Canada has had a medical cannabis system since before legalization in 2018. Today people can buy legal cannabis at retail shops, but a medical authorization still exists and offers some advantages. This article explains what the evidence supports for medical use and how the system works.

Where the evidence is strongest

Chemotherapy-related nausea and vomiting. Cannabinoid medicines have shown benefit in some patients, particularly when standard anti-nausea drugs have failed. They are not first-line therapy.

Spasticity in multiple sclerosis. Some trials of cannabis-based medicines show modest improvement in patient-reported spasticity.

Chronic neuropathic pain. Evidence suggests small to moderate benefit for some people, but with side effects, and high-quality long-term data are limited.

Certain severe childhood epilepsies. Purified CBD has regulatory approval in several countries for specific syndromes (see Article 31).

Where evidence is weaker or mixed

• Anxiety, depression, and PTSD: inconsistent, and heavy use may worsen anxiety.
• Insomnia: short-term help for some, but tolerance and rebound problems occur.
• General chronic pain, arthritis, and cancer pain: mixed results.
• Inflammatory bowel disease, Parkinson’s disease, and many other conditions: preliminary.

Medical cannabis is typically not a first-line treatment, and it may be considered after other options have failed.

Risks specific to medical use

• Sedation, dizziness, and cognitive impairment, especially in older adults, who are at higher risk of falls.
• Interactions with other sedating medications.
• Heart rate increases and, rarely, cardiovascular events, so caution is advised for people with heart disease.
• Psychosis risk in vulnerable people (Article 29).
• Dependence and cannabis use disorder.
• Impaired driving.

How access works in Canada

Because cannabis is legal for adults, many patients simply buy from legal retailers. A medical authorization may still help in specific ways:

• Guidance. A clinician can help choose products and monitor effects and interactions.
• Quantity. Medical access can allow larger possession and purchase limits than the recreational system.
• Price and coverage. Some insurers and veterans’ programs cover medical cannabis, and some claim-related tax treatment may apply. Check current rules.
• Product range. Federally licensed sellers can provide medical products by mail.

Under the federal system, a health care practitioner provides a medical document, and the patient registers with a licensed seller. Rules about who can authorize, what the documents must contain, and how products can be bought are set by Health Canada and may change, so confirm current requirements on canada.ca.

Finding a prescriber

Not all physicians are comfortable authorizing cannabis. Some provinces and professional colleges have guidance. Specialty clinics exist, but quality varies. Be cautious about clinics that guarantee approval or that charge high fees without a proper assessment.

Practical advice

• Discuss it with your doctor or pharmacist, especially if you take other medications.
• Choose regulated products with clear THC and CBD labelling.
• Keep a symptom diary to see whether it is actually helping.
• Review regularly. If it isn’t helping, stop rather than continuing out of habit.
• Don’t drive while impaired, and store products securely away from children and pets.

The takeaway

Medical cannabis has real but limited evidence for specific conditions, and it carries real risks. Treat it like any other medicine: a clear target symptom, a trial period, and honest review of whether it works.

Sources: General clinical knowledge and Canadian cannabis regulations. Not freshly searched; verify current Health Canada rules and evidence reviews.