Undeceth-9
molecular structure · PubChem
AKA: Undecyl Alcohol Ethoxylate
Synthetic
Emollient
Cleanser
Emulsifier
Skin Conditioner
Not Clean
Poly(oxy-1,2-ethanediyl), .alpha.-hydroxy-.omega.-(undecyloxy)- (9 mol EO average molar ratio)
Effective at 1.6%
CAS #
9002-92-0; 68439-50-9; 5274-68-0; 9004-95-9; 9005-00-9; 4536-30-5; 3055-93-4; 3055-94-5; 3055-95-6
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.
Cleansing
Makes oil and water mix so dirt, makeup, and sunscreen can actually be washed away. The reason your face wash foams.
Emulsifying
Forces oil and water to stay mixed instead of separating into layers. The unsung hero holding your lotion together.
Locks In Moisture
Traditional Use
A non-ionic synthetic emulsifier developed through ethoxylation in the mid-20th century. Designed to improve the stability and sensory properties of cosmetic formulations.
EWG
4
CIR
Safe as used
Pregnancy
Yes
CIR Safety Findings
Not a Sensitizer
medical-approval
all-shades-safe
Concentration Guide
0.2%
3.0%
0%4%
Reported use
CIR reported use: 0.7-2 | 1-3 | 0.2-3
Regulatory Agencies
Skin Types
●all-skin-types
Best For
General
Pregnancy & Breastfeeding Safe
Yes
The paper trail
🔬Peer-reviewednone on file
⚖️Regulatory1 listing →
🛡️Safety-assessed1 review →
Counts, not a verdict. A listing isn't a study. The trail, you decide.
Verified Jun 2026
Data: CosIng · EWG · CIR