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For further information, see CMDT Part 38-15 Acetaminophen
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Toxic dose: 150–200 mg/kg, but not to exceed 8–10 g (acute) or > 4 g/day (chronic)
Nausea, vomiting shortly after ingestion
Hepatic necrosis evident after 24–48 h
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Nausea or vomiting shortly after ingestion
Hepatic aminotransferase levels begin to increase 24–48 after ingestion; there are usually no other signs of toxicity
With severe poisoning, fulminant hepatic necrosis may occur, resulting in
Jaundice
Hepatic encephalopathy
Acute kidney injury
Death
Rarely, massive ingestion (eg, serum levels over 500–1000 mg/L [33–66 mmol/L]) can cause
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The diagnosis after acute overdose is based on measurement of the serum acetaminophen level
Plot the serum level versus the time since ingestion on the acetaminophen nomogram shown in Figure 38–1
Ingestion of sustained-release products or coingestion of an anticholinergic agent, salicylate, or opioid drug may cause delayed elevation of serum levels which can make interpreting the nomogram difficult
The nomogram is not useful after chronic or staggered overdose
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Oral activated charcoal (if given within 1–2 hours of acute ingestion)
Oral N-acetylcysteine (NAC), 140 mg/kg oral loading dose, followed by 70 mg/kg every 4 hours
Traditional US oral regimen 72 hours (17 doses), although equivalent success has been achieved with 20–48 hours of treatment
Intravenous NAC (Acetadote), 150 mg/kg administered over 60 minutes, then 50 mg/kg over 4 hours, then 100 mg/kg over 16 hour (21-hour infusion)
Treatment with N-acetylcysteine is most effective if it is started within 8–10 hours after ingestion
Hemodialysis is rarely indicated but might be needed in some patients with massive overdose