The legalization of cannabis in Canada has not been a total public health “disaster,” but it has not been “a comprehensive or unequivocal success” either, a study in the Canadian Medical Association Journal has concluded.

The report does find that social justice outcomes from legalization have been generally positive, however. The report was released just before the fifth anniversary of legalization.

“At this stage, cannabis legalization in Canada appears not to have been the public health disaster anticipated by some of its opponents, but it cannot be described as a comprehensive or unequivocal success for public health either,” the report’s authors say.

Among the findings, the authors observed a 20 per cent increase in the number of emergency department visits among youth in Ontario and Alberta for cannabis-related disorders and poisonings.

A 21-year-old fourth-year biology student at the University of Victoria, who asked to remain anonymous, said she was diagnosed with cannabis-induced psychosis after visiting an emergency room at a Victoria hospital in September. 

She said she had used cannabis frequently throughout the summer, partly as a means to cope with the death of a close friend.

She said she had never suffered from a severe negative reaction to cannabis before the incident that sent her to an emergency room.

On this occasion, the student says she began to feel nauseous and light-headed after smoking a joint with some friends.

“Repeatedly I was thinking to myself, ‘I’m hearing everything all at once, everything all at once.’ … It was really scary and I’ve never had that happen before.”

User describes experiencing cannabis-induced psychosis

These relatively mild symptoms soon turned into auditory hallucinations and extreme paranoia, which spiralled, prompting a sober friend to take her to the hospital. 

“Repeatedly I was thinking to myself, ‘I’m hearing everything all at once, everything all at once.’ … It was really scary and I’ve never had that happen before,” the student said.

She said a lack of education about the phenomenon made the situation much more frightening than it might have been otherwise.

“There was one point where I (thought) it’s a panic attack or something, because nobody talks about cannabis-induced psychosis and how scary it is, and nobody really explains it, so I was really confused as to what was happening.”

She was admitted to hospital, but after having her blood taken and vital signs checked, she was discharged.

She said that although the experience was very frightening, her biggest worry was developing long-term effects such as schizophrenia or chronic nausea. As a result she has stopped using cannabis.

In addition to being extremely unpredictable, cannabis-induced psychosis can be difficult to recognize and treat. 

Dr. Jill Wiwcharuk, who works at the Cool Aid Community Health Centre and in the emergency room at Saanich Peninsula Hospital in Victoria, says it is important to distinguish between uncomfortable intoxication and psychosis. Wiwcharuk has spent much of her career working with people who use substances and are suffering from addiction.

“If you’re intoxicated or having an overdose, you just reassure people. You might give them an IV with some fluids if they are vomiting a lot and they’re dehydrated and you just try to keep the stimulation down, turn the lights down and just reassure them that they’re gonna be feeling better soon,” said Wiwcharuk.

“Psychosis is entirely different. So then, someone’s coming in and they don’t have to have had an overdose at all. Sometimes cannabis induced psychosis can last well after the acute period of intoxication.”

Differences in negative reactions to cannabis use


Cannabis-Induced Psychosis:

Psychotic symptoms such as hallucinations, delusions, dissociations, etc. caused by chronic use of and/or cannabis withdrawal.


Cannabis Overdose:

Immediate symptoms such as nausea, vomiting, paranoia, etc. caused by overuse of cannabis.


Cannabinoid Hyperemesis Syndrome:

Long-lasting symptoms such as chronic vomiting, nausea and stomach pain caused by chronic, usually daily use of cannabis.


Click here for more information on Cannabis-Induced Psychosis, Cannabis Overdose and Cannabinoid Hyperemesis Syndrome.

Wiwcharuk says there is a lack of education around cannabis consumption, but she believes legalization has led to safer substances and less stigma for users, which can encourage people to get themselves help in crucial moments and may ultimately be the difference between life and death.

“I think legalization was a good thing. Certainly there’s challenges and risks associated with legalization, but there’s challenges and risks associated with prohibition. So, it’s never going to be a perfect world, but I think legalization definitely resulted in net positive changes,” Patterson said.

Dr. Romina Mizrahi, a psychiatrist and professor at McGill University with two decades studying the effects of cannabis on the brain in young people, echoed the need for wider access to information about the effects of cannabis on users.

“There’s been a little bit of education on this, although it’s not sufficient. I think because the harms associated with cannabis use are only more recently being investigated and known. Before it wasn’t really very much known. So, it takes time for the research to catch up with public policy,” Mizrahi said. 

“Previously, lots of people (who were in possession of cannabis), particularly underrepresented people, were stopped by police and they had to deal with the criminal system. None of that is happening now, which is good because then our police officers can actually take care of other matters, which are important. This is a social justice benefit of the legalization of cannabis.”

Dr. Romina Mizrahi, a psychiatrist and professor at McGill University

Mizrahi also mentioned that it is important to consider the benefits of legalization in areas other than public health, such as social justice in Canada.

“Previously, lots of people (who were in possession of cannabis), particularly underrepresented people, were stopped by police and they had to deal with the criminal system. None of that is happening now, which is good because then our police officers can actually take care of other matters, which are important. This is a social justice benefit of the legalization of cannabis.”

Dr. Zachary Patterson, a neuroscience professor and researcher at Carleton University agrees that although most Canadians do not understand the potential harms associated with cannabis use, it is important to acknowledge the positive outcomes of legalization including the fact that cannabis and its effects are now easier to study.

“Cannabis legalization certainly made research more accessible, since we’re no longer dealing with a scheduled, controlled substance. So it opened the doors in terms of access for research purposes, which I think is good.”

“I have many patients who use substances. And I see how people that use substances are often so stigmatized when they walk into a hospital or a clinic, yet mind altering substances have been around since the beginning of time,” said Wiwcharuk.

“They’re using a substance for the purpose of euphoria, and feeling good is not a new concept. And whenever we try to make it illegal or something, it doesn’t work. There’s more and more harm that happens to people because of violence around a black market essentially.”