Paeds · acute-care-resuscitation-and-toxicology
Paracetamol poisoning
Also known as Acetaminophen poisoning in children · Paracetamol overdose · N-acetylcysteine for paracetamol toxicity · Rumack-Matthew nomogram · Paracetamol-induced hepatotoxicity
A fellowship approach to paediatric paracetamol poisoning: take a focused time-of-ingestion history, plot a single acute ingestion on the Rumack-Matthew nomogram at four hours using the 150 mg per litre treatment line, give activated charcoal early when indicated, and start intravenous N-acetylcysteine when the level is on or above the treatment line, when the ingestion is staggered or of unknown time, or when hepatotoxicity is already present. Give NAC empirically when in doubt, watch the ALT and the coagulation trend, and escalate to a liver unit the moment King's College criteria are met.
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Target exams
Red flags
- A staggered or unknown-time ingestion must never be plotted on the nomogram: treat with N-acetylcysteine empirically
- A paracetamol level drawn before four hours cannot be interpreted on the nomogram: repeat at four hours or later
- A rising ALT with a falling and normalising paracetamol level is the hallmark of evolving hepatotoxicity and is not recovery
- A coagulopathy (rising INR), acidosis or envenomed encephalopathy signals established liver failure: escalate to a liver transplant centre
- Repeated supratherapeutic dosing in a febrile, fasting or vomiting child can cause hepatotoxicity even without a single large overdose
- Call the local poisons information centre early: dosing, treatment-line choice and duration are protocol-dependent and region-specific
Life stages
Care settings
Clinical exam formats
Board mappings
- Acute Care
- Current 2026 PREP curriculum — Learning Objective 2.4.4: Assess and manage infants, children and young people with potential cardiac, respiratory or neurological emergencies or acute sepsis
- Current 2026 PREP curriculum — Learning Objective 2.2.3: Perform acute resuscitation and advanced life support
- Current 2026 PREP curriculum — Learning Objective 2.2.1: Recognise, prioritise and manage an acutely ill infant, child or young person
- Renewed curriculum for first-year trainees from 2027 — Learning goal 11: Acute care and procedures
- Renewed curriculum for first-year trainees from 2027 — Learning goal 17: Acute care
- Clinical Applications
- Medical Sciences
- Long Cases
- Short Cases
- 4. Professional skills and knowledge: Patient management
- 7. Patient safety, including safe prescribing
- General Paediatrics: Resuscitates, stabilises and treats extremely unwell babies, children and young people, liaising with specialist teams, as necessary
- General Paediatrics: Assumes the role of Acute Paediatric Team Leader
- Applied Knowledge in Practice (AKP)
- Theory and Science (TAS)
- Clinical
- History
- Communication
- Video
- General Pediatrics Content Outline — Domain 7: Emergency and Critical Care
- General Pediatrics Content Outline — Universal Task 4: Management and Treatment
- General Pediatrics EPA 7: Recognizing a Severely Ill Patient, Providing Initial Management, and Mobilizing Resources Needed for Continued Care
- Patient Care 5: Patient Management
- Patient Care 4: Clinical Reasoning
- Systems-Based Practice 1: Patient Safety
- Medical Expert
- Pediatrics: Core EPA #2 — Resuscitating and stabilizing critically ill patients
- Pediatrics: Foundations EPA #1 — Recognizing deteriorating and/or critically ill patients and initiating stabilization and management
Overview & Definition
Paracetamol (acetaminophen) poisoning is the most common paediatric poisoning presentation worldwide and remains a leading, preventable cause of acute liver failure. At therapeutic doses paracetamol is safely conjugated by the liver, but after an overdose the conjugation pathways saturate and a greater fraction is metabolised by cytochrome P450 2E1 into the reactive intermediate N-acetyl-p-benzoquinone imine (NAPQI). NAPQI is normally detoxified by glutathione, but once glutathione is depleted it binds hepatocytes and causes centrilobular necrosis. The antidote, N-acetylcysteine (NAC), works by restoring glutathione and by directly conjugating NAPQI, and it is most effective when given early. [1] [2]
