When many of us get a headache, a fever, or just suffer the aches and pains of physical exertion we don’t think twice about reaching for an over-the-counter pain reliever. Acetaminophen, which is the medicine in the well-known brand Tylenol, has long been considered the safest pain medication. Non-steroidal anti-inflammatory medications (NSAIDs) can cause stomach irritation and ulcers and can decrease kidney function. Opiates (morphine and its relatives) can cause drowsiness, constipation and addiction. Acetaminophen has none of these side effects and remains the first choice of many physicians when safety (not efficacy) is paramount.
But yesterday an FDA working group released a report reminding us that even acetaminophen has risks. Specifically, acetaminophen in high doses can cause serious, even fatal, liver injury. Liver injury can happen at even lower doses in people who drink alcohol regularly or who have other liver diseases. Every year some people die of liver failure due to acetaminophen overdose. Some of these overdoses are intentional, and some are due to misunderstanding medications with multiple ingredients. For example, some prescription medicines like Vicodin and Percocet contain an opiate pain medicine and also acetaminophen. Patients who don’t know this and take Tylenol in addition may inadvertently take a dangerously high dose of acetaminophen.
The FDA working group recommended limiting the maximum adult daily dose of acetaminophen to no more than 3,250 mg. (It’s currently 4,000 mg.) The maximum dose should be even lower for patients drinking 3 or more alcoholic drinks daily. The group also recommended eliminating the “extra strength” tablet dose of 500 mg and limiting tablets to 325 mg and single adult doses to a maximum of 650 mg.
I still think acetaminophen is the safest available pain reliever. We all need to be more careful about keeping track of the ingredients in the over-the-counter and prescription medicines we take, and in the case of acetaminophen, we need to keep a close eye on our total daily dose.
ABC News article: FDA Group Issues Cautions on Acetaminophen Overdose
FDA report: Recommendations for FDA Interventions to Decrease the Occurrence of Acetaminophen Hepatotoxicity (The report is 286 pages long. I recommend reading the executive summary on the fifth page.)