Educational Pearls:   Acetaminophen overdose can also present in patients taking too much over the course of days to weeks - not just intentional ingestions If acute overdose is suspected, refer to the Rumak-Matthew nomogram to guide treatment based on time of ingestion and the time of level In chronic overdose, Tylenol levels will not guide treatment NAPQI is the toxic metabolite of acetaminophen N-acetylcysteine (NAC) can be effective treatment in both acute and chronic overdoses 7.5 g is the daily toxic dose of Tylenol in adults, 150mg/kg in children     References: Smilkstein MJ. Acetaminophen. In: Goldfrank's Toxicologic Emergencies, Goldfrank LR, Flomenbaum NE, Lewin NA, et al (Eds), Appleton & Lange, Stamford 1998. P.541. Chiew AL, Gluud C, Brok J, Buckley NA. Interventions for paracetamol (acetaminophen) overdose. Cochrane Database Syst Rev. 2018 Feb 23;2:CD003328. doi: 10.1002/14651858.CD003328.pub3. Review. PubMed PMID: 29473717. Lancaster EM, Hiatt JR, Zarrinpar A. Acetaminophen hepatotoxicity: an updated review. Arch Toxicol. 2015 Feb;89(2):193-9. doi: 10.1007/s00204-014-1432-2. Epub 2014 Dec 24. Review. PubMed PMID: 25537186. Summarized by Will Dewispelaere, MS3 | Edited by Erik Verzemnieks, MD