If they continue this for four or five days, they could potentially suffer from a “staggered overdose” and the risk of liver injury becomes very real, said Karvellas. He estimates that roughly half of the acute liver failure cases he sees caused by acetaminophen are “therapeutic misadventures” - and about half of those people double dipped.

Staggered overdoses are dangerous because people don’t realize they are overdosing and are slower to seek treatment. Studies have shown that people who overdose accidentally are more likely to die than those who attempt suicide by swallowing up to twice as much acetaminophen.

People may also double dip with prescription opioids that contain acetaminophen, such as Percocet. Of the 107 accidental deaths in the Statistics Canada’s coroners database, roughly 14 were linked to opioid combination products.

“These substances are habit forming,” explains Sunnybrook’s Juurlink. “(If) someone has a habit and they’re taking 20 tablets of Percocet a day - they’re taking a lot of acetaminophen with that too.” (Twenty Percocets would contain the same amount of acetaminophen as 20 regular-strength Tylenols.)

And then there are people like Ashley Campbell - young people, often women, who take too much acetaminophen on an impulse without necessarily wanting to kill themselves.

“It’s particularly tragic when they show up two days later and they’ve missed the window of treatment with the antidote,” said Dr. Marco Sivilotti, an associate professor with Queen’s University who is studying acetaminophen overdoses. “They reach for acetaminophen primarily because it’s readily available.”

Marotta at London Health Sciences Centre says his hospital has seen an uptick in accidental acetaminophen overdoses recently - but he questions how this problem should be addressed.

“In the scheme of things, this is a tiny problem,” Marotta said. “To get a huge public awareness out there about perfect dosing of Tylenol - the cost and the ability to do that, and the bang you would get for your buck - is probably not what our society wants to spend our money on when you’ve got major public health issues out there already like alcohol and smoking.”

Juurlink echoes a concern raised in Health Canada’s 2009 report - by restricting access to acetaminophen, consumers will turn to alternatives like aspirin and ibuprofen, which can be damaging even at recommended doses.

“Those drugs have their own side effects and I would say they are much more likely to cause harm than acetaminophen,” Juurlink said. “So the alternatives are almost certainly worse, even when taken as directed, than acetaminophen.”

It is difficult to compare acetaminophen overdose deaths with those caused by ibuprofen or aspirin, Juurlink said - the latter may cause heart failure or stomach bleeding, more common issues that doctors may not recognize as being drug induced.

For Juurlink, the bigger problem is society’s attitude that “for every problem there is a pill.” The real message, he said, should be for people to take fewer drugs overall.

But he agrees that more should be done to tackle purely accidental overdoses from acetaminophen.

“It’s people who weren’t trying to hurt themselves, they were just doing something they thought was totally safe,” he said. “The real question is: What can we do to prevent that from happening?”

###

For Dr. Joel Lexchin, a York University professor and one of Canada’s leading drug experts, health regulators should have a lower risk threshold when it comes to something as widely available as acetaminophen.

“This particular product is widely available in large quantities without a prescription - so that puts it in a somewhat different class,” Lexchin said. “Some of the cancer drugs are extremely toxic. But, on the other hand, you can’t walk into a drugstore and buy them just because you want them.”

He points out that Health Canada has taken more drastic action on drugs associated with far fewer deaths than acetaminophen. For several months in 2005, Health Canada suspended market authorization for Adderall XR, a treatment for attention deficit hyperactivity disorder, after it was linked with a dozen pediatric deaths in the U.S.