POLYQUATERNIUM-51 is graded A (Safe) by Expert·ING, based on COSING, FDA regulatory data.

POLYQUATERNIUM-51

Safety grade: A

This is a synthetic polymer that acts like a lightweight coating for your skin and hair. It helps create a smooth, protective layer that locks in moisture and improves how products feel on your skin.

This ingredient forms a breathable film on the skin's surface to improve hydration and smoothness while providing a silky, conditioned feel to cosmetic products.

Graded using: COSING, FDA.

Last verified: May 26, 2026