Acetaminophen is metabolized by an enzyme in the liver. This is also true of many other medications, including other analgesics, anticonvulsants, antifungal agents, antibiotics and other drugs. As a result, it is easy to overwhelm the liver’s ability to metabolize these agents, which can frequently lead to overdose. Accidental and intentional overdose of acetaminophen are so common that hospital emergency rooms have protocols in place for dealing with these emergencies.

Symptoms of acetaminophen overdose can be similar to the medication’s side effects but are usually more severe. Overdose of acetaminophen can lead to toxicity and even death. Patients should always consult their physician before taking acetaminophen or any other medication.

Symptoms or conditions that may result from acetaminophen overdose include:

• Sweating.
  
  
• Stomach pain, cramps, vomiting or diarrhea.
  
  
• Fever.
  
  
• Anemia.
  
  
• Bluish discoloration of the skin (cyanosis).
  
  
• Irregular heartbeat.
  
  
• Skin eruptions.
  
  
• Seizures.
  
  
• Shock.
  
  
• • Delirium. Temporary state of mental confusion and fluctuating consciousness.
    
    
  • Hepatoxicity. Toxic damage to the liver.
    
    
  • Jaundice. Yellowish discoloration of the whites of the eyes, skin, and mucous membranes.
    
    
  • Methemoglobinemia. Presence of the brownish–red form of hemoglobin known as methemoglobin that progresses to depression of the central nervous system.
    
    
• Coma.

Toxicity due to acetaminophen overdose usually occurs in several stages. The first stage occurs 12 to 24 hours after ingestion. Patients exhibiting any of these symptoms during this stage should contact their physician immediately:

• Loss of appetite (anorexia)
• Excessive perspiration (diaphoresis)
• Nausea or vomiting
• Malaise

Stage two occurs 24 to 48 hours after ingestion, and includes symptoms such as abdominal pain and decreased urine output. In stage three (72 to 96 hours after ingestion), liver toxicity reaches its peak and is accompanied by flu–like symptoms, jaundice, low blood sugar (hypoglycemia), impaired consciousness, kidney failure, heart problems and abnormal clotting. Recovery takes place in stage four, seven to eight days after ingestion.

Overdose is treated by giving the patient ipecac syrup (medication that induces vomiting), activated charcoal (medication that neutralizes poisons that have been swallowed) or gastric lavage (washing out the stomach with sterile water or a salt–water solution). In some cases, the drug may be removed from the body through dialysis, a procedure to remove toxic substances or metabolic wastes from the bloodstream.