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Alcohol & Other Drugs

Cannabis and Schizophrenia


How can I support someone who has schizophrenia and is using cannabis?

Authors: BC Schizophrenia Society and Canadian Institute for Substance Use Research


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If someone in your life has schizophrenia or other serious mental health issues and is using cannabis, you may struggle to understand how you can help. While it is legal for people aged 19 and older to use cannabis in BC, as with alcohol, cannabis use may have both negative and positive effects. This is particularly true for people with factors predisposing them to serious mental health issues.

About schizophrenia

Schizophrenia affects about 1% of the population and is not uncommon. If you have a father, mother, brother or sister with schizophrenia, your chance of developing schizophrenia increases to 10%.

Understanding schizophrenia

Schizophrenia is a neurological disorder that most often strikes young people in their prime, with symptoms first appearing between the ages of 16 to 25. It distorts a person's senses and impairs their reasoning and understanding of the world, sometimes making it difficult to tell what is real from what is not real. When a person first experiences symptoms of schizophrenia, it can be extremely frightening.

Those living with schizophrenia may experience hallucinations (sensory experiences created by your mind, but that are not real), delusions (firm false beliefs that are not rooted in reality) and paranoia (thinking or feeling that you are being threatened by someone or something)—all of which are symptoms of psychosis.

Psychosis and schizophrenia are often misunderstood as a result of sensational media stories and popular misinformation. Psychosis is a condition in which people lose touch with reality. Causes of psychosis include various mental health disorders, medical conditions or substance use. Schizophrenia is a mental health disorder that often includes periods of psychosis. In addition to symptoms of psychosis, people living with schizophrenia may also experience flattened emotional responses, disordered thinking, poor memory and may have difficulties in daily living.

Schizophrenia affects about 1% of the population and is not uncommon. If you have a father, mother, brother or sister with schizophrenia, your chance of developing schizophrenia increases to 10%. Schizophrenia is not caused by poor parenting, lack of education, poverty or personal failures of an individual. Schizophrenia is treatable and its symptoms can be successfully managed through the use of medication and, for some people, life skills training and support.

Understanding substance use

People have been using cannabis and other drugs like alcohol and tobacco throughout history. People use these drugs, to feel good, feel better, do better or explore new experiences. We might think of them as tools people use to achieve certain goals. Like all tools, drugs may help us in particular ways. But when not used carefully, they can also harm us or other people around us.

When people use drugs, they are manipulating the pleasure and reward system in their brains to achieve some perceived benefit. Our brains are wired to associate life-sustaining activities—eating, sleeping, sex—with pleasure or reward. Drugs tap into that wiring and modify our feelings of pleasure, as well as our movements, emotions, thinking and motivation.

While low to moderate cannabis use has less potential for harm, prolonged or heavy use is associated with significant harm. Such use is often a way to cope with stress or deal with unpleasant feelings but can lead to less thought about potential harms and little consideration of alternatives for coping such as talking with a friend or engaging in physical activity.

Cannabis has been associated with an increased risk for psychosis and schizophrenia for people with factors predisposing them to serious and persistent mental health issues (particularly those with a family history of severe mental illness). Some people who use large amounts of cannabis even without such risk factors may experience a psychotic episode. These episodes usually resolve relatively quickly. But for some people, the episode may trigger further episodes that can later contribute to a diagnosis of schizophrenia or other persistent mental illness.

How you can help

As a parent, caring adult, or friend, an open respectful relationship with the person you care about is one of the best ways to help and prevent harm. Letting the person know they can approach you at any time to talk about cannabis, mental health issues or anything else says they matter to you, and you are ready to listen. This helps them realize that they are not alone.

Recognize that the person may be using cannabis as a tool to deal with symptoms related to their schizophrenia. This will help you engage in dialogue that explores the person's own experiences rather than focusing on the drug use itself. This way the person can reflect on the reasons for their drug use, its impact on their life and other tools that may be available.

Be curious, avoid confrontation or giving unwanted advice, and be honest in sharing your own experiences, feelings and concerns. This is best achieved when we openly seek to understand the other. Ask open questions that avoid judgements and encourage reflection. And listen, listen, listen.

You too are not alone. Reaching out and getting support for yourself can be a key aspect of increasing health and well-being for you and the person you care about. Below are links to some resources and services for you, and that can help you to support someone you care about who has serious mental health concerns and is using cannabis.

Information resources

Support resources

  • BC 211 connects you to a range of programs and services, including substance use supports, in your community

  • Helplines for Youth in BC. If you or someone you know is in crisis, you can call: 604-872-3311 in the Greater Vancouver area, or 310-1234 from anywhere else in the province.


  • Fischer, B., Russell, C., Sabioni, P., van den Brink, W., Le Foll, B., Hall, W., Rehm, J., & Room, R. (2017). Lower-Risk Cannabis Use Guidelines: A comprehensive update of evidence and recommendations. Public Health Policy, 107 (8), p. e1-12.

  • Hamilton, I. (2017). Cannabis, psychosis and schizophrenia: Unravelling a complex interaction. Addiction, 112, p. 1653–1657.

  • Ksir, C., Hart, C. (2016). Cannabis and Psychosis: A critical overview of the relationship. Current Psychiatry Reports, 18(12), p. 1-11.


About the author

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The BC Schizophrenia Society helps individuals and families find their way in the mental health system. They also provide regional programs and services to help people with serious mental illnesses and their families. For more, visit or call 1-888-888-0029.

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The Canadian Institute for Substance Use Research, formerly CARBC, is a member of the BC Partners for Mental Health and Substance Use Information. The institute is dedicated to the study of substance use in support of community-wide efforts aimed at providing all people with access to healthier lives, whether using substances or not. For more, visit


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