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Acetaminophen overdose — MCCQE Part 1 MCQ

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HardPoisoning/OverdoseAcetaminophen overdoseMCCQE Part 1

A 23-year-old woman presents 10 hours after taking 24 tablets of 500 mg acetaminophen. She has nausea, normal mental status, ALT is mildly elevated, and the acetaminophen level is above the treatment line on the nomogram. What is the most appropriate next step in management?

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Correct answer: A — Start N-acetylcysteine immediately

N-acetylcysteine is indicated when the acetaminophen concentration is above the treatment line, and benefit is greatest when started early but remains important after 8 hours. Activated charcoal alone is inadequate at 10 hours. A normal INR early after overdose does not exclude evolving hepatotoxicity.

Reference: Ontario Poison Centre acetaminophen guidance