What is the maximum daily dose of acetaminophen for most adults, and which organ is at risk with overdose?

• A. 3000 mg; kidney
• B. 2000 mg; heart
• C. 4000 mg; liver
• D. 5000 mg; liver

Answer: (D)

The key idea is understanding safe daily dosing and what happens in an overdose. For most adults, the recommended maximum is 4000 mg (4 grams) of acetaminophen in a 24-hour period. Overdose increases the risk of serious liver injury because the liver is the primary organ responsible for metabolizing acetaminophen. A portion of the drug is converted to a toxic metabolite (NAPQI). When taken within the normal dose, glutathione neutralizes this metabolite. If you exceed the limit, glutathione stores can be overwhelmed, allowing NAPQI to accumulate and damage liver cells, potentially causing acute liver failure. So the organ at risk with overdose is the liver, not the kidney or the heart.