N-Acetyl Cysteine (NAC) has strong scientific support for its use in supporting the hepatic (liver) system, especially in clinical settings. The most prominent, well-validated application is as an antidote for acetaminophen (paracetamol) toxicity, which is one of the most common causes of acute liver failure worldwide. NAC acts as a precursor to glutathione, a major endogenous antioxidant in the liver, and helps replenish glutathione stores that become depleted during toxic injury. This, in turn, helps neutralize reactive metabolites and prevents or minimizes liver cell damage.

Numerous clinical trials and systematic reviews have confirmed that timely administration of NAC significantly reduces liver injury and improves survival in cases of acetaminophen overdose. In some studies, NAC has also shown benefit in non-acetaminophen acute liver failure and in certain chronic liver diseases due to its antioxidant and anti-inflammatory properties, although evidence in these contexts is less robust and more research is needed.

Due to its well-established mechanism of action and extensive clinical validation, NAC is included in treatment guidelines for acetaminophen poisoning by organizations such as the American Association for the Study of Liver Diseases (AASLD) and the World Health Organization (WHO). Thus, scientific evidence for NAC's hepatic support, especially in toxic injury contexts, is strong and widely recognized.