murphyPolyquaternium-51
molecular structure · PubChem
Synthetic
Occlusive
Skin Conditioner
Clean
OriginPolyquaternium-51 is a synthetic quaternary ammonium polymer derived from acrylamide and dimethylaminopropyl methacrylate monomers. It is synthesized through free radical polymerization of these monomers followed by quaternization to create the charged polymer.
2-(N,N,N-Trimethylamino)ethyl 2-(2-methyl-2-propenoyloxy)ethyl phosphate inner salt, polymer with butyl 2-methyl-2-propenoate
CAS #
125275-25-4
Form
Powder
Skin Types
●all-skin-types
Best For
General
Pregnancy & Breastfeeding Safe
Yes
Functions
Film Forming
Creates a physical seal on skin to lock moisture in and keep irritants out. The "slugging" ingredient — barrier protection.
Skin Conditioning
A catch-all term for ingredients that improve how skin looks and feels — softer, smoother, more supple. The workhorse behind most moisturizers.
Locks in moisture
The paper trail
🔬Peer-reviewednone on file
⚖️Regulatory1 listing →
🛡️Safety-assessed2 reviews →
Counts, not a verdict. A listing isn't a study. The trail, you decide.
EWG
1
CIR
Safe as used
Pregnancy
Yes
CIR Safety Findings
Not a Skin Irritant
2 studies / 2 not irritating (CIR 820)
Not a Sensitizer
3 studies / 3 not sensitizing (CIR 820)
Eye Irritant in Testing
1 study / 1 irritating / reactions slight (CIR 820)
Concentration Guide
Leave-on0.002–0.14%
Rinse-off0.000005–0.025%
0%50%100%
CIR reported use · 2020 survey
Regulatory Agencies
Verified Jun 2026
Data: CosIng · EWG · CIR