Tylenol's an effective pain reliever and fever reducer, but take too much and you can damage your liver. Acetaminophen overdoses account for half the U.S. cases of acute liver failure. “Once it reaches a certain point, it’s over. Your liver is destroyed,” says Dr. Russell Robertson of Northwestern University’s Feinberg School of Medicine.
Take no more than 4,000 milligrams of acetaminophen a day (8 extra-strength Tylenol capsules). Other drugs, like multi-symptom cold medications, may also contain acetaminophen so check labels to make sure you’re not unwittingly consuming too much. And don't take Tylenol to prevent or cure hangovers: alcohol and acetaminophen require the liver to work too hard by competing for the same “breakdown pathways,” says Robertson. Try water instead.