Acetaminophen poisoning

Acetaminophen poisoning is a common occurrence that results from an overdose of acetaminophen, a widely used over-the-counter analgesic and antipyretic. It is a significant cause of acute liver failure in many countries, including the United States and the United Kingdom.

Causes

Acetaminophen poisoning can occur as a result of either intentional overdose or unintentional misuse. Unintentional misuse can occur when a person takes more than the recommended dose in a 24-hour period, takes more than one acetaminophen-containing product at the same time, or combines acetaminophen with alcohol.

Symptoms

The symptoms of acetaminophen poisoning can be divided into four stages. The first stage, which occurs in the first 24 hours after ingestion, may include nonspecific symptoms such as nausea, vomiting, and malaise. The second stage, which occurs 24 to 72 hours after ingestion, is characterized by improvement in gastrointestinal symptoms but the onset of right upper quadrant pain. The third stage, which occurs 72 to 96 hours after ingestion, is characterized by recurrence of nausea and vomiting, along with the development of jaundice, coagulopathy, and encephalopathy. The fourth stage, which occurs 4 to 14 days after ingestion, is characterized by resolution of hepatic dysfunction in survivors.

Diagnosis

The diagnosis of acetaminophen poisoning is based on a history of recent acetaminophen ingestion and the presence of elevated serum acetaminophen levels. The Rumack-Matthew nomogram is a graphical tool used to predict the risk of hepatotoxicity based on the serum acetaminophen concentration and the time since ingestion.

Treatment

The mainstay of treatment for acetaminophen poisoning is N-acetylcysteine (NAC), which replenishes hepatic glutathione stores and enhances non-toxic metabolic pathways. NAC is most effective when administered within 8 hours of ingestion, but it can still be beneficial if started later.

Prevention

Prevention of acetaminophen poisoning involves education about the dangers of overdose and the importance of not exceeding the recommended dose. It is also important to avoid combining acetaminophen with alcohol or other drugs that can increase the risk of liver damage.