murphyIsostearic Acid
AKA: Isooctadecanoic acid, 16-METHYLHEPTADECANOIC ACID, 2724-58-5, 30399-84-9, Heptadecanoic acid, 16-methylmargaric acid
Synthetic
Skin Conditioner
Synthetic
Clean
OriginDerived from plant oils, particularly through selective hydrogenation of oleic acid and related fatty acids. Produced by hydrogenating unsaturated plant-based fatty acids to create a saturated, branched-chain structure.
16-methylheptadecanoic acid is a methyl-branched fatty acid that is heptadecanoic acid (margaric acid) substituted by a methyl group at position 16. It is a long-chain fatty acid, a branched-chain saturated fatty acid and a methyl-branched fatty acid. It is functionally related to a heptadecanoic acid.
Formula
C18H36O2
Mol. Weight
284.50
CAS #
30399-84-9, 2724-58-5
Form
Liquid
State
Liquid; Liquid, Other Solid
Skin Types
●all-skin-types
Best For
Dryness
Pregnancy & Breastfeeding Safe
Yes
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.
Buffering
Holds Formula Together
Removes Impurities
Emulsifier
Cleansing Surfactant
The paper trail
🔬Peer-reviewed1 paper →
⚖️Regulatory0 listings
🛡️Safety-assessed3 reviews →
Counts, not a verdict. A listing isn't a study. The trail, you decide.
EWG
1
CIR
Safe
Pregnancy
Yes
CIR Safety Findings
Not a Sensitizer
5 studies / 5 not sensitizing (CIR 213 and 777)
Not Phototoxic
Animal test and Human test found no phototoxicity in the CIR safety assessment (CIR 213)
Mixed Eye Irritation Results
2 studies / 1 irritating / 1 mixed / reactions minimal (CIR 213 and 777)
Comedogenic in Testing
Product formulation test with a comedogenic result in the CIR safety assessment (CIR 213 and 777)
Mixed Skin Irritation Results
8 studies / 2 irritating / 3 mixed / 3 not irritating / reactions minimal to mild (CIR 213 and 777)
Concentration Guide
Leave-on0.012–16%
Rinse-off0.004–20%
0%50%100%
CIR reported use · 2016 survey
Regulatory Agencies
Verified Jun 2026
Data: PubChem · CosIng · EWG · CIR