Skip to main content

Part of Cannabis and your health

This past summer, a housekeeper arrived in the emergency department of Toronto General Hospital with palpitations and vomiting. The symptoms would make any emergency doctor worry about a heart attack, says Dr. Michael Szabo, a staff emergency physician at University Health Network in Toronto. In this case, it turned out that while cleaning a client’s house, the patient had helped herself to a cookie that contained cannabis oil – enough to get eight people high.

In another case at UHN, paramedics brought in an incoherent man in his 60s from a coffee shop. Blood work and CT scans showed no explanation; his blood sugar wasn’t low and he wasn’t having a stroke. Many hours later he regained consciousness and told doctors he’d eaten a chocolate bar containing cannabis.

These are just two of the cannabis-related cases emergency health professionals in Canada have experienced, and many think they’ll see a lot more when marijuana is legalized for personal use on Wednesday.

Cannabis can be more potent today than it was 20 or 30 years ago, says Ian Culbert of the Canadian Public Health Association. One of the biggest causes of poisoning is that the concentration of the active ingredient in marijuana, tetrahydrocannabinol (THC), can vary widely, from less than 5 per cent to more than 40 per cent. While cannabis plants can be bred to have different concentrations of THC, the bigger concern is the unregulated world of edibles – cookies, chocolates and more – that contain THC oils.

As a result, it can be easy to overdo it.

The number of cannabis-related visits to Ontario emergency rooms increased to 1,370 from 449 between 2013 and 2018, according to the Canadian Institutes of Health Information. In Alberta, the increase was to 832 from 413 over the same period. Every poison control centre in Canada has seen a rise in pediatric exposure to cannabis, according to Dr. Margaret Thompson, an emergency doctor and toxicologist who is president of the Canadian Association of Poison Control Centres.

The Globe and Mail surveyed paramedics, emergency doctors, poison control centres and veterinarians to find out what situations could end up in a marijuana-related emergency, and how they can be avoided.

Edibles overdose

Edibles are the main reason behind spikes in ER visits, UHN’s Szabo says. Because edibles aren’t regulated, it’s hard to know what dose of THC you’re consuming. “You can’t look at the bottle and follow the instructions” says Szabo, who adds that the effects of cannabis may not kick in for two to three hours after consumption, leading impatient people to take more than they can handle.

Open this photo in gallery:

Every poison control centre in Canada has seen a rise in pediatric exposure to cannabis.P_Wei/ISTOCK

Mixing alcohol and cannabis

Dr. David Juurlink, head of the clinical pharmacology and toxicology division at Toronto’s Sunnybrook Health Sciences Centre, says mixing cannabis and alcohol is “a recipe for trouble.” He suggests avoiding using more than 20-per-cent THC in any cannabis product.

If you feel you’ve overdone it, Juurlink recommends lying down and waiting for the sensation to pass, which could take a few hours. “If you feel extremely unwell, it wouldn’t be wrong to seek medical attention, especially if you have other health problems,” he says.

Cyclic vomiting

A common reason to visit the ER after smoking pot is cannabis hyperemesis syndrome, also called cyclic vomiting. Causing continuous vomiting and retching, the syndrome is hard to treat, although it is popularly believed to stop during hot showers.

This year, studies done in both Hamilton and Calgary showed hundreds of suspected cases in a two-year period, but noted the diagnosis is tricky to pin down. A trial is under way in Kingston, at Queen’s University, to see how to shorten the time it takes in the emergency room to care for people vomiting from cannabis use.

Collisions and child endangerment

Paramedics have seen more marijuana-related calls and are concerned about impaired driving causing collisions, as well as children who accidentally consume cannabis edibles, says Randy Mellow, president of Paramedic Chiefs of Canada. He says both scenarios have already happened a few times this year, although paramedics don’t expect it to make a big difference in the volume of 911 responses. “Don’t drive while you’re drunk, and don’t drive while you’re high,” Mellow says.

While most people who present for help will know they’ve consumed a product containing THC, children who accidentally consume marijuana might not. Parachute Canada, a charity focused on reducing preventable harm in children, teamed up with Canada’s poison control centres to raise awareness of children and cannabis, which it says is “a serious public-health concern.”

A lack of regulations for child-resistant packaging is partly to blame, Parachute says, for an increase in pediatric poisonings called in to poison control lines in Manitoba, Nunavut and Ontario, where a 50-per-cent increase was seen over five years, to 234 cases from 116. Parachute recommends treating cannabis like any other medication or household toxin: Keep it locked up and out of reach of children.

Teens are also a group to watch. In Colorado, which legalized medical marijuana in 2010 and recreational marijuana in 2014, surveys show that only 7 per cent of teens used marijuana in 2015, the same rate as before it was legal; but cannabis-related emergency-room visits by adolescents quadrupled to 639 between 2009 and 2014, meaning five of every 1,000 emergency visits were associated with marijuana. The number of children under the age of 10 with unintentional cannabis poisoning went from one in 2009 to 16 in 2015.

Finally, an August study in the journal Pediatrics found THC in human breast milk at significant concentrations; other studies have shown that THC is found in the stool of breastfeeding infants whose mothers consume cannabis, suggesting babies metabolize THC, which has been shown to delay psychomotor development. Breastfeeding mothers should refrain from using cannabis.

Pet emergencies

A wave of unintentional overdoses is expected in pets, too. In the United States, a veterinary poison control line saw a 448-per-cent increase in marijuana-related poisonings over the past six years, and dogs whose owners have medical marijuana licences were more likely to present to an animal hospital poisoned, in a study of vet clinics in states with medical marijuana. In that study, two dogs died after eating edibles containing THC.

“Dogs have a much stronger sense of smell. They’ll find your stash, so make sure it’s completely inaccessible to them” Toronto veterinarian Dr. Joanne Cockshutt says. She recommends a storage container that dogs won’t be able to chew into or break.

Signs your dog may be marijuana-poisoned include stumbling, drooling and loss of bladder control. “Many people bring us their dogs thinking they’ve had a stroke, but it’s marijuana.”

Blair Bigham is an emergency-medicine resident at McMaster University in Hamilton.

Your Globe

Build your personal news feed

Follow topics related to this article:

Check Following for new articles

Interact with The Globe