What’s the link between cannabis & schizophrenia & should you be worried?

Studies have shown that schizophrenia only affects up to 1% of the general population, but if you use cannabis, your chances of suffering from schizophrenia can increase by as much as 7X. Why is that?

What is schizophrenia?

First, we should take a look at what schizophrenia is- a mental illness with symptoms that include abnormal behaviour and even losing touch with reality, that often manifests as hallucinations (such as seeing or hearing things), delusions, and lack of motivation.

People with schizophrenia often have other mental health issues as well, such as anxiety or depression.

Who’s at risk?

There are many factors involved for cannabis-related mental health issues such as your age when you first started using cannabis, how much and how often you use (or used) it, and whether your family has a history of mental illness.

Also, if you’ve ever had a bad trip on cannabis, that means you could be at high risk of a psychotic disorder, according to the Schizophrenia Society of Canada, and unfortunately, there is no way of testing if you’re at risk of cannabis-related psychosis.


The jury is still out on whether cannabis can cause mental illnesses like schizophrenia or simply triggers it in people who are already at higher risk. We also don’t know if people at higher risk of schizophrenia are more likely to use cannabis in the first place- the only thing that scientists know so far is that there is a correlation between cannabis use and schizophrenia, however small it may be.

It is generally understood that cannabis use is more likely to have harmful effects on adolescents whose brains have not yet fully developed, and that’s why some politicians pushed for having the minimum age to purchase recreational cannabis 25 years old. But that didn’t end up actually happening, as most provinces are setting the age at either 18 or 19, which brings the legal age for cannabis in line with their drinking laws.

Cannabis-related emergency room visits increase 300%

The Toronto Star found that in 2017, there were 567 patients admitted to emergency rooms for mental health issues related to cannabis in four BC hospitals- a 300% increase since 2012.

But that increase might be due to more people trying cannabis and being more willing to admit to cannabis use as the stigma around it fades, or the fact that doctors are looking for cannabis-related symptoms more than ever as recreational use of the plant becomes more accepted by mainstream society.

Cannabis has also gotten significantly stronger in the past few decades. The “hippie weed” smoked in the 60s and 70s had very low THC levels, around 1-5%, compared to the modern day green that has THC levels that range from 15-30%, with some as high as 50%!

There are also so many different ways to use cannabis now- from the tried-and-true joints, bongs, and pipes from yesteryear to the assortment of high-potency concentrates like BHO (aka butane hash oil that comes in many forms like shatter, budder, and wax) that use state-of-the-art extraction methods.

Dr. Bonnie Henry, B.C.’s provincial health officer, reminded us to keep the big picture in mind, telling the Toronto Star:

“[A] 300 percent increase is still quite small in the actual numbers. These are dramatic but not common events.”


Much the same way that alcohol isn’t for everybody, it’s the same thing for cannabis. Not everybody enjoys or responds well to it.

Like with anything, if it’s your first time using cannabis, start low and go slow. Don’t bite off more than you can chew (especially if it’s an edible!) and take the time to feel out how your body and mind react to cannabis.

It’s important to keep in mind that cannabis is not a panacea that will solve all of society’s ills, although this author personally believes that cannabis does a lot more good than harm, and can be especially effective in harm-reduction programs as a substitute for harder drugs.

And while there you can bet in the next few years will be new studies and articles talking about the benefits and harms of cannabis, it’s important to take everything with a grain of salt. Even in the face of scary-sounding numbers like a 300% increase in cannabis-related emergency visits or how cannabis can increase your risk of schizophrenia by 7X, your risks of suffering from schizophrenia are still very small.

And lastly, remember that no matter what anybody tells you, correlation does NOT imply causation because when it comes to cannabis and mental health, it is not as simple as cause-and-effect.


Featured image courtesy of Everyday Health.


Cannabis and Psychosis: Explore the Link.

CBC: Marijuana use down among minors, up among older Canadians, StatsCan study finds.

Nursing Times: ‘Skunk’ cannabis raises psychosis risk seven-fold.

Toronto Star: Bad trip from smoking pot? It could be a sign of mental illness.