Acetaminophen Overdose

Definition

• Acetaminophen poisoning is an overdose of the over-the-counter (OTC) pain medication, acetaminophen (eg, Tylenol, Biogesic), which is usually safe when used as recommended.
• The maximum daily dose of acetaminophen is four (4) grams, but patients with chronic diseases (especially liver disease) may need to limit themselves to three (3) grams a day.
• Acetaminophen poisoning may occur as a result of one large dose or chronic overdoses.

Causes

An overdose of acetaminophen can result from:

• Intentional overdose (eg, suicide attempt)
• Accidental overdose (eg, unsupervised children, altered judgment regarding appropriate acetaminophen intake)
• Combining medications that contain acetaminophen (Acetaminophen is found in more combination products than any other drug; examples include acetaminophen and codeine, as well as acetaminophen and aspirin.)
• Toxic levels of acetaminophen may also occur in patients with liver failure who are taking recommended doses

Risk Factors

The following factors increase your chance of developing acetaminophen poisoning:

• Age: 15-24 years or older than 40 years (People over 40 are more likely to have severe effects.)
• Gender: female
• Suicidal behavior

Symptoms

Symptoms include:

• Nausea
• Vomiting
• Excessive sweating
• Pale skin
• Symptoms of liver failure:
  • Anorexia
  • Nausea
  • Vomiting
  • Malaise
  • Abdominal pain (especially in the upper right portion of the abdomen)
  • Pale skin
  • Excessive sweating
  • Jaundice
  • Confusion
  • Stupor

Diagnosis

• Blood Tests—Blood tests are done to determine the level of acetaminophen in your blood and to determine liver function (eg, liver enzyme tests, coagulation tests).
• Rumack-Matthew Nomogram—This is an assessment to determine the effect on the liver. The test measures blood levels of acetaminophen relative to the time since ingestion of the medication.

Treatment

Monitoring

• For children who have relatively low levels of acetaminophen in their blood, monitoring at home may be recommended.

Activated Charcoal

• Activated charcoal can help prevent acetaminophen from absorbing in the gastrointestinal tract. It is taken by mouth.

N-acetylcysteine

• In most cases of toxic acetaminophen overdose, N-acetylcysteine, an amino acid, will be given by mouth or IV (through the vein) as an antidote.