AMIDINOCYSTEINE is graded A (Safe) by Expert·ING, based on COSING regulatory data.

AMIDINOCYSTEINE

Safety grade: A

Amidinocysteine is a modified amino acid (a building block of proteins) that is used to chemically alter the structure of hair. It helps break down the bonds that give hair its natural shape so that hair can be restyled into waves or straightened.

This ingredient is used in hair waving and straightening products to chemically restructure hair by breaking protein bonds, allowing the hair to be permanently set into a new wave pattern or straightened form.

Graded using: COSING.

Last verified: May 26, 2026