To prevent overdoses, the Food and Drug Administration (FDA) has issued strict new limits on a common ingredient in prescription painkillers, The New York Times reported Jan. 14. 

The FDA has ruled that prescription painkillers may contain only 325 milligrams of acetaminophen — about half of what many contain today.

Acetaminophen is a very popular ingredient in prescription pain medication and is also available over-the-counter in products such as Tylenol. Some patients increase their risk of overdose by supplementing prescription pain pills such as Percocet or Vicodin — which contain narcotics combined with acetaminophen — with an over-the-counter drug that contains acetaminophen, the agency said.

Overdoses, which can cause severe liver damage, kill over 400 people and hospitalize another 42,000 in the United States every year.

Drug-makers will have three years in which to adjust their formulas or take their products off the market. They will also have to add more explicit warnings about overdose risks to their packaging.

“F.D.A. is taking this action to make prescription combination pain medications containing acetaminophen safer for patients to use,” said Dr. Sandra Kweder, deputy director of the FDA's Office of New Drugs. 

In 2009, an advisory panel recommended that the FDA outlaw acetaminophen as an ingredient in prescription painkillers. The FDA chose a more moderate course by limiting the allowable amount of acetaminophen in such pills. 

“We don't believe we're making these products less effective,” Kweder said. “The amount of acetaminophen in these products has gradually crept up over the years.”

The agency's ruling will affect a lot of patients and pills. Over 200 million prescriptions are written each year in America for painkillers that combine opioids like codeine, oxycodone, or hydrocodone with acetaminophen.

About half of acetaminophen overdoses are caused by prescription pills. Many overdoses are the result of over-the-counter medications. Once the FDA's new ruling takes effect, the acetaminophen content in some products, such as like Extra-Strength Tylenol, could exceed that found in prescription drugs.

The New York Times said that limiting acetaminophen in over-the-counter medications would be a “far more time-consuming and burdensome regulatory process” for the agency, and the FDA has not decided whether to act.

“We have not made a decision about what action or actions to take with regard to over-the-counter products,” said Dr. Kweder. “We're continuing to consider our options along that line.”