The decisive clinical skill is therefore not memorising doses but taking an accurate time-of-ingestion history and using the Rumack-Matthew nomogram correctly. The nomogram relates the serum paracetamol concentration to the time after a single acute ingestion, and the treatment line decides whether NAC is indicated. It is valid only for a single acute ingestion with a known time, and only for a level drawn at four hours or later. A staggered ingestion (multiple doses over hours), an unknown-time ingestion, a repeated supratherapeutic dosing history, or a level drawn before four hours cannot be plotted on the nomogram and demand a different decision rule. [1] [4]
The modern approach treats paracetamol poisoning as a protocolised, region-dependent pathway. The treatment line, the NAC regimen and the threshold to treat staggered ingestions differ between guidelines, and the local poisons information centre or toxicology service should be consulted early. The principles, however, are universal: estimate risk from the history, measure the level at the right time, give NAC when indicated, monitor the liver and coagulation trend, and escalate when liver failure develops. [2] [4]
References12ShowHide
- [1]Rumack BH Acetaminophen hepatotoxicity: the first 35 years Journal of toxicology. Clinical toxicology, 2002.PMID 11990202
- [2]Bateman DN, Dart RC, Dear JW, et al. Fifty years of paracetamol (acetaminophen) poisoning: the development of risk assessment and treatment 1973-2023 with particular focus on contributions published from Edinburgh and Denver Clinical toxicology (Philadelphia, Pa.), 2023.PMID 38197864
- [3]Prescott LF Paracetamol (acetaminophen) poisoning: The early years British journal of clinical pharmacology, 2024.PMID 37683599
- [4]Sivilotti MLA, Yarema MC, Juurlink DN Treating acetaminophen overdose CMAJ : Canadian Medical Association journal = journal de l'Association medicale canadienne, 2022.PMID 35440504
- [5]Watson CJ, Simpson MD, Saraiya N, et al. N-Acetylcysteine Dose and Treatment Duration in High-Risk Acetaminophen Ingestions Treated Within Eight Hours: A Retrospective Cohort Study Journal of medical toxicology : official journal of the American College of Medical Toxicology, 2026.PMID 41857443
- [6]Moss MJ, Hinchman B, Lambson JE, et al. Assessment of high-dose acetylcysteine in acute high-risk paracetamol (acetaminophen) ingestion Clinical toxicology (Philadelphia, Pa.), 2024.PMID 39051728
- [7]James LP, Alonso EM, Hynan LS, et al. Detection of acetaminophen protein adducts in children with acute liver failure of indeterminate cause Pediatrics, 2006.PMID 16950959
- [8]Squires RH Jr, Shneider BL, Bucuvalas J, et al. Acute liver failure in children: the first 348 patients in the pediatric acute liver failure study group The Journal of pediatrics, 2006.PMID 16737880
- [9]Daoud A, Dalhoff KP, Christensen MB, et al. Two-bag intravenous N-acetylcysteine, antihistamine pretreatment and high plasma paracetamol levels are associated with a lower incidence of anaphylactoid reactions to N-acetylcysteine Clinical toxicology (Philadelphia, Pa.), 2020.PMID 31601129
- [10]Harrison PM, O'Grady JG, Keays RT, et al. Serial prothrombin time as prognostic indicator in paracetamol induced fulminant hepatic failure BMJ (Clinical research ed.), 1990.PMID 2249026
- [11]Karabacak B, Özaydın E Clinical characteristics and outcomes of pediatric paracetamol poisoning presenting to the emergency department BMC pediatrics, 2026.PMID 41998668
- [12]Vincent F, Thompson J, Gray L, et al. Medication errors involving intravenous paracetamol in children: experience from enquiries to the National Poisons Information Service Archives of disease in childhood, 2024.PMID 38233098