Acetaminophen overdose is the most common cause of liver failure in the US, and accidental overdoses (e.g. to manage pain) are associated with a greater risk of serious mortality or death. In a recent cohort study of patients who overdosed on acetaminophen (N=207), the mortality rate was 1% (with 2% receiving liver transplant). 76% of overdoses were intentional. Other studies have shown higher mortality rates, but these enrolled patients who had acute liver failure due to their overdose. NAC should be administered within 8 hours of ingestion for optimal effect.

Publication reference : Thusius NJ, Romanowicz M, Bostwick MJ. Intentional or inadvertent acetaminophen overdose-how lethal it really is? Psychosomatics 2019; 60: 574-581
Reference URL: https://www.ncbi.nlm.nih.gov/pubmed/31202442