What Is N-acetylcysteine Used For?

N-acetylcysteine, or NAC, is a form of the amino acid cysteine. The FDA has approved NAC to treat acetaminophen overdose. NAC's ability to thin mucus and its antioxidant properties have led to many off-label uses. The sulfur molecule in NAC makes the compound smell and taste like rotten eggs, but correct usage of the drug can help reverse liver failure, prevent kidney failure and make lung procedures much easier for both physician and patient.

Acetaminophen Overdose Antidote

Because N-acetylcysteine prevents acetaminophen metabolites from binding to liver cells, it is the treatment of choice for acute acetaminophen overdose. If treatment begins within eight hours of overdose, NAC is close to 100 percent effective in the prevention of liver damage. Because NAC acts as an antioxidant to reduce the number of liver cells that die, it is also effective for people with chronic acetaminophen overdoses and those with acute acetaminophen overdoses who don't get to an emergency facility within eight hours.

Liver Failure

N-acetylcysteine treats liver failure from other causes, including viral hepatitis and alcoholic cirrhosis. It increases blood flow to the smallest vessels of the liver, increases oxygen delivery and usage, and decreases the toxic effects of killer white blood cells. Use of the drug may increase survival rates and decrease the incidence of brain injury in liver patients.

Lung Disease

Because of its ability to thin secretions, N-acetylcysteine assists treatment of conditions such as asthma, chronic obstructive pulmonary disease and cystic fibrosis. It helps treat the pulmonary complications of surgery and helps in diagnostic lung procedures such as bronchoscopy, in which the physician sends a camera into the lungs.

Prevention of IV Contrast Kidney Failure

N-acetylcysteine helps prevent kidney damage resulting from intravenous contrast. The "Annals of Internal Medicine" published in February 2008 a meta-analysis of 41 studies. The analysis showed that NAC protects the kidneys from contrast-induced nephropathy. "Our data support the administration of N-acetylcysteine prophylaxis, particularly in high-risk patients, given its low cost, availability and few side effects," according to researcher A. M. Kelly and colleagues.

Other Uses

Off-label uses of n-acetylcysteine include the prevention of adverse effects from chemotherapy, heavy metal detoxification, ovulation induction in patients with polycystic ovary syndrome and the prevention of influenza. Studies on these uses are small, however, and as of March 2011 the FDA does not recommend NAC for these conditions.