The investigators are conducting a pilot (i.e. a small study) in order to find out the effectiveness and safety of medical cannabis in the management of chronic pain. At the end of this 3 month study, investigators will gather information on how easy it is for patients to enroll and complete the entire study. The results of this pilot study will help the study team design a larger randomized controlled trial.

Chronic pain is defined as pain lasting longer than three months, affects ~20% of Canadian adults. In addition to having a significant negative impact at the individual patient level (i.e., decreased quality of life and functioning), chronic pain is also a main cause of disability and health care use. Opioids are frequently prescribed to manage chronic pain despite limited data on their long term usefulness and has become one of the major contributors to the current opioid crisis in Canada. Chronic pain can potentially be treated with medical cannabis as an adjunct or alternative to opioids due to their similar behavioral, anatomical and biochemical mechanisms. Cannabinoids also potentially prevent the development of tolerance to opioids when co-administered.

Cannabinoids have demonstrated the ability to reduce pain as well as opioid-sparing effects in pre-clinical and clinical studies however further research is needed to identify the optimal make-up, ratio, and dosage of cannabinoids to minimize harms and maximize benefits. Furthermore, studies conducted to date have methodological problems such as short follow-up windows (hours or days) that limit conclusions. The investigators therefore propose a randomized, placebo-controlled trial of oral cannabinoids [CBD (cannabidiol) alone or in combination with THC (delta-9-tetrahydrocannabinol)] for reducing pain disability and opioid use for pain management in chronic pain. However, there are a number of feasibility issues that should be addressed prior to launching a full-scale trial in this area. Some issues have been identified in the literature (e.g., success of blinding) while others are related to the changing socio-medico-legal landscape surrounding cannabis use in Canada.

The purpose of this pilot study is to test the study plan, patient recruitment and compliance with the study procedures. Results of this study may be used as a guide for larger studies and will help us determine if medical cannabis can reduce daily opioid doses and/or decrease pain interference (disability) in chronic pain patients.

This study will aim to recruit 51 patients from the Toronto General Hospