Acetaminophen Poisoning

Also Know As Paracetamol Poisoning

Acetaminophen (Paracetamol) Poisoning

Acetaminophen poisoning (also called paracetamol toxicity) is due to excessive use of the pharmaceutical analgesic drug paracetamol, known as acetaminophen in the United States. Damage to the liver (hepatotoxicity) is the main effect, and it is consequently the most common cause of acute hepatic failure in many areas of the world.

The toxic dose of paracetamol varies between individuals. For adults, single doses in excess of 10g or 200mg/kg of body weight – whichever is lower – are likely sufficient to cause toxicity.

Causes

Certain factors have the potential to increase the risk of developing acetaminophen poisoning. These include:

•         Frequent heavy alcohol consumption;
•         Fasting; and
•         Simultaneous, large doses of paracetamol and caffeine.

Symptoms and diagnosis

Signs of acetaminophen poisoning appear in stages. The first occurs within hours of overdose, and is characterised by nausea, vomiting and paleness. In severe cases, patients may lose consciousness and fall into coma.

Several days after ingestion, symptoms indicating increased liver damage will appear, such as:

•          Right upper-quadrant pain (signalling necrosis of cells in the liver);
•          Jaundice;
•          Hepatic encephalopathy (severely depressed level of consciousness due to liver damage); and
•          Multiple organ failure.

The most effective method of diagnosis involves testing the paracetamol concentration in the drug. This process is usually taken at least four hours following ingestion, to prevent any underestimation due to unabsorbed paracetamol still in the gastrointestinal tract.

Treatment

Gastric decontamination is usually the first form of treatment for acetaminophen poisoning, involving the administration of activated charcoal to absorb paracetamol from the gastrointestinal tract. This is most effective if performed within two hours of ingestion, during which the natural process of paracetamol absorption into the bloodstream occurs.

Alternatively, gastric lavage – more commonly known as stomach pumping – may be considered for considerably larger doses.

For patients suffering, or expected to die from, hepatic failure, a liver transplantation may also be recommended. 

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