheticemollient

Dimethicone / Cyclomethicone

dimethicone · cyclomethicone · cyclopentasiloxane

Silicone-based ingredients that create a smooth, protective film on skin and hair. Generally non-toxic to humans but cyclomethicone (D4/D5) is environmentally persistent.

high confidence
Researched April 18, 2026

Concerns

  • Cyclomethicone (D4/D5) is PBT (persistent, bioaccumulative, toxic) to aquatic organisms
  • EU restricts D4 and D5 in wash-off products
  • May impede skin breathability with heavy use
  • Some users report buildup on hair with repeated use

Commonly found in

MoisturizerPrimerFoundationHair serumConditioner

Research disclaimer: This rating is based on available peer-reviewed research and regulatory assessments at the time of publication. It is not medical advice. Consult a qualified professional for personal health or skin concerns.

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