Acetaminophen Toxicity

IMPORTANT: It is best to refer to your local hospital protocol for management of acetaminophen toxicity or call DPIC . The below resources should be used to support your learning. 

Emergency Care BC

• Overview of management of acetaminophen toxicity including pathophysiology, expected presentation and treatment recommendations

Acetaminophen Nomogram

• Tool used to determine if N-acetylcysteine is indicated 

1. Which of the following best describes the mechanism behind acetaminophen toxicity? 

a) Acetaminophen gets metabolized by CYP2E1 to NAPQI which gets converted to toxic mercapturic acid 

b) Acetaminophen gets metabolized by CYP2E1 to NAPQI which covalently binds to liver 

c) Acetaminophen is metabolized by UDP-glucuronosyl to glucuronate, a toxic metabolite 

d) Acetaminophen is metabolized by sulfotransferase to a toxic metabolite  

2. Which of the following is NOT a clinical finding consistent with acetaminophen toxicity? 

a) Abdominal pain 

b) Elevated liver enzymes 

c) Low INR

d) Elevated serum creatinine  

3. The following individuals are at risk of acetaminophen toxicity EXCEPT? 

a) Malnourished 

b) Concurrent use of CYP inhibitors 

c) Alcoholics 

d) Codeine use 

4. N-acetylcysteine is indicated in the following situations EXCEPT?  

a) Patient with acetaminophen (APAP) level above the treatment line based on the nomogram 

b) Patient who ingested 30g of APAP 2 hours ago

c) Patient with elevated liver enzymes, INR and jaundice  

d) Patient in a coma 

5. What is the typical duration of N-acetylcysteine infusion? 

a) 1 hour

b) 12 hours

c) 21 hours

d) 24 hours