Double [Dosage] is the Trouble

Avoid acetaminophen toxicity and unintentional overdose.

Acetaminophen is an effective over-the-counter (OTC) pain and fever reliever sold in Canada by the trade name Tylenol. But it’s also commonly used in cold and flu formulas, can be combined with prescription painkillers such as oxycodones and can even be found in off-the-shelf sleeping pills, all of which consumers may not realize.

The problem?

Duplicating therapies can lead to acetaminophen toxicity and unintentional overdose, says Nardine Nakhla. A professor of pharmacy at the University of Toronto and Western University, Nakhla is also a spokesperson for, a site launched last fall by the makers of Tylenol. She says Health Canada has been pushing for such initiatives.

“They realize that, based on many studies conducted, people were not looking at labels when purchasing over-the-counter items because they automatically deem them safe.”

For Nakhla, the site’s most important tool is the product search: users enter the name of any OTC or prescription drug to see if it contains acetaminophen – there are more than 450 available in Canada that do. The site also includes tips for “responsible pain relief” and for understanding medicine labels as well as facts about acetaminophen’s effect on the liver. The liver can only metabolize so much of the drug at a time, and acute liver failure results from overdose.

Adults should never exceed 4,000 milligrams a day from all sources combined, and for children the recommended dose is based on their weight – 65 milligrams per kilogram per day. Nakhla points out that people with hepatic or liver disease and chronic alcohol drinkers are at increased risk due to compromised liver function. Overdose symptoms include vomiting, nausea, malaise, abdominal pain and diarrhea. And severe acetaminophen toxicity can be fatal if untreated.

When considering more than one acetaminophen product at a time, Nakhla echoes the first tip listed on the site: speak to your physician or pharmacist.

In this case, what you don’t know can hurt you.