N-Acetylcysteine (NAC) is an acetylated variant of the amino acid L-cysteine. It is well established as a medication for acetaminophen overdose due to its ability to replenish intracellular glutathione and act as an antioxidant. In the context of cirrhosis of the liver, scientific interest in NAC comes from its antioxidant properties and potential to reduce oxidative stress, which is a key factor in the progression of chronic liver diseases, including cirrhosis.

Some clinical studies and animal models have explored the use of NAC in chronic liver disease. There is evidence suggesting that NAC administration may improve certain liver function parameters, reduce oxidative injury, and decrease inflammation in patients with chronic hepatitis and cirrhosis. However, these studies are generally small, with mixed results, and meta-analyses have noted that while NAC is safe, its benefit in established cirrhosis is modest and not consistently significant. The strongest evidence for NAC in liver conditions is for acute liver failure, particularly acetaminophen-induced, rather than cirrhosis per se.

In summary, while there is a scientific rationale and some low to moderate quality evidence supporting the use of NAC for cirrhosis (primarily through its antioxidant effects), the overall strength of evidence is limited, and guidelines do not currently recommend NAC as a standard therapy for cirrhosis.