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Polyisobutene
AKA “Polyisobutene”
Ingredient
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Ingredient Facts
Polyisobutene
Ingredient · Film Forming · EWG: 1
Plant-Derived Synthetic
Occlusive
Clean
Homopolymer of 2-methyl-1 propene
CAS #
9003-27-4
See origin →
Functions
Binding
Film Forming
Creates a physical seal on skin to lock moisture in and keep irritants out. The "slugging" ingredient — barrier protection.
Viscosity Controlling
Strengthens Barrier
Antioxidant
Anti-Inflammatory
Creates protective layer
Holds ingredients together
Controls product thickness
Traditional Use
Developed as a petroleum-derived synthetic polymer in the mid-20th century. Introduced to cosmetics as a conditioning and film-forming agent to improve texture and wear properties of skincare and color cosmetics.
Skin Types
●all-skin-types, gentle
Best For
Dryness
Pregnancy & Breastfeeding Safe
Yes
EWG
1
CIR
Safe as used
Pregnancy
Yes
CIR Safety Findings
Not a Sensitizer
ewg-1
medical-approval
pregnancy-nursing-safe
all-shades-safe
Regulatory Status
USA✔ permitted
EU⚠ restricted
JAPAN⚠ restricted
CANADA⚠ restricted
Final report of the cosmetic ingredient review expert panel on the safety assessment of Polyisobutene and Hydrogenated Polyisobutene as used in cosmet
International journal of toxicology, 2008
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Final report of the cosmetic ingredient review expert panel on the safety assessment of Polyisobutene and Hydrogenated Polyisobutene as used in cosmet
International journal of toxicology, 2008
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Final Report of the Cosmetic Ingredient Review Expert Panel on the on the safety assessment of Polyisobutene and Hydrogenated Polyisobutene as used in cosmetics
Cosmetic Ingredient Review (CIR) Expert Panel
International Journal of Toxicology
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Hydrogenated Polyisobutene
European Commission
EU Cosmetic Ingredient Database (CosIng)
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Polyisobutene
European Commission
EU Cosmetic Ingredient Database (CosIng)
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Skin moisturization by hydrogenated polyisobutene--quantitative and visual evaluation.
Dayan N, Sivalenka R, Chase J
Journal of cosmetic science, 2009
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Hydrogenated Polyisobutene
Environmental Working Group (EWG)
EWG Skin Deep Cosmetics Database
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Polyisobutene
Environmental Working Group (EWG)
EWG Skin Deep Cosmetics Database
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Drug release and adhesive properties of crospovidone-containing matrix patches based on polyisobutene and acrylic adhesives.
Schulz M, Fussnegger B, Bodmeier R
European journal of pharmaceutical sciences : official journal of the European Federation for Pharmaceutical Sciences, 2010
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Verified Jun 2026
Data: CosIng · EWG · CIR