Accessibility Tools

  • Content scaling 100%
  • Font size 100%
  • Line height 100%
  • Letter spacing 100%

Cannabis & psychosis

  • Share

Quick facts

Quick Facts

Cannabis (marijuana, hashish, weed, dope) is the most commonly used illicit recreational drug in Australia. It’s a depressant psychoactive substance that can cause temporary psychotic symptoms and, in some cases, full psychotic disorders like schizophrenia.

  • Cannabis facts

    • It’s addictive: cannabis contains THC, a highly addictive chemical.
    • It’s common: more than 1 in 10 Australians aged 14+ have used cannabis in the past year
    • It’s very common in people with psychotic disorders: cannabis use is much higher in people living with psychotic disorders than in the general population or even people with other mental illnesses. Up to a quarter of people diagnosed with schizophrenia may also have a cannabis use disorder.
  • Cannabis myths

    • Myth: ‘A little bit is harmless’
    • Reality: Cannabis can cause psychotic symptoms even at low doses.
    • Myth: ‘My mate is fine, so I’ll be fine’
    • Reality: Cannabis affects different people differently. Other people’s use can’t predict your reaction.
    • Myth: ‘Cannabis is the biggest cause of psychosis’
    • Reality: Cannabis use makes you more likely to experience psychosis, but your genetics, early development and life experiences have a much stronger effect on your chances of becoming ill.
  • Can cannabis cause psychosis?

    Here’s what research says about cannabis use and psychosis:

    Cannabis use can cause you to experience psychotic symptoms

    Along with the traditional high, cannabis use can cause paranoia, delusions and hallucinations in people who don’t already have a mental illness, even in small doses.

    Cannabis use can also trigger or worsen psychotic symptoms in people living with an illness like schizophrenia, even when their illness is otherwise stable and responding well to treatment.

    Cannabis can trigger a psychotic illness in susceptible people

    Some things can make it more likely that you will experience a psychotic disorder at some point in your life. These include your genetic make-up, your mother’s health during pregnancy, complications with your birth, child abuse, some kinds of head injury and infection, drug abuse, living in urban areas and experiencing high stress and social disadvantage.

    If you already have a predisposition like this, cannabis use can trigger an illness. It can also cause symptoms to occur far sooner than they would otherwise have done.

    Although anyone can experience psychotic symptoms from cannabis use, it hasn’t been demonstrated yet whether cannabis can cause a psychotic illness in someone who isn’t otherwise susceptible.

  • What about medical marijuana?

    Medical marijuana was made legal in Australia in late 2016. It has a growing range of uses, but it isn’t a proven treatment for psychotic illness.

    If you’re worried about the risk of psychosis in using medical marijuana to treat another condition, talk to your doctor.

  • References

    http://www.aihw.gov.au/alcohol-and-other-drugs/illicit-use-of-drugs/cannabis/

    Schoeler T, Monk A, Sami MB, et al. ‘Continued versus discontinued cannabis use in patients with psychosis: a systematic review and meta-analysis.’ Lancet Psychiatry. 2016;3(3):215-225.

    Johanna Koskinen, Johanna Löhönen, Hannu Koponen, Matti Isohanni, Jouko Miettunen; Rate of Cannabis Use Disorders in Clinical Samples of Patients With Schizophrenia: A Meta-analysis. Schizophr Bull 2010; 36 (6): 1115-1130. doi: 10.1093/schbul/sbp031

    Nunez, L. and M. Gurpegui, ‘Cannabis-induced psychosis: A cross-sectional comparison with acute schizophrenia. Acta Psychiatrica Scandinavica, 2002. 105: p. 173–178.

    Favrat, B., et al., ‘Two cases of “cannabis acute psychosis” following the administration of oral cannabis. BMC Psychiatry, 2005. 5(17)

    D’Souza, D.C., et al., ‘Delta-9-tetrahydrocannabinol effects in schizophrenia: Implications for cognition, psychosis, and addiction’. Biological Psychiatry, 2005. 57: p. 594–608.

    Dean K and Murray RM (2005) ‘Environmental risk factors for psychosis’. Dialogues Clin Neurosci. 7(1): 69-80.

    Veen, N.D., et al., ‘Cannabis use and age at onset of schizophrenia. American Journal of Psychiatry, 2004. 161: p. 501–506.

    McLaren J, Lemon J, Robins L and Mattick RP, Cannabis and mental health: put into context. Commonwealth of Australia, 2008, p.33.

Content last reviewed: 12 May 2017

Latest Discussions on the Forum

If you sometimes struggle to say it out loud, or tell someone in person, you can reach out for support here: SANE’s professionally moderated forums are a safe and anonymous community of support that you can access any time of day or night, and on any device.

Latest discussions on the forums

Lived Experience

For anyone living with a complex mental health issue

Connect with others
Posts are loading...

    Carers

    For anyone who cares about or for someone living with a mental health issue

    Connect with others
    Posts are loading...

      Ways we can support you

      Choose from a range of support services, including counselling, peer support, online groups and events, 24/7 community forums, and online information and resources.

      Icon - Shapes representing 3 people

      Online Forums Community

      Available 24/7. SANE’s online community forums provide a safe, non-judgmental space to share your experiences, seek advice and surround yourself with support.

      Icon - shape of a person wearing headphones with a wrap around microphone

      Talk to a Mental Health Professional

      Available Monday to Friday, 10am - 8pm (AEST/AEDT). SANE’s team of trained staff and volunteers provide free support, information, and resources. Call 1800 187 263. Free Translating and Interpreting Service (TIS) available on 131 450.

      Icon - Hands holding a heart

      Additional guidance and support

      Available Monday to Friday, 10am to 8pm (AEST/AEDT). Work with a dedicated support team to identify your goals and tailor a support plan that's right for you. Choose from a range of supports, incl.  multi-session counselling and peer support.

      Icon - Two chat bubble shapes

      Weekly Online Discussion Groups

      Every Thursday at 7pm (AEST/AEDT). Weekly online discussions, guided by SANE peer support workers and supported by counsellors. New topics each week.

      Icon - Calendar

      Monthly Live Educational Events

      Last Tuesday of every month, at 5:30pm (AEST/AEDT). Topic Tuesday is a live Q&A discussion. Each month a different topic is facilitated by a subject matter expert, a community manager or moderator, and supported by a peer support worker.

      Icon - Document with information symbol

      Information and Resources

      Available 24/7. Access information you can trust on complex mental health issues. SANE factsheets and guides are easy to read and can help you understand what’s happening and what strategies can be helpful.

      Icon - Hand holding hand

      Guidance for supporting someone at risk of suicide

      Available 24/7. A resource that provides information and advice about supporting someone who has attempted, or is at risk of attempting, suicide.

      Get Creative with SANE

      The arts have the power to move, to heal and to help us understand ourselves and each other. SANE Create programs provide an outlet to engage with creative activities.

      Icon - Person shape in front of white board

      Peer Guide training and mentoring

      Receive guidance and support to develop the skills to use your personal mental health experiences as a peer support worker, building confidence and readiness for employment or further education.

      Have questions? Click here to read our FAQs or email us at getsupport@sane.org

      Man with a short beard leaning aginst a wall with his arms folded

      Together we can change lives

      Help us provide free essential mental health support and create brighter futures for people with complex mental health issues. Make a tax deductible donation today.

      Donate

      Stay in touch

      Never miss an important update from SANE.

      Please let us know your first name.
      Please let us know your last name.
      Please let us know your email address.

      Please select at least one newsletter