What is the treatment for acetaminophen (Tylenol) overdose in pediatric patients?

Treatment of Acetaminophen Overdose in Pediatric Patients

N-acetylcysteine (NAC) is the definitive treatment for acetaminophen overdose in pediatric patients and should be administered as soon as possible, ideally within 8-10 hours of ingestion, to reduce the risk of hepatotoxicity, liver failure, and mortality. 1

Initial Assessment and Risk Stratification

• Obtain a plasma or serum acetaminophen concentration at least 4 hours after ingestion

• Use the Rumack-Matthew nomogram to determine risk for hepatotoxicity for acute single ingestions with:

  • Known time of ingestion
  • Presentation within 24 hours of ingestion
  • Serum level drawn at least 4 hours post-ingestion 2, 1

• Important: The Rumack-Matthew nomogram should NOT be used for:

  • Chronic ingestions or repeated supratherapeutic ingestions
  • Unknown time of ingestion
  • Presentation >24 hours after ingestion 3

NAC Treatment Protocol

Indications for NAC:

• Acetaminophen levels in "possible risk" or "probable risk" zones on nomogram
• Unknown time of ingestion with concerning acetaminophen level
• Presentation >8 hours after ingestion with concerning history
• Evidence of hepatotoxicity regardless of acetaminophen level
• Repeated supratherapeutic ingestions 1, 4

IV NAC Administration (preferred in pediatric patients):

1. Loading dose: 150 mg/kg diluted in appropriate solution over 15-60 minutes
2. First maintenance dose: 50 mg/kg over 4 hours
3. Second maintenance dose: 100 mg/kg over 16 hours

Total dose: 300 mg/kg over 21 hours 4

Oral NAC Alternative (if IV access unavailable):

• Loading dose: 140 mg/kg
• Maintenance dose: 70 mg/kg every 4 hours for 17 doses 1

Additional Management Considerations

• For patients presenting within 4 hours of ingestion, administer activated charcoal before starting NAC 1
• For massive overdoses (>500 mg/kg), consider adjunctive treatments:
  • Fomepizole
  • Hemodialysis (in cases with refractory metabolic acidosis or extremely high levels) 5
• Monitor:
  • Liver function tests (AST, ALT)
  • Coagulation studies (PT/INR)
  • Renal function
  • Electrolytes and glucose 6

Treatment Duration and Endpoints

• Standard duration: 21 hours for IV protocol
• Consider continuing treatment beyond 21 hours if:
  • Persistent elevation of acetaminophen levels
  • Worsening or elevated liver enzymes
  • Coagulopathy or encephalopathy 1, 4
• Treatment may be discontinued when:
  • Acetaminophen level is undetectable
  • Liver enzymes are normal or improving
  • Patient is clinically stable 1

Special Scenarios

Chronic or Repeated Supratherapeutic Ingestion

• Do not use the Rumack-Matthew nomogram
• Evaluate with serum acetaminophen level, liver function tests, and coagulation studies
• Administer NAC if:
  • Any detectable acetaminophen level
  • Elevated liver enzymes
  • Clinical evidence of hepatotoxicity 3

Delayed Presentation (>24 hours)

• Administer NAC regardless of acetaminophen level if there is:
  • History of significant ingestion
  • Evidence of hepatotoxicity 2, 1

Prognosis and Follow-up

• Early NAC administration (within 8-10 hours) is associated with excellent outcomes and minimal hepatotoxicity 2
• Delayed treatment (>10 hours) increases risk of hepatotoxicity but NAC still beneficial 2
• Most pediatric patients receiving appropriate NAC treatment recover completely without long-term sequelae 4, 7
• Psychiatric evaluation is essential for intentional overdoses, as studies show high rates of psychiatric comorbidities (89% of cases) 7

Pitfalls to Avoid

• Delaying NAC administration while waiting for acetaminophen levels in high-risk scenarios
• Using the Rumack-Matthew nomogram for repeated supratherapeutic ingestions
• Failing to recognize that children under 6 years typically have better outcomes than adolescents, but still require appropriate evaluation and treatment 8
• Underestimating the risk of hepatotoxicity in cases of unintentional repeated supratherapeutic dosing, which can lead to fulminant hepatic failure 6, 3

Early recognition and prompt administration of NAC remain the cornerstones of successful management of acetaminophen overdose in pediatric patients.