The U.S. Food and Drug Administration (FDA) on Wednesday urged doctors to discontinue prescribing drugs that contain more than 325 milligrams of acetaminophen per tablet or capsule, to reduce the risk of liver injury.

Cases of severe liver injury with acetaminophen have occurred in patients who took more than the prescribed dose in one day; took more than one acetaminophen-containing product at the same time; or drank alcohol while taking acetaminophen products.

According to the FDA, "inadvertent overdose" from prescription drugs containing acetaminophen accounts for nearly half of all cases of acetaminophen-related liver failure in the United States, some of which result in liver transplant or death.

"There are no available data to show that taking more than 325 milligrams of acetaminophen per dosage unit provides additional benefit that outweighs the added risks for liver injury," the FDA said in Wednesday's statement.

"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."

In January 2011, the FDA asked drug manufacturers to limit the amount of acetaminophen to no more than 325 mg in each tablet or capsule in a bid to protect consumers from the risk of severe liver damage.

So far, more than half of these manufacturers have voluntarily complied but some prescription combination drug products containing more than 325 milligrams of acetaminophen per dosage unit remain available, the FDA said.