C18-38 Alkyl C24-54 Acid Ester
AKA “C18-38 Alkyl C24-54 Acid Ester, Alkyl Ester
Synthetic
Ingredient Facts
C18-38 alkyl c24-54 acid ester
AKA: Alkyl Ester
Synthetic · Emollient · EWG: 4
Synthetic
Emollient
Skin Conditioner
Synthetic
Clean
A lightweight texture enhancer that keeps formulas smooth and easy to apply without feeling heavy or greasy on skin.
CAS #
223706-22-7
Form
Oil
State
Solid
See origin →
Functions
Viscosity Controlling
Emollient
Fills in the tiny cracks between skin cells to make everything feel smooth and soft. The "silky finish" ingredient.
Skin Conditioning
A catch-all term for ingredients that improve how skin looks and feels — softer, smoother, more supple. The workhorse behind most moisturizers.
Controls Viscosity
Traditional Use
A synthetic long-chain ester created for modern cosmetic chemistry in the 20th century. Developed as a non-comedogenic emollient for premium skincare formulations.
Skin Types
all-skin-types
Best For
Dryness
Melanin-Rich Skin
Suitable
Pregnancy & Breastfeeding Safe
Yes
EWG
4
CIR
Insufficient
Pregnancy
Yes
CIR Safety Findings
Not a Sensitizer
medical-approval
all-shades-safe
Regulatory Status
USAunder review
EUrestricted
JAPANrestricted
CANADArestricted
Final Safety Assessment of Thiodipropionic Acid and its Dialkyl Esters as Used in Cosmetics
Cosmetic Ingredient Review (CIR) Expert Panel
International Journal of Toxicology
Safety Assessment of Alkyl Esters as Used in Cosmetics
Cosmetic Ingredient Review (CIR) Expert Panel
International Journal of Toxicology
C18-38 Alkyl C24-54 Acid Ester
European Commission
EU Cosmetic Ingredient Database (CosIng)
Crotonic Acid/Vinyl C8-12 Isoalkyl Esters/VA/Bis-Vinyldimethicone Crosspolymer
European Commission
EU Cosmetic Ingredient Database (CosIng)
Final safety assessment of thiodipropionic acid and its dialkyl esters as used in cosmetics.
Diamante C, Fiume MZ, Bergfeld WF, Belsito DV, Hill RA et al.
International journal of toxicology, 2010
Final safety assessment of thiodipropionic acid and its dialkyl esters as used in cosmetics.
Diamante C, Fiume MZ, Bergfeld WF, Belsito DV, Hill RA et al.
International journal of toxicology, 2010
Final safety assessment of thiodipropionic acid and its dialkyl esters as used in cosmetics.
Diamante C, Fiume MZ, Bergfeld WF, Belsito DV, Hill RA et al.
International journal of toxicology, 2010
Final safety assessment of thiodipropionic acid and its dialkyl esters as used in cosmetics.
Diamante C, Fiume MZ, Bergfeld WF, Belsito DV, Hill RA et al.
International journal of toxicology, 2010
Final safety assessment of thiodipropionic acid and its dialkyl esters as used in cosmetics.
Diamante C, Fiume MZ, Bergfeld WF, Belsito DV, Hill RA et al.
International journal of toxicology, 2010
Final safety assessment of thiodipropionic acid and its dialkyl esters as used in cosmetics.
Diamante C, Fiume MZ, Bergfeld WF, Belsito DV, Hill RA et al.
International journal of toxicology, 2010
Crotonic Acid/Vinyl C8-12 Isoalkyl Esters/VA/Bis-Vinyldimethicone Crosspolymer
Environmental Working Group (EWG)
EWG Skin Deep Cosmetics Database
Verified Feb 2026
Data: CosIng · EWG · CIR