CYSTEINE is graded A (Safe) by Expert·ING, based on COSING, FDA regulatory data.
CYSTEINE
Safety grade: A
Cysteine is an amino acid (a building block of protein) that your body naturally produces. In cosmetics, it's often used to strengthen hair and protect products from breaking down.
This ingredient protects cosmetic products and hair from damage caused by environmental stress, reduces unwanted odors, conditions hair, and can be used in hair straightening or waving treatments to help reshape hair structure.
Graded using: COSING, FDA.
Last verified: May 26, 2026
Other Antioxidant ingredients
- TOCOPHEROL — Grade A
- TOCOPHERYL ACETATE — Grade A
- BHT — Grade C**
- ASCORBYL PALMITATE — Grade A
- HYDROXYACETOPHENONE — Grade A
- PENTAERYTHRITYL TETRA-DI-T-BUTYL HYDROXYHYDROCINNAMATE — Grade A
- ASCORBIC ACID — Grade A
- CAMELLIA SINENSIS LEAF EXTRACT — Grade A