Acetaminophen is one of the most commonly used medications for pain and fever. The drug is marketed worldwide in both over-the-counter (OTC) and prescription formulations, and is found in combination with many other drugs. Aside from the fatal 1982 Tylenol tampering incident in Chicago, acetaminophen is considered very safe by the general public. However, acetaminophen use is not without risk.
Significance
According to 2009 information released from the U.S. Food and Drug Administration (FDA), acetaminophen toxicity is the number one cause of acute liver failure, accountable for approximately 400 deaths each year. Unintentional overdoses may occur because patients are unaware that acetaminophen is present in many common products. Alcohol consumption increases the risk of liver damage. Acetaminophen should not be used by anyone who drinks three or more alcoholic beverages daily.
Acetaminophen is Everywhere
Acetaminophen is found in many common products, both prescription and OTC. The FDA estimates nearly 600 products containing acetaminophen are currently marketed. While most consumers are aware acetaminophen is present in OTC pain relievers, the presence of the drug in prescription analgesic combinations, OTC cold medicines and sleep aids is often overlooked. Some prescription labels use abbreviations for acetaminophen such as "APAP." Pediatric acetaminophen formulations are available in several strengths, and, if mistakenly substituted, may lead to toxicity in infants or small children. The current maximum recommended dose of acetaminophen for adults is 4,000 mg per day.
How Liver Damage Occurs
Liver injury may occur even with low doses of acetaminophen. Cell damage occurs because small amounts of a toxic substance are produced when the liver metabolizes acetaminophen. Larger doses lead to larger amounts of the toxic substance. The ability of the liver to remove this substance before it permanently binds with liver proteins will determine the severity of the liver injury.
FDA Recommendations
Liver damage from acetaminophen is a growing public health concern. In June 2009, an advisory committee of the FDA issued recommendations including withdrawal of all prescription acetaminophen combination products and limiting pediatric products to a single strength. Lowering the maximum daily dose from 4,000 mg and the single adult dose to 650 mg was also recommended, although the new target maximum was not stated. The committee recommended unit-of-use packaging for all acetaminophen products and adding a severe, or "black-box" warning to products containing acetaminophen. The committee made the recommendations to the full FDA, but as of 2010, no official action has yet been taken. Many professional organizations and medical providers, including the American Association for the Study of Liver Diseases, are advising members and patients of the recommendations.
Prevention
Acetaminophen-induced liver damage is preventable. Patients must be aware of potential sources of acetaminophen and read all labels. Careful examination of products for children and verification of appropriate dosing is crucial. Cautious use of acetaminophen can prevent adverse outcomes.
References
- U.S. Food and Drug Administration: Advice for Patients: Help Patients Use Acetaminophen Safely.
- U.S. Food and Drug Administration: Acetaminophen Overdose and Liver Injury - Background and Options for Reducing Injury.
- American Association for the Study of Liver Diseases: FDA Advisory Panel Tightens Controls on Acetaminophen Products
