Effect of acetylcysteine on prothrombin index in paracetamol poisoning without hepatocellular injury

Lancet. 2002 Oct 12;360(9340):1151-2. doi: 10.1016/S0140-6736(02)11194-9.


Acetylcysteine treatment reduces liver damage after paracetamol overdose, but can affect the prothrombin index, which is used to assess the progress of overdose patients. We aimed to assess retrospectively the effect of intravenous acetylcysteine on the prothrombin index in patients with paracetamol poisoning without signs of hepatocellular injury. Prothrombin index had been recorded before, and serially during, acetylcysteine treatment in 87 patients. After initiation of treatment, prothrombin index decreased (mean 0.33, 95% CI 0.29-0.38) in all patients, and was strongly associated with the start of acetylcysteine infusion. In patients with uncomplicated paracetamol poisoning, a fall in this index might be misinterpreted as a sign of liver failure, leading to prolonged treatment time.

MeSH terms

  • Acetaminophen / pharmacokinetics
  • Acetaminophen / poisoning*
  • Acetylcysteine / adverse effects
  • Acetylcysteine / therapeutic use*
  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Antidotes / adverse effects
  • Antidotes / therapeutic use*
  • Chemical and Drug Induced Liver Injury / blood
  • Chemical and Drug Induced Liver Injury / drug therapy*
  • Diagnosis, Differential
  • Drug Overdose / blood
  • Drug Overdose / drug therapy*
  • Female
  • Humans
  • Infusions, Intravenous
  • Liver Failure / blood
  • Liver Failure / chemically induced
  • Liver Failure / diagnosis
  • Male
  • Middle Aged
  • Prothrombin Time*
  • Retrospective Studies


  • Antidotes
  • Acetaminophen
  • Acetylcysteine