Original cannabis journalism for Canadians

When cannabis causes harm

A new study explores cases of acute cannabis exposure as reported to a U.S. poison control centre. (Rick Madonik / The Canadian Press files) (CP)

A new study explores cases of acute cannabis exposure as reported to a U.S. poison control centre. (Rick Madonik / The Canadian Press files)

Conventional wisdom among many cannabis lovers is that weed isn't particularly harmful, but cannabis exposure can definitely lead to medical emergencies in some cases, as a new research paper shows.

The paper, "Acute cannabis toxicity," is published in the peer-reviewed scientific journal Clinical Toxicology. Researchers analyzed 16 months of data from a poison control centre that serves Oregon and Alaska, both states where recreational marijuana is legal.

Cases of "acute cannabis exposures" reported to the centre were fairly rare, but they did happen. The poison control centre took 68,433 phone calls during the study period, and less than 0.4 per cent of them (253) met the researchers' criteria for a clear case of acute cannabis exposure.

Patients with acute cannabis exposure showed a variety of clinical symptoms, ranging from central nervous system excitation, such as anxiety or paranoia, to sedation such as impaired consciousness or weakness.

Gastrointestinal symptoms such as nausea or vomiting were also noted in some cases, as were cardiac symptoms including palpitations or chest pain.

The authors found the majority of patients received no treatment, but the worst cases led to significant medical interventions such as intubation or ventilation.

Indeed, eight of the 253 cases were serious enough for the patient to be admitted to an intensive care unit, including a nine-month-old boy who ate his parents' cannabis concentrate and a 55-year-old man who unwittingly gobbled a homemade cannabis-infused dessert bar of unknown potency.

A single patient actually died: a 70-year-old man suffered a fatal heart attack after "intentional inhalational exposure to vaporized liquid concentrate product".

Significantly, about 57 per cent of all the cannabis-related calls to the poison control centre involved edible cannabis (144 cases). Sixty-eight of those cases involved patients younger than 18.

Those findings in particular lend support to the Canadian government's decision to take its time with the legalization of commercially-produced cannabis edibles.

For adults, poison control calls after acute exposure to cannabis edibles often appeared to reflect inadvertent overuses, the authors wrote. That suggests Ottawa's decision to limit the dose of THC in single servings of edibles is wise.

In the troubling cases of edibles exposure that involved kids, the edibles usually belonged to their family members, bolstering the case for edibles packaging to be particularly child-resistant. 

But even the smartest regulations and the most childproof packaging won't completely eliminate the risk of bad outcomes for a minority of cannabis users, especially if those users are children exposed to cannabis unintentionally.

In Canada, cannabis-related emergency room admissions appear to be less common than ER admissions involving other drugs, but that doesn't mean they don't happen. Even though cannabis might be less harmful than other substances, it's certainly not benign.


New on The Leaf

  • Legal cannabis containers can easily be copied. (Nathan Denette / The Canadian Press files) (CP)

    Legal cannabis containers can easily be copied. (Nathan Denette / The Canadian Press files)

    Counterfeit cannabis: How can Canadian weed producers stop fraudsters from ripping off their products?
  • Spray and pray: Herb explains what pesticides can be used on cannabis without breaking the law.
  • Better than prison time: Canada's border agency is developing new fines for travellers who bring minor amounts of cannabis into Canada illegally.

Elsewhere on the Weed Wide Web

  • Cannabis NB stores were forced to lay off about 60 workers across New Brunswick because of lower than expected sales. (Andrew Vaughan / The Canadian Press files)

    Cannabis NB stores were forced to lay off about 60 workers across New Brunswick because of lower than expected sales. (Andrew Vaughan / The Canadian Press files)

    The mystery of the empty shelves: A business professor explores the possible reasons for Canada's ongoing shortage of legal cannabis.
  • Rocking the Rockies: More than a third of all Canada's licensed cannabis stores are currently in Alberta.
  • Missed expectations: New Brunswick's Crown cannabis retailer will significantly miss its internal sales projections.

What Next

Share this article

Sign up to receive The Leaflet newsletter!

Recommended for you

Advertisement