UMEM Educational Pearls

Category: Pharmacology & Therapeutics

Title: Consensus Statement on Managing Acetaminophen Poisoning

Keywords: Pharmacology, Toxicology, Acetaminophen, Acetylcysteine, NAC (PubMed Search)

Posted: 6/13/2024 by Matthew Poremba
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A panel comprised of 21 participants selected by four clinical toxicology societies (America’s Poison Centers, American Academy of Clinical Toxicology, American College of Medical Toxicology, and Canadian Association of Poison Control Centers) sought to develop consensus guidelines for management of acetaminophen poisoning in the US and Canada. Highlights from this framework include:

Acetylcysteine Stopping Criteria

A common misconception is that acetylcysteine is administered for 21 hours then discontinued. The consensus statement codifies the practice of reassessing the patient at the end of the acetylcysteine infusion and only stopping acetylcysteine if all of the following criteria are met:

  • Acetaminophen concentration <10 mcg/mL
  • INR <2.0
  • ALT/AST normal for patient or if elevated have decreased from peak (25%-50%)
  • Patient is clinically well

Ingestion of Extended-Release Acetaminophen Products

Extended release acetaminophen products are available on the US market. Management is largely the same as for instant release acetaminophen except for several exceptions:

  • Activated charcoal may be useful >4 hours after ingestion if acetaminophen concentration is rising (indicating ongoing absorption)
  • If a concentration drawn 4-12 hours after ingestion is >10 mcg/mL but below the Matthew-Romack treatment line, a second level should be drawn in four to six hours

Management of Repeated Supratherapeutic Acetaminophen Ingestion

When a patient presents following repeated acetaminophen ingestions over a period of greater than 24 hours the Matthew-Romack nomogram is no longer applicable for guiding decisions regarding treatment with acetylcysteine. The consensus statement recommends initiating treatment in this scenario if the patient’s acetaminophen concentration is > 20 mcg/mL or if patient’s AST/ALT are abnormal.

Final Thoughts:

These guidelines will function as a useful reference and officially codify a general framework with evidence-based recommendations for the management of acetaminophen poisoning. As always, a poison center or clinical toxicologist should be consulted for any complicated or serious acetaminophen poisoning.


Dart, Richard C et al. “Management of Acetaminophen Poisoning in the US and Canada: A Consensus Statement.” JAMA network open vol. 6,8 e2327739. 1 Aug. 2023, doi:10.1001/jamanetworkopen.2023.27739