Be Vigilant About Acetaminophen (Tylenol) Toxicity
Acetaminophen (Tylenol), one of the most popular medications in the world, is used for the treatment of pain and fever. However, acetaminophen toxicity can lead to acute hepatic failure and the possible need for liver transplantation. The purpose of this article is to discuss acetaminophen toxicity.
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Acetaminophen, a medication used for the relief of pain and fever, is a common staple in medicine cabinets around the world and can be found in both over-the-counter (OTC) and prescription formulations. Outside of North America, acetaminophen is better known by the name paracetamol. Even though the brand Tylenol is the most popular acetaminophen-containing product, more than 200 other medications also contain this drug.
When taken at recommended doses, acetaminophen is usually safe and effective. However, this medication can be deadly when too much is taken. In fact, acetaminophen toxicity is the leading cause of acute hepatic failure in the industrialized world. Acetaminophen toxicity is the most common cause of hepatic failure requiring liver transplantation in Great Britain (Farrell, 2012). The majority of overdoses in the US, the UK, Australia, and New Zealand involve acetaminophen. In the United States, APAP toxicity has replaced viral hepatitis as the most common cause of acute hepatic failure and is the second most common cause of liver failure requiring transplantation (Farrell, 2012).
The signs and symptoms of acetaminophen toxicity are experienced by patients in three distinct stages. Many patients display no signs or symptoms of acetaminophen toxicity during the first phase, which is the initial 12 to 24 hours after the overdose. Some patients will experience general complaints such as malaise, nausea, vomiting, mild abdominal pain, and perspiration within a few hours after the overdose. For the next perhaps 12 to 24 hours, which is the second phase or the so-called inactive (latent) phase, the patient feels well (Lee, 2007).
During the third phase, which starts between 48 to 72 hours after the overdose, abnormal hepatic blood levels can be detected. Patients may continue to experience nausea and vomiting while beginning to experience right upper quadrant pain. Hepatic necrosis and dysfunction are associated with jaundice, coagulopathy, hypoglycemia, and hepatic encephalopathy (Farrell, 2012). Acute kidney failure sometimes develops during this third stage; in addition, some patients develop multiple organ failure and die.
For the average healthy adult, the recommended maximum dose of acetaminophen over a 24 hour period is four grams (4000 mg) or eight extra-strength pills (Lee, 2007). However, the patient who consumes more than two alcoholic beverages per day should not take more than two grams of acetaminophen in a 24-hour period. Any patient who has overdosed on acetaminophen must obtain prompt medical attention because interventions are most effective within the first eight hours after the last ingestion.
In addition, a Boxed Warning highlighting the potential for severe liver injury and a Warning highlighting the potential for allergic reactions (e.g., swelling of the face, mouth, and throat, difficulty breathing, itching, or rash) are being added to the label of all prescription drug products that contain acetaminophen (FDA, 2011).
Be sure to inform your patients that many OTC products contain acetaminophen, and reinforce to them that it may appear on the label as 'APAP.' Many patients are unknowingly taking multiple medications that contain acetaminophen, which can be dangerous. If we arm them with this knowledge, they can take the steps necessary to stay safe and prevent harm caused by overdose. Knowledge is power!
