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Quaternium-18
AKA “Dimethyl dioctadecyl ammonium chloride, Stearalkonium chloride”
Surfactant
Ingredient Facts
Quaternium-18
AKA: Dimethyl dioctadecyl ammonium chloride, Stearalkonium chloride
Surfactant · Cleansing · EWG: 3
Synthetic
Cleanser
Skin Conditioner
Hair Care
Plant Oil
Not Clean
Quaternary ammonium compounds, bis(hydrogenated tallow alkyl)dimethyl, chlorides
CAS #
61789-80-8
Form
Liquid
See origin →
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
Traditional Use
A quaternary ammonium compound developed in the mid-20th century as a synthetic conditioning and antistatic agent for hair and skincare products. Designed to replace natural oils while providing improved stability and consumer appeal.
Skin Types
●all-skin-types
Best For
General
Pregnancy & Breastfeeding Safe
Yes
EWG
3
CIR
Safe as used
Pregnancy
Yes
CIR Safety Findings
Not a Sensitizer
medical-approval
all-shades-safe
Regulatory Status
USA✔ permitted
EU⚠ restricted
JAPAN⚠ restricted
CANADA⚠ restricted
Quaternium-18 and Quaternium-18 Bentonite.
Cherian P, Bergfeld WF, Belsito DV, Klaassen CD, Liebler DC et al.
International journal of toxicology, 2023
→
Quaternium-18 and Quaternium-18 Bentonite.
Cherian P, Bergfeld WF, Belsito DV, Klaassen CD, Liebler DC et al.
International journal of toxicology, 2023
→
Quaternium-18 and Quaternium-18 Bentonite.
Cherian P, Bergfeld WF, Belsito DV, Klaassen CD, Liebler DC et al.
International journal of toxicology, 2023
→
Final Report on the Safety Assessment of Quaternium-18, Quaternium-18 Hectorite, and Quaternium-18 Bentonite
Cosmetic Ingredient Review (CIR) Expert Panel
International Journal of Toxicology
→
Final Report on the Safety Assessment of Stearalkonium Chloride
Cosmetic Ingredient Review (CIR) Expert Panel
International Journal of Toxicology
→
Quaternium-18 and Quaternium-18 Bentonite
Cosmetic Ingredient Review (CIR) Expert Panel
International Journal of Toxicology
→
Quaternium-18
European Commission
EU Cosmetic Ingredient Database (CosIng)
→
Quaternium-18 Bentonite
European Commission
EU Cosmetic Ingredient Database (CosIng)
→
Quaternium-18 Hectorite
European Commission
EU Cosmetic Ingredient Database (CosIng)
→
Quaternium-18/Benzalkonium Bentonite
European Commission
EU Cosmetic Ingredient Database (CosIng)
→
Stearalkonium Chloride
European Commission
EU Cosmetic Ingredient Database (CosIng)
→
Quaternium-18
Environmental Working Group (EWG)
EWG Skin Deep Cosmetics Database
→
Quaternium-18 Bentonite
Environmental Working Group (EWG)
EWG Skin Deep Cosmetics Database
→
Quaternium-18 Hectorite
Environmental Working Group (EWG)
EWG Skin Deep Cosmetics Database
→
Stearalkonium Chloride
Environmental Working Group (EWG)
EWG Skin Deep Cosmetics Database
→
Verified Jun 2026
Data: CosIng · EWG · CIR