Clinical Features at Various Stages of Acetaminophen Toxicity
Stage Clinical Features
Stage I — Preclinical
(0 to 24 hours)
• Minimal to no signs and symptoms
• Nausea, vomiting, general malaise
• Normal liver function tests (possibly)
Stage II — Hepatotoxicity
(24 to 72 hours)
• RUQ pain
• Elevations in AST, ALT
• Possible elevation in bilirubin and coagulation
studies (PT, PTT, INR)
Stage III — Hepatic failure
and encephalopathy
(72 to 96 hours)
• Liver function tests peak
• Jaundice
• Coagulopathy
• Encephalopathy
• Metabolic acidosis
• Pancreatitis (possibly)
• Acute renal failure (possibly)
Stage IV — Survival
or death (>96 hours)
• Full resolution or normalization of liver function
tests, or
• Fulminant liver failure, multiorgan dysfunction
and death
Adapted from Farcy DA, Chiu WC, Flaxman A, et al. Critical Care Emergency Medicine. 1st ed. New York, NY:

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