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Acetaminophen Overdose

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By Matt Vera BSN, R.N.


  • 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.


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 include:


  • 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.



  • 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.


  • 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.
Matt Vera, a registered nurse since 2009, leverages his experiences as a former student struggling with complex nursing topics to help aspiring nurses as a full-time writer and editor for Nurseslabs, simplifying the learning process, breaking down complicated subjects, and finding innovative ways to assist students in reaching their full potential as future healthcare providers.

7 thoughts on “Acetaminophen Overdose”

    • Hi Benson, You’re welcome! Thrilled to hear it’s serving as a useful tool for your revisions. If there’s anything else you need or more topics you want to dig into, just give a shout. Happy studying!

    • You’re welcome! Really glad to hear you found the notes helpful. If there’s anything else you need more info on or have questions about, just let me know. Here to help!

  1. i found this question somewhere in youtube with the same presentation. HOWEVER, the answer to the question was gastric lavage if ingestion was less than an hour followed by the antidote N acetylcysteine. The rationale behind was to remove first all that are still on the stomach before it could be absorbed and then administer the antidote which makes sense.

    can you clarify as to why acetylcysteine administration takes precedence over gastric lavage regardless of the time of ingestion? It was stated that GL is no longer practiced though.


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