Hydrogenated Polyisobutene

Hydrogenated Polyisobutene molecular structure
molecular structure · PubChem
AKA: UCUGLVJQUIRCPK-UHFFFAOYSA-N
Synthetic
Emollient
Skin Conditioner
Clean
Propene, 2-methyl-, homopolymer
CAS #
40921-86-6, 61693-08-1
Form
Powder
Skin Types
●all-skin-types
Best For
General
Pregnancy & Breastfeeding Safe
Yes
Functions
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.
Viscosity Controlling
Locks In Moisture
The paper trail
🔬Peer-reviewed1 paper →
⚖️Regulatory1 listing →
🛡️Safety-assessed2 reviews →
Counts, not a verdict. A listing isn't a study. The trail, you decide.
EWG
1
CIR
Safe as used
Pregnancy
Yes
CIR Safety Findings
Not Phototoxic
Product formulation test found no phototoxicity in the CIR safety assessment (CIR 455 and 687)
Not Comedogenic
Animal test found no comedogenicity in the CIR safety assessment (CIR 455)
Not a Sensitizer
8 studies / 8 not sensitizing (CIR 455)
Mixed Eye Irritation Results
9 studies / 2 irritating / 2 mixed / 5 not irritating / reactions slight to moderate (CIR 455 and 687)
Mixed Skin Irritation Results
18 studies / 2 irritating / 3 mixed / 13 not irritating / reactions minimal to mild (CIR 455 and 687)
Concentration Guide
Leave-on0.001–95%
Rinse-off0.00055–51%
0%50%100%
CIR reported use · 2013 survey
Regulatory Status
USA✔ permitted
EU⚠ restricted
JAPAN⚠ restricted
CANADA⚠ restricted
Verified Jun 2026
Data: CosIng · EWG · CIR