FDA advisors warn: high doses of acetaminophen cause liver damage

July 1, 9:06 PMDetroit Health and Beauty ExaminerSherri Dansby

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The Advisory Committee of the U.S. Food and Drug Administration (FDA) met June 29 and 30, 2009 to discuss the risks to consumers for liver damage due to overdosing on the drug acetaminophen, one of the most commonly used active ingredients in medicines to relieve pain and fevers. Most people know that it’s in over-the-counter (OTC) drugs, like Tylenol and Excedrin, but it’s also in prescription drugs. 

On July 1, 2009, the Advisory Committee voted to recommend that the FDA take prescription drugs that contain narcotics and acetaminophen, such as Vicodin and Percocet, off the market. The advisors cited the high risk for consumers to exceed safe amounts of acetaminophen when prescription narcotics containing this ingredient and OTC acetaminophen drugs are taken together.

The advisors also voted to recommend that the FDA lower the maximum 24 hour dosage of acetaminophen in OTC and prescription drugs, as well as review the dosing limits for children. While the FDA does not have to take the advice of the Advisory Committee, it generally does and changes to rules regarding acetaminophen are likely to happen within six months of the July vote.

The FDA emphasizes that acetaminophen is generally safe when taken as directed currently and has been proven effective as a pain reliever and fever reducer. But acetaminophen can also cause liver damage when taken in excess of current recommended dosages. Nearly 500 deaths are attributed to an acetaminophen overdose each year.

A study of 22 specialty centers across the United States showed that an overdose of acetaminophen was the leading cause of acute liver failure for the years 1998 through 2003 and a 2007 study had similar findings. The FDA’s Advisory Committee warns that consumers may inadvertently take more acetaminophen than is safely recommended because of its widespread use in many drugs.

Acetaminophen is used in combinations of other active drug ingredients, such as in OTC and prescription medicines used to relieve symptoms of colds, flu, allergies and sleeplessness, such as NyQuil, Allerest and other popular medications. 

The FDA cautions:
“You may not notice the signs and symptoms of liver damage right away because they take time to appear. Or, you may mistake early symptoms of liver damage (for example, loss of appetite, nausea, and vomiting) for something else, like the flu. Liver damage can develop into liver failure or death over several days.”

“The mechanism of liver injury is not related to acetaminophen itself, but to the production of a toxic metabolite. The toxic metabolite binds with liver proteins, which cause cellular injury. The ability of the liver to remove this metabolite before it binds to liver protein influences the extent of liver injury.”

Consumers should read the “Drug Facts” and “Directions” on OTC drugs and the detailed information provided with prescription medications, to check active ingredients for acetaminophen, or “APAP” on prescriptions. Consumers should check this information for the proper dosing instructions and the maximum amount to take within 24 hours. To lower the risk of liver damage associated with acetaminophen, the FDA recommends:

• Follow dosing directions and never take more than directed; even a small amount more than directed can cause liver damage.
• Don’t take acetaminophen for more days than directed.
• Don’t take more than one medicine that contains acetaminophen at a time. For example, your risk of liver damage goes up if you take a medicine that contains acetaminophen to treat a headache, and while that medicine is still working in your body, you take another medicine that contains acetaminophen to treat a cold.
• If you drink alcohol or have liver disease, taking acetaminophen puts you at greater risk of getting liver damage, even when taking acetaminophen at the recommended dose.
• If you take the blood thinner warfarin, you should also talk to your doctor before taking acetaminophen because taking warfarin and acetaminophen together may raise your risk of bleeding.

For more information about acetaminophen, talk to a doctor, nurse, or pharmacist, or visit the FDA’s consumer web pages:

Acetaminophen and Liver Injury: Consumer Q & A
Don’t Overdo It with Acetaminophen (video)
Safe Use of Over-the-Counter Pain Relievers and Fever Reducers
A Guide to Safe Use of Pain Medicine

Contact the FDA at 1-888-INFO-FDA, or e-mail questions to the FDA at druginfo@fda.hhs.gov.