The FDA is taking steps to more closely regulate acetaminophen, issuing an official warning that doses over 325mg may hurt your liver. The FDA is asking doctors to stop prescribing "combination" drugs that contain more than that amount per dose—pain medications including Percocet, Vicodin, and codeine often contain acetaminophen, and patients who've been given those drugs may not realize it, CNN reports. That could lead to a dangerous situation in which they end up taking another drug containing acetaminophen, like Tylenol, thus ingesting an unsafe amount of the drug.
Almost half of all acetaminophen-related cases of liver failure in the US are caused by accidental overdose, Reuters reports. But the FDA warning does not apply to over-the-counter drugs; those will be addressed at a later date. For now, the agency also plans to withdraw approval of any prescription combination drugs that do not comply with the 325mg limit. The FDA first requested the limit in 2011, asking manufacturers to comply by this month, but not all of the drug makers agreed, and some drugs with higher levels of acetaminophen are still on the market. Acetaminophen is more dangerous than you might think, killing 150 people per year and sometimes causing rare skin diseases. (Read more acetaminophen stories.)