Health Canada and the makers of Tylenol know how many Canadians die every year from acetaminophen, Canada’s most commonly used painkiller.

But they haven’t told you.

The Star has obtained an internal report from drug manufacturer Johnson & Johnson — never before made public — that found between 2000 and 2011, an average of 68 Canadians died each year because of acetaminophen, the painkiller found in hundreds of products from Tylenol to NyQuil.

The Star also obtained two internal reports from Health Canada on use of the painkiller. Those reports found that nearly half of acetaminophen-related deaths investigated by coroners are “unintentional” — people who overdosed accidentally, perhaps because they combined several products without realizing they all contained acetaminophen.

Acetaminophen is very safe when taken as directed, and more than four billion doses are sold to Canadians annually. But the reports, completed last year, contain troublingstatistics and suggest that Health Canada is dragging its heels on major safety reforms recommended by its own scientific experts, an ongoing Star investigation has found.

The Johnson & Johnson report, marked “confidential” and dated September 2014, was released internally and never shared with Health Canada. It documents 820 deaths associated with acetaminophen overdose between 2000 and 2011. The report also notes there were more than 26,300 acetaminophen-related hospitalizations between 2004 and 2013 — an analysis that does not include British Columbia or Quebec.

These statistics, along with others in the report, were “alarming” to a senior industry insider who spoke to the Star on the condition of anonymity.

“I said, ‘My God, if Health Canada is looking at the same thing, we’re in trouble,’ ” he recalled.

He added that the reports triggered an internal debate about reducing dosages and decreasing package sizes. No such changes have been made.

A spokeswoman for Johnson & Johnson in Canada, Shelley Kohut, said the report’s findings were never shared with Health Canada because they were “consistent” with what the federal government regulator had already found in its own report, which was finalized in January 2014.

She added that McNeil Consumer Healthcare, the Johnson & Johnson division that makes Tylenol and one of several manufacturers of acetaminophen, “has a track record of leadership” and pointed to previous changes to packaging and labelling, as well as efforts to educate consumers, doctors and pharmacists.

Kohut also said McNeil will continue working with Health Canada and other groups to “review and implement risk-mitigation approaches.”

“If a consensus emerges saying additional changes are needed, McNeil will continue to act in the best interest of our consumers in Canada and around the world,” Kohut wrote in an email.

The Health Canada reports obtained by the Star — a study titled “Acetaminophen Special Project” — and its executive summary detail the health regulator’s knowledge of acetaminophen risk.

The full report, written by Health Canada’s experts, was not made public. Instead, Health Canada published a five-page summary on its website in July, noting that an executive summary could be requested. A department spokesman, Sean Upton, says the full report is “available upon request” if people contact Health Canada’s marketed health products directorate.

“What we’re seeing is a pretty consistent pattern with Health Canada in terms of not releasing the information that they have available,” said Dr. Joel Lexchin, a drug safety expert at York University. “Health Canada, in terms of its ability to release information in a timely manner, is not very good. And that’s being polite.”

The full report reveals that the public summary only scratches the surface of what the government regulator has learned.

The summary, for example, says the “number of hospitalizations for unintentional overdoses is rising.”

But the full report shows that rise has been dramatic. “Since 2006,the proportion of acetaminophen overdoses reported as accidental or unintentional has risen from 14 per cent to 21 per cent,” the report states.

“In the same time period, the proportion of liver injuries associated with accidental or unintentional overdose rose from 27 per cent to 45 per cent. The rates of overdoses and liver injuries associated with intentional overdose, however, have remained stable.”

In the internal report, Health Canada’s experts urge the implementation of recommendations including:

reducing the maximum daily dose for acetaminophen to 2.6 grams from 4 grams;

removing the drug from prescription opioid-combination products (such as Tylenol 3, which contains codeine);

requiring a prescription for “high dose” products such as Tylenol Extra Strength; and

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restricting bottle size to 40 pills, a dramatic reduction from the 300-pill bottles currently available.

“Although these strategies require significant changes to the way in which acetaminophen is regulated and marketed in Canada,” the report reads, “they are expected to reduce a meaningful proportion of acetaminophen overdoses, injuries and deaths.”

Health Canada has yet to act on those recommendations. In 2009, and again in July, it announced new rules for acetaminophen labels. But Johnson & Johnson’s report suggests the 2009 changes had no effect on reducing overdoses. In fact, the report shows overdoses slightly increasing every year since.

The health regulator said in July it would launch a public awareness campaign and hold a “technical discussion with stakeholders” this fall to discuss other recommendations, which, as the report reveals, were given to Health Canada 18 months ago.

In an emailed statement, Upton, the Health Canada spokesman, said, “Helping Canadians use acetaminophen safely is a priority.

“The length of time to complete the review was affected by its scope (both prescription and non-prescription acetaminophen products in adults and children) and complexity.”

But drug safety experts say Health Canada’s progress on this issue has been “glacial” and “hard to justify.”

“I think the proposed interventions represent good ideas,” said Dr. David Juurlink, a drug-safety expert with Sunnybrook Health Sciences Centre. “And the more Health Canada talks about them without actually doing anything, the more likely people are to be harmed as a result.”

Six things to know about acetaminophen

1. There are more than 480 products sold in Canada containing acetaminophen, including Tylenol, NyQuil, NeoCitran, Midol and Robitussin Total Cough Cold & Flu, to name a few. The danger comes when people unknowingly “double dip” by combining these products — risky behaviour that can lead to overdose.

2. Teenage girls in Canada have a threefold greater risk of intentionally poisoning themselves with acetaminophen, the “drug of choice for teen overdose,” according to Health Canada’s internal report on overdose of the drug.

3. Some Tylenol products are identical, despite being marketed for different purposes. Tylenol Arthritis Pain, for example, is two regular-strength Tylenols packed into a single pill. Extra Strength Tylenol Back Pain has the exact same ingredients as Extra Strength Tylenol Body Pain Night: 500 milligrams of acetaminophen and 400 milligrams of methocarbamol.

4. The recommended daily dose for adults is 4 grams, but it is unclear whether this is truly a “safe daily dose” for everyone. “The dose threshold for toxicity varies greatly among individuals,” Health Canada says in its report, which cites evidence of people suffering liver injury when taking less than the daily dose. People who are malnourished, alcoholics or those suffering from liver disease might also be more vulnerable to overdose.

5. People are more likely to die from accidental acetaminophen overdoses than intentional ones. According to the Johnson & Johnson study, 26,372 patients were admitted to hospital between 2004 and 2013 for acetaminophen overdose and 431 died. Among the deaths, 3.6 per cent were caused by accidental overdoses versus 0.9 per cent caused by intentional overdose.

6. Across Canada, the Yukon, Northwest Territories and Nunavut have the highest rate of intentional overdoses, according to the Health Canada report. Alberta, on the other hand, has the highest rate of unintentional acetaminophen overdoses.