Cysteine (L-cysteine) is an amino acid that is a building block of proteins and is made by the body from another amino acid called methionine.
Cysteine occurs naturally in food, has antioxidant properties, is used in the manufacture of antioxidants, such as glutathione, so it can be used in the cosmetics industry.
People use cysteine to treat cancer, diabetes, hangovers, strokes, and many other conditions.

• White sulfurous solid.
• Stability Stable, but may be air sensitive. Incompatible with oxidizing agents, bases.