- N-acetyl cysteine (NAC) is made from the amino acid L-cysteine. It is a source of sulfhydryl (-SH) groups and, thus, may act as a strong antioxidant.
- Because it has the ability to thin mucus, NAC has been used traditionally as a decongestant. It has also been used to reduce poisoning associated with compounds such as acetaminophen and heavy metals.
- NAC has been used clinically for approximately 40 years and has shown benefit for treating bronchiolitis and chronic bronchitis. Recent study has investigated its role as an antioxidant with the potential to treat HIV infection, cancer, and heart conditions. There is a lack of evidence of benefit in using NAC to prevent kidney impairment or to treat hepatitis, cystic fibrosis, or erythropoietic protoporphyria (a disorder caused by a defect in making heme).
- NAC is generally well tolerated. The most frequent side effects are diarrhea, nausea, and vomiting. NAC is also well known for its unpleasant taste.