Cannabis for Medical Purposes

Last revised: August 2, 2023

Ottawa Public Health provides information on the health effects from using cannabis so residents can make informed decisions that are best for them. Ottawa Public Health recommends that anyone who is considering the use of cannabis for medical purposes talk with a health care provider.

Prescription cannabinoids (nabilone and nabiximols) are approved therapeutic drugs in Canada. Dried and fresh cannabis and cannabis oil are not approved as therapeutic drugs by Health Canada as current research does not establish their safety and effectiveness. 

The evidence on cannabis for medical purposes continues to emerge. Some research shows that the CBD (cannabidiol) found in cannabis may help treat specific medical conditions. The College of Family Physicians of Canada has published a Simplified guideline for prescribing medical cannabinoids in primary care. A summary of the findings and guidelines is available. Recommendations include limiting medical cannabinoid use in general, but also outline potential restricted use in a small subset of medical conditions for which there is some evidence (neuropathic pain, palliative and end-of-life pain, chemotherapy-induced nausea and vomiting, and spasticity due to multiple sclerosis or spinal cord injury).

Concurrent Disorders – Mental Health and Cannabis Use

  • Mental illness and problems occurring with substance use often occur at the same time. Having one can increase the risk of developing the other.
  • Using cannabis can increase the risk of experiencing psychosis and schizophrenia, especially if your client is a teenager, uses every day or almost every day, or someone in their family has or had these conditions.
  • Some perons with mental illness report using cannabis to help cope with their symptoms. Cannabis can increase the presence of symptoms, especially for those with psychosis.
  • If your patient or someone in their family has a history of psychosis or problems occurring with substance use, it is best for them to avoid using cannabis. If a patient requires help to manage their stress, these online resources may be helpful.

Lower-Risk Cannabis Use Guidelines (LRCUG)

The Lower-Risk Cannabis Use Guidelines (LRCUG) are an evidence-based tool that allows persons who use cannabis to modify and reduce their risks for health harms associated with cannabis use based on evidence-informed recommendations. The scientific version of the LRCUG is published in the American Journal of Public Health (AJPH). These guidelines are mainly aimed at non-medical cannabis use.


Service Access to Recovery (SAR) is a starting point for persons 16 years and older who are concerned about their substance use and want to understand, discuss and access treatment options. Persons younger than 16 and using opioids will be assessed and referred in priority (parents can call to start the support process).

What can patients expect when they contact SAR?

SAR’s main goal is to help persons navigate the addictions treatment system so they can find the solutions they need and the treatment option that is right for them or their loved ones.

SAR conducts screening and assessments, provides information, support and guidance, triages and refers persons to treatment. This is a bilingual service.

Patients can call (613) 241-5202 to access the program.

For more information on resources and services, visit our Mental Health, Addictions and Substance Use Health Services and Resources webpage.

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