History and exam
Key diagnostic factors
common
attempted self-harm
There may be a history of previous attempted self-harm or overdose.[15][21][22][36]
Most conscious patients will offer a history of acetaminophen ingestion. It is helpful to establish the amount ingested, and the time of the first and last dose, as this will affect subsequent management. If the history is highly discordant with the measured concentration, clinical suspicion may arise regarding the patient’s account of when, and how much, acetaminophen was ingested. Delayed absorption should also be considered.
Co-ingestion of other drugs is common and this history should be specifically sought.
repeated use of nonprescription analgesics for pain relief
Most conscious patients will offer a history of acetaminophen ingestion. It is helpful to establish the amount ingested, and the time of the first and last dose, as this will affect subsequent management.
A common reason for poisoning via repeated supratherapeutic ingestion is dental pain.[15][16][17]
Co-ingestion of other drugs is common and this history should be specifically sought.
asymptomatic presentation
Many patients who present within the first 24 hours will be asymptomatic.
nausea, vomiting, or abdominal pain
uncommon
right upper quadrant pain and tenderness
Signs of hepatotoxicity typically develop 1 to 3 days after ingestion.
jaundice
Signs of hepatotoxicity typically develop 1 to 3 days after ingestion.
confusion, decreased consciousness level, and/or asterixis
Indicate fulminant hepatic failure.
May develop 3 to 4 days after ingestion.[53][54][55][56][57]
Rarely, massive overdose of acetaminophen may initially present with coma and metabolic acidosis prior to development of hepatotoxicity.[55]
Coma may also be present if a combination formulation of acetaminophen and an opioid has been taken or there has been co-ingestion of drugs (including alcohol) that reduce the consciousness level.
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