Regular doses of Tylenol, the widely used painkiller that contains acetaminophen as the active ingredient, may be enough to cause liver damage, according to a study in the Journal of the American Medical Association.
The study involved 106 participants, some of whom took four grams of Tylenol (or eight extra-strength Tylenol tablets) every day for two weeks. One group took Tylenol alone, another group took Tylenol with an opioid painkiller and a third group took placebo pills.
Up to 40 percent of the people taking Tylenol, alone or with the other painkiller, had abnormal test results that signaled liver damage. No such results occurred among the placebo group.
The researchers recommended that people take no more than four grams of Tylenol a day, and no more than two grams daily for heavy drinkers.
Because acetaminophen is widely used in over-the-counter and prescription drugs, overdoses are common as people unknowingly combine medications. Overdoses of acetaminophen are the leading cause of acute liver failure.