N-acetyl cysteine is used as an antidote for acetaminophen and carbon monoxide poisoning. It is also used for unstable angina, common bile duct obstruction in infants, lysosomal storage disorders, amyotrophic lateral sclerosis (Lou Gehrig’s disease), Alzheimer’s disease, phenytoin-induced hypersensitivity, and keratoconjunctivitis. It is also used for reducing lipoprotein (a) levels, reducing homocysteine levels, reducing risk of cardiovascular events in patients with end-stage renal disease, chronic bronchitis, chronic obstructive pulmonary disease (COPD), allergic rhinitis, fibrosing alveolitis, head and neck cancer, and lung cancer. N-acetyl cysteine is also used orally for myoclonus epilepsy, otitis media, hemodialysis-related pseudoporphyria, chronic fatigue syndrome (CFS), Sjogren’s syndrome, preventing sports injury complications, radiation therapy, increasing immunity to flu and swine flu, and for detoxifying heavy metals such as mercury, lead, and cadmium. It is also used orally for preventing alcoholic liver damage, for protecting against environmental pollutants including carbon monoxide, chloroform, urethanes and certain herbicides, for reducing toxicity of ifosfamide and doxorubicin, as a hangover remedy, for preventing nonionic low-osmolality contrast agent-induced reduction of renal function in patients with renal insufficiency, for human immunodeficiency virus (HIV), and for trichotillomania (hair pulling).