Prescription acetaminophen gets new limit, warnings

Prescription drugs that contain combinations of acetaminophen and other medications will be required to contain no more than 325 mg of acetaminophen per tablet or capsule, the FDA recently announced.

The limit will be phased in over the next three years. In addition, a boxed warning on the potential for severe liver injury and a warning on the potential for allergic reactions (e.g., swelling of the face, mouth, and throat; difficulty breathing; itching; or rash) will be added to the labels of these drugs.

Acetaminophen is one of the most commonly used drugs in the United States, and between 1998 and 2003 it was the leading cause of acute liver failure in the country, with 48% of acetaminophen-related cases (131 of 275) associated with accidental overdose, the FDA announcement said. The new regulations are intended to reduce the risk of severe liver injury and allergic reactions associated with acetaminophen, as well as making it less likely that patients will overdose if they mistakenly take too many doses of acetaminophen-containing products.

Clinicians should educate patients about the importance of reading all prescription and over-the-counter (OTC) labels to ensure they are not taking multiple acetaminophen-containing products, the FDA advised. Patients should also be advised not to drink alcohol while taking acetaminophen and not to exceed the maximum total daily dose of 4 g/d. Dosing of combination medications will not need to change in response to the reformulations. For example, if a product that previously contained 500 mg of acetaminophen with an opioid and was prescribed as 1 to 2 tablets every 4 to 6 hours is reformulated to contain 325 mg of acetaminophen, the dosing instructions can remain unchanged, the FDA said.

OTC products containing acetaminophen are not affected by this action, and the FDA is continuing to evaluate ways to reduce the risk of acetaminophen-related liver injury from OTC products, according to the announcement.