Sodium Isostearate

AKA: Sodium isooctadecanoate, ISOOCTADECANOIC ACID, SODIUM SALT (1:1), SODIUM ISOSTEARATE [INCI]
Plant-Derived
Cleanser
Emulsifier
Plant Oil
Clean
Isooctadecanoic acid, sodium salt
Formula
C18H35NaO2
Mol. Weight
306.50
CAS #
64248-79-9
Functions
Cleansing
Makes oil and water mix so dirt, makeup, and sunscreen can actually be washed away. The reason your face wash foams.
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.
Surfactant Cleansing
Surfactant Emulsifying
Anti-Inflammatory
Antimicrobial
Fights Acne
Removes dirt and impurities
Lifts away dirt and oil
Mixes oil and water
Traditional Use
A synthetic emulsifier derived from isostearic acid, developed in the mid-20th century for cosmetic formulations. Created to improve product stability and texture without traditional historical origins.
EWG
1
CIR
Safe as used
Pregnancy
Yes
CIR Safety Findings
Not a Sensitizer
medical-approval
all-shades-safe
Regulatory Status
USApermitted
EUrestricted
JAPANrestricted
CANADArestricted
Skin Types
all-skin-types
Best For
General
Pregnancy & Breastfeeding Safe
Yes
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.
Verified Jun 2026
Data: PubChem · CosIng · EWG · CIR