N-acetyl Cysteine Comes From The Amino Acid L-cysteine. Amino Acids Are The Building Blocks Of Proteins. N-acetyl Cysteine Has Many Uses As Medicine.N-acetyl Cysteine Is Most Commonly Used By Mouth For Cough And Other Lung Conditions. It Is Also Used For Flu, Dry Eye, And Many Other Conditions, But There Is No Good Scientific Evidence To Support Many Of These Uses.... Read more