Acetaminophen: a new foe?
Anita Aminoshariae, DDS, MS, and Asma Khan, BDS, PhD
- The Food and Drug Administration (FDA) Drug Safety Communication states that ‘‘acetaminophen-containing prescription products are safe and effective when used as directed, though all medications carry some risks’’ (2).
- During the past decade, acetaminophen has been identified as the leading cause of acute liver failure in the United States, and up to 50% of the cases are caused by an unintentional overdose (3–6).
- In 2011, confirming acetaminophen as a dose-dependent hepatotoxin, the FDA asked drug manufactures to limit the strength of acetaminophen in prescription drug products (e.g., acetaminophen-opioid combinations) to 325 mg per tablet, capsule, or other dosage unit (2).
- In 2014, the FDA called on health care professionals to discontinue prescribing and dispensing prescription combination drug products with more than 325 mg acetaminophen (8). Ultimately, on March 26, 2014, the FDA and the pharmaceutical industry took action to protect consumers from the risk of severe liver damage by formally withdrawing from the market all prescription combination drug products with more than 325 mg acetaminophen (9).
- Recent evidence also suggests that acetaminophen has significant adverse effects when taken at recommended doses during pregnancy. If this reflects causality, the safety of acetaminophen during pregnancy must be questioned.
- A clearer understanding of these mechanisms holds the key to reducing acetaminophen-related adverse effects while optimizing analgesia.
Purpose of the Article
To discuss new issues related to safety, labeling, dosing, and a better understanding of the anti-nociceptive action of acetaminophen.
- While acetaminophen is generally considered a very safe drug, there are no ‘‘absolutely’’ safe biologically active therapeutic agents (i.e., drugs seldom exert their beneficial effects without the potential for also causing side effects).
- Even with therapeutic doses, acetaminophen can cause adverse drug events in certain conditions such as chronic alcohol use, malnutrition, and polypharmacy (4).
- Indiscriminate consumption of acetaminophen can cause acute liver failure, trigger hormone disruption in pregnant patients, increase the risk of asthma in children, cause serious allergic reaction and toxicity, potentiate the effect of warfarin, and increase the risk of hematologic malignancies.
- To prevent these side effects, consumers and practitioners need to be well informed and be aware of the total maximum recommended daily dose.