The Tylenol Scare

For many of us suffering occasional aches and pains, reaching for the Tylenol has become almost a reflex. The best-selling over-the-counter pain reliever and its generic copycats are staples in American medicine cabinets. The active ingredient in Tylenol is acetaminophen, a versatile molecule that can cool a fever, soothe a teething baby and dull the sharp joint pains of osteoarthritis.

Now, however, the U.S. Food and Drug Administration is asking some tough questions about acetaminophen. It's a drug that can do serious damage to the liver when used outside prescribed guidelines, and it's not at all clear that the warnings on the label are being heeded--or even read--by consumers.

The FDA's scrutiny was triggered by an eye-opening report by the University of Texas Southwestern Medical Center, where researchers tracked more than 300 cases of acute liver failure at 22 hospitals. A team led by Dr. William Lee found that 38% of these liver failures were associated with excessive acetaminophen use. In a second study, Lee tracked 307 adults suffering from severe liver injury (but not full-fledged failure) at six hospitals. Once again, acetaminophen was linked to as many as 35% of the cases, most of them preventable.

"The fact that acetaminophen in large doses can damage the liver is nothing new," says Lee. "What we found surprising, however, was how unaware people were of the dangers of ingesting too much."

Tylenol's manufacturer, for its part, insists that acetaminophen is safe if used properly. "But as part of an ongoing process, we are constantly talking to the FDA about how we can improve the label," says Dr. Anthony Temple, a vice president of McNeil Consumer Healthcare.

Most people seem to assume that there's no such thing as overdosing on an over-the-counter pill; if one dose doesn't take the sting from their pain, they simply pop another. But you can't gobble acetaminophen tablets like so many M&Ms.; The drug produces toxic byproducts that are funneled to the liver--which ends up working overtime to clear them out of the body. If you ingest too much acetaminophen, toxins can build up in the bloodstream and do serious damage.

People with a history of liver disease such as cirrhosis or hepatitis C should always consult their physician before taking acetaminophen-based medicines. A common mistake is to mix alcohol with acetaminophen; alcohol impairs the liver's ability to clear toxins from the blood and can easily lead to an overdose.

You also have to pay careful attention to the ingredients in cold and flu remedies. Many contain acetaminophen, which means you need to add up the doses to make sure that you are consuming no more than the suggested daily maximum of 4 grams for adults. Most reported cases of acetaminophen toxicity have been in people who consumed two to three times the suggested dose in a 24-to 48-hour period.

If one type of pain reliever isn't working, you can try a different one--say, aspirin or ibuprofen--but you should know that each of them has its own problems (including upset stomach and ulcers). Whatever you take, make sure you read the instructions.

Dr. Ian is a medical correspondent for NBC's Today show. E-mail: ianmedical@aol.com .