Tylenol Dose Lowered, What Taking Too Much Can Do

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Acetaminophen, the active ingredient in Tylenol®, is the most widely used pharmaceutical pain reliever and fever fighter in the United States and around the world. To help ensure Tylenol users do not unintentionally take too much of the medication, the makers of Extra Strength Tylenol® are lowering the maximum daily dose.

What harm can taking too much Tylenol do?

Acetaminophen is a safe medication when it is used as directed. Once you ingest acetaminophen, it is rapidly absorbed from the digestive tract (stomach and small intestine) and mainly metabolized in the liver to nontoxic, water-soluble compounds that are eliminated from the body in urine.

When acetaminophen is taken in excess, or even at the 4,000-mg per day level, it can cause liver damage. Because more than 600 over-the-counter products (e.g., Sudafed® Triple Action™, NyQuil®) and prescription drugs (e.g., Percocet®, Vicodin®) contain acetaminophen, there is the potential for unintentional overdosing when people are using more than one medication containing the ingredient.

Use of acetaminophen can cause an elevation of liver enzymes which suggests damage to the liver. In a study published in the Journal of the American Medical Association, 145 healthy adults were randomized to receive either 4,000 mg of Tylenol or a placebo daily for two weeks.

Between 31 and 44 percent of the subjects in the acetaminophen portion of the study had high levels of alanine transaminase (ALT), a liver enzyme, more than three times the upper limit of normal, while none of the subjects in the placebo group showed this increase.

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ALT is an enzyme that helps with the metabolism of protein, and when the liver is damaged, ALT is released into the bloodstream, resulting in elevated ALT levels. Results of this study indicate that acetaminophen can cause liver damage at 4,000 mg daily. ALT levels returned to normal after the subjects stopped taking acetaminophen.

For some people with certain conditions, ingesting lesser amounts of acetaminophen may cause toxicity. Individuals who are fasting, have malnutrition, a viral illness with dehydration or who are chronic users of alcohol are at greater risk of liver damage.

Although the liver is an organ capable of regenerating itself, this self-healing ability can be seriously compromised by repeated use of acetaminophen. Anyone who uses acetaminophen should also be aware of any other medications they are taking that may contain the drug, limit or avoid use of alcohol, and monitor caffeine intake, as it can boost the risk of liver problems caused by acetaminophen.

In fall 2011, the makers of Extra Strength Tylenol will issue new dosing instructions for the product, changing from 8 pills daily (4,000 mg) to 6 pills daily (3,000 mg), and the dosing will change from 2 pills every 4 to 6 hours to 2 pills every 6 hours. Beginning in 2012, the maximum daily dose will also be reduced for Regular Strength Tylenol and other McNeil Consumer Healthcare products for adults that contain acetaminophen.

McNeil has also launched a new education initiative called Get Relief Responsibly™, providing a website where consumers can learn more about Tylenol and which products contain the drug, how to store medications safely, important information about pain relievers, and more.

SOURCES:
Get Relief Responsibly
McNeil Consumer Healthcare
Watkins PB et al. Journal of the American Medical Association 2006; 296(1): 87-93

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