Management of Possible Acetaminophen Overdose in a 1-Year-Old
Administer N-acetylcysteine (NAC) immediately without waiting for laboratory confirmation if there is any suspicion of toxic acetaminophen ingestion in this 1-year-old child, as treatment within 8 hours prevents severe hepatotoxicity in over 97% of cases. 1, 2
Immediate Actions (Do Not Delay)
Start NAC immediately if any of the following apply:
- Reported ingestion of ≥150 mg/kg in a single dose 1
- Repeated doses totaling ≥150 mg/kg per day for 2+ days 1, 3
- Any suspicion of toxic ingestion even with uncertain dosing history 3, 2
- The child appears ill with vomiting, lethargy, or abdominal pain after acetaminophen exposure 4
Critical timing window: Treatment within 8 hours results in only 2.9% severe hepatotoxicity, versus 26.4% when started after 10 hours. 1, 3, 2
Initial Assessment Protocol
Draw blood immediately for:
- Acetaminophen level (if ≥4 hours post-ingestion) 5
- AST, ALT, bilirubin, INR/PT 5
- Creatinine, BUN, glucose, electrolytes 5
Important caveat: The Rumack-Matthew nomogram does not apply to children under 12 years per ACEP guidelines, and cannot be used for repeated supratherapeutic ingestions. 6, 3 Treatment decisions in young children must be based on total dose ingested, clinical presentation, and laboratory evidence of hepatotoxicity. 1, 3
NAC Dosing for Pediatric Patients
Oral NAC regimen (preferred if child can tolerate):
- Loading dose: 140 mg/kg orally 5
- Maintenance: 70 mg/kg every 4 hours for 17 additional doses (total 72 hours) 3, 5
- Dilute 20% solution to 5% with juice or soft drink 5
- If vomiting occurs within 1 hour, repeat that dose 5
IV NAC regimen (if unable to tolerate oral):
- Loading: 150 mg/kg IV over 15 minutes 3, 2
- Second dose: 50 mg/kg over 4 hours 3, 2
- Third dose: 100 mg/kg over 16 hours 3, 2
Activated Charcoal Consideration
Give activated charcoal (1 g/kg) if:
- Presentation is within 4 hours of ingestion 3, 2
- Child can protect airway 1
- Do not delay NAC while administering charcoal 2
- Give charcoal just prior to starting NAC 3, 2
Special Considerations for Young Children
Lower threshold for toxicity: Children under 6 years may develop severe hepatotoxicity with doses as low as 90 mg/kg/day when given repeatedly over multiple days. 4 A case report documented fulminant liver failure in a 5-year-old after 90 mg/kg/day for 3 consecutive days. 4
Repeated supratherapeutic ingestion criteria requiring NAC:
- ≥150 mg/kg per day for ≥2 days 1, 3
- Any detectable acetaminophen level with AST/ALT >50 IU/L 3
- Clinical signs of hepatotoxicity regardless of reported dose 1, 4
When to Continue or Extend NAC Beyond Standard Protocol
Continue NAC beyond 72 hours if:
- AST/ALT remain elevated or rising 3, 2
- INR remains elevated 3, 2
- Acetaminophen level still detectable 3, 2
- Clinical signs of hepatotoxicity persist 1, 3
NAC can be discontinued only when ALL of the following are met:
- Acetaminophen level undetectable 3, 2
- AST/ALT normal or declining 3, 2
- INR normal 3, 2
- Patient clinically well 3, 2
Critical Pitfalls to Avoid
Do not rely on reported dose alone: Plasma acetaminophen levels are more reliable than dose estimates for assessing risk. 7 However, low or absent levels do not rule out toxicity if ingestion was remote or occurred over several days. 1, 3
Do not wait for symptoms: Children may appear well initially despite ongoing hepatic injury. 4, 8 The latent period before clinical hepatotoxicity can last 24-72 hours. 8
Do not withhold NAC for uncertain history: If there is any suspicion of toxic ingestion and the child presents within 24 hours, start NAC immediately. 1, 2, 5 Even when started late (>24 hours), NAC reduces mortality from 80% to 52% in fulminant hepatic failure. 1, 2
Monitoring and Disposition
Repeat labs every 24 hours until:
ICU admission required if:
Contact transplant hepatology immediately if severe hepatotoxicity develops (AST/ALT >1,000 IU/L with coagulopathy). 1, 3