Acetaminophen over-use can lead to serious liver damage

By Dr. Ananya Mandal, MDNov 24 2011

Common pain and fever Acetaminophen (best known by the brand name Tylenol) taken over a long time can cause liver failure and death, according to a new study.

These "staggered overdoses" can occur when people have ongoing pain and repeatedly take a little more acetaminophen than they should, explained Dr. Kenneth Simpson, of the University of Edinburgh in Scotland, author of the study, published Nov. 22 in the British Journal of Clinical Pharmacology.

“They haven't taken the sort of single-moment, one-off massive overdoses taken by people who try to commit suicide, but over time the damage builds up, and the effect can be fatal,” Simpson said in a journal news release.

The researchers analyzed data from 663 patients with acetaminophen-induced liver injury who were admitted to the Royal Infirmary of Edinburgh, Scotland between 1992 and 2008. Of those patients, 161 had suffered a staggered overdose while taking acetaminophen to relieve a variety of ailments, such as headache, toothache and abdominal and muscular pain.

They found that compared with people who'd taken a single overdose of acetaminophen, those with a staggered overdose were more likely to have liver and brain problems, require kidney dialysis or help with breathing, and were at greater risk of dying.

Those who ingested more than 4,000 mg of acetaminophen in a single day spread out over more than one time point had a significantly higher mortality rate compared with those who overdosed at a single time point (37.3% versus 27.8%), according to Simpson.

Additionally the researchers warn that patients with a staggered overdose may not report that they've suffered an overdose when they come to the hospital. They may just report feeling unwell. Doctors need to recognize and treat this situation quickly, Simpson said. “Staggered overdoses or patients presenting late after an overdose need to be closely monitored and considered for the (acetaminophen) antidote, N-acetylcysteine, irrespective of the concentration of (acetaminophen) in their blood,” he said in the release.

Acetaminophen is one of the most commonly used drugs in the world, with 28 billion doses purchased in the U.S. in 2005 alone. Tylenol overdose is the leading cause of acute liver failure in the U.S., leading to 26,000 hospitalizations and nearly 500 deaths annually, according to the Food and Drug Administration (FDA).