From the Guidelines
Acetaminophen overdose is a medical emergency that requires immediate treatment with N-acetylcysteine (NAC) to reduce the risk of hepatotoxicity and mortality, ideally within 8 to 10 hours of ingestion, as recommended by the Annals of Emergency Medicine 1. The effects of an acetaminophen overdose can be severe and potentially life-threatening, with the primary concern being liver damage.
- The toxic dose is generally considered to be more than 150 mg/kg in adults or more than 4 grams in 24 hours.
- Initial symptoms may include nausea, vomiting, and abdominal pain, while liver damage symptoms (jaundice, confusion, bleeding) typically appear 24-72 hours later.
- The Rumack-Matthew nomogram is used to determine the risk of hepatotoxicity, and NAC should be administered to patients with either possible or probable risk for hepatotoxicity, as determined by the nomogram, to reduce the incidence of severe hepatotoxicity and mortality 1.
- Treatment typically involves activated charcoal if within one hour of ingestion, followed by NAC administration, usually as an intravenous infusion over 21 hours.
- Blood tests will be done to check paracetamol levels, liver function, and kidney function to monitor the patient's condition and adjust treatment as needed.
- Recovery is likely with prompt treatment, but delayed treatment can lead to liver failure requiring transplantation or even death, emphasizing the importance of immediate medical attention in cases of suspected acetaminophen overdose.
From the FDA Drug Label
The acute ingestion of acetaminophen in quantities of 150 mg/kg or greater may result in hepatic toxicity. Values above the solid line connecting 200 mcg/mL at least 4 hours with 50 mcg/mL at 12 hours are associated with a possibility of hepatic toxicity if an antidote is not administered.
The effects of an acetaminophen overdose include hepatic toxicity. An overdose of 150 mg/kg or greater may result in liver damage. The risk of hepatotoxicity is determined by plasma or serum acetaminophen concentrations, which should be measured as early as possible, but no sooner than 4 hours following the overdose 2.
From the Research
Effects of Acetaminophen Overdose
- Acetaminophen overdose is a common cause of hepatotoxicity in the Western World 3
- The toxic effects of acetaminophen most often occur in the liver and kidneys, and can also impair phosphate and lactate turnover 4
- Acetaminophen poisoning can induce temporary liver dysfunction or even irreversible liver failure, with liver transplantation as the only therapeutic possibility 4
- Chronic alcoholics are especially at risk, as liver damage may occur following acetaminophen even in recommended doses 4
Treatment of Acetaminophen Overdose
- Activated charcoal, gastric lavage, and ipecacuanha are able to reduce the absorption of acetaminophen, but the clinical benefit is unclear 3, 5
- N-acetylcysteine seems preferable to placebo/supportive treatment, dimercaprol, and cysteamine, but N-acetylcysteine's superiority to methionine is unproven 3, 5
- N-acetylcysteine may reduce mortality in patients with fulminant hepatic failure 3, 5
- Co-administration of N-acetylcysteine and acetaminophen can efficiently block acetaminophen toxicity 6
- A triple strategy of N-acetylcysteine, fomepizole, and early hemodialysis may be beneficial in massive acetaminophen overdose 7
Management of Acetaminophen Overdose
- Current management of paracetamol poisoning worldwide involves the administration of intravenous or oral acetylcysteine, which is based mainly on observational studies 5
- Results from observational studies indicate that treatment with acetylcysteine seems to result in a decrease in morbidity and mortality 5
- Further evidence from randomized clinical trials comparing different treatments is needed to determine the best course of action 3, 5