murphyQuaternium-18
AKA: Dimethyl dioctadecyl ammonium chloride, Stearalkonium chloride
Synthetic
Cleanser
Skin Conditioner
Hair Care
Not Clean
OriginDerived from coconut or palm kernel oil fatty alcohols, belonging to the quaternary ammonium compound family. Synthesized through quaternization of dimethylaminopropylamine with stearyl chloride or similar alkyl halides.
Quaternary ammonium compounds, bis(hydrogenated tallow alkyl)dimethyl, chlorides
CAS #
61789-80-8
Form
Liquid
Skin Types
●all-skin-types
Best For
General
Pregnancy & Breastfeeding Safe
Yes
Functions
Antistatic
Hair Conditioning
A catch-all term for ingredients that improve how skin looks and feels — softer, smoother, more supple. The workhorse behind most moisturizers.
Cleansing
Makes oil and water mix so dirt, makeup, and sunscreen can actually be washed away. The reason your face wash foams.
Reduces Static
Conditions Hair
Cleansing Surfactant
Locks In Moisture
Lifts away dirt and oil
Reduces flyaways
Softens and detangles hair
The paper trail
🔬Peer-reviewed1 paper →
⚖️Regulatory1 listing →
🛡️Safety-assessed3 reviews →
Counts, not a verdict. A listing isn't a study. The trail, you decide.
EWG
3
CIR
Safe as used
Pregnancy
Yes
CIR Safety Findings
Mixed Eye Irritation Results
3 studies / 2 irritating / 1 not irritating / reactions minimal (CIR 241)
Mixed Skin Irritation Results
4 studies / 2 irritating / 1 mixed / 1 not irritating / reactions mild (CIR 241)
Mixed Sensitization Results
1 study / 1 mixed (CIR 241)
Concentration Guide
Leave-on0.46%
Rinse-off0.76–0.95%
0%50%100%
CIR reported use · 2018 survey
Regulatory Agencies
Verified Jun 2026
Data: CosIng · EWG · CIR