PEG-8 Undecylenate

INCI: PEG-8 Undecylenate | Function: Surfactant, Emulsifier, Solubilizer | Type: PEG Ester

What Is PEG-8 Undecylenate?

PEG-8 Undecylenate is similar to PEG-6 Undecylenate but with a longer polyethylene glycol chain (8 EO units), giving it higher water solubility and milder surfactant properties. It functions as a gentle nonionic surfactant and emulsifier, carrying the antimicrobial properties of undecylenic acid. Commonly used in rinse-off formulations for sensitive skin.

Key Skin Benefits

+ Milder than PEG-6 variant — longer PEG chain reduces irritation potential
+ Excellent water solubility — good for transparent cleansers
+ Antimicrobial — undecylenic acid provides natural preservation support
+ Solubilizing — helps disperse fragrances and oils in water-based formulas

Pros

+ Very mild surfactant, compatible with sensitive skin formulations
+ Multifunctional — cleanser + emulsifier + antimicrobial in one
+ Water-soluble and easy to formulate with
+ Renewable castor oil derivative

Cons

− Ethoxylated — trace 1,4-dioxane concern requires purification
− Not suitable as primary surfactant (auxiliary role)
− Rinse-off only — limited leave-on applications

Specifications

Property	Value
Usage Areas	Face, Body, Hair
Product Type	Rinse-Off
Source	Semi-synthetic
Natural Level	Semi-synthetic

Safety Ratings

Metric	Rating
Skin Sensitivity	1/5
Comedogenic Rating	0/5
EWG Score	3/10

Regional Regulatory Limits

Region	Leave-on %	Rinse-off %	Status
EU (CosIng)	No limit	No limit	Allowed
US (CIR/FDA)	No limit	No limit	Allowed
Japan (MHLW)	No limit	No limit	Allowed
ASEAN	No limit	No limit	Allowed
China (NMPA)	No limit	No limit	Allowed

Typical Usage % by Product Type

Product Type	Typical %
Anti-dandruff shampoo	0.5 - 2%
Facial cleanser	0.5 - 3%
Micellar water	0.1 - 1%

References

CIR (2010) — Safety Assessment of PEGs as Used in Cosmetics. PMID: 20629512
CosIng (2025) — European Commission Database. https://ec.europa.eu/growth/tools-databases/cosing/
SpecialChem — PEG surfactant guide. https://cosmetics.specialchem.com/

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