What is a major risk factor for hepatotoxicity in patients taking INH?

A major risk factor for hepatotoxicity in patients taking isoniazid (INH) is indeed concurrent use of alcohol. Alcohol consumption can significantly increase the risk of liver damage in individuals taking this medication, primarily because both INH and alcohol are metabolized in the liver. When these substances are processed at the same time, it intensifies the burden on the liver and can lead to hepatocellular injury.

Furthermore, the combination of INH and alcohol can potentiate the toxic effects to the liver cells, leading to an increased likelihood of hepatotoxicity. This risk is particularly pronounced in patients with a history of heavy alcohol use, as they may already have compromised liver function or reduced liver reserve. Thus, it is crucial for healthcare providers to assess alcohol use in patients prescribed INH and to monitor liver function closely in these individuals.

Other factors, such as age, body mass index, and smoking status, may influence the risk of hepatotoxicity but do not carry the same degree of significant, documented risk as the concurrent use of alcohol, making it a critical point for patient care and risk assessment.