Ever since people have been using acetaminophen as a pain reliever, the drug has come with the caution that using too much of it can damage the liver. In recent years more careful study has found that acetaminophen is more toxic and in lower doses than previously recognized. Acetaminophen is now recognized as the predominant cause of liver damage and liver failure. The FDA’s new guidance for prescription drugs recommends limiting the dosage to 325 milligrams per capsule:
FDA is recommending health care professionals discontinue prescribing and dispensing prescription combination drug products that contain more than 325 milligrams (mg) of acetaminophen per tablet, capsule, or other dosage unit. There are no available data to show that taking more than 325 mg of acetaminophen per dosage unit provides additional benefit that outweighs the added risks for liver injury. Further, limiting the amount of acetaminophen per dosage unit will reduce the risk of severe liver injury from inadvertent acetaminophen overdose, which can lead to liver failure, liver transplant, and death.
Most U.S. cases of liver failure are linked to accidental overdoses of acetaminophen, but even recommended doses of acetaminophen carry a slight risk of serious liver damage or liver failure. It is probably safest to assume that every dose of acetaminophen causes liver stress that could reduce liver function, increasing body toxicity and potentially contributing to a wide range of other illnesses. For such a common drug, this is a significant public health problem. The FDA says it plans to withdraw approval for prescription drugs that contain more than 325 mg of acetaminophen, and it will address over-the-counter drugs separately. It is the prescription drugs that pose the greatest danger of overdose, though: patients sent home in a post-surgical fog may not read the fine print on the prescription pain relievers they are taking. It may not occur to them that the drugs contain acetaminophen at all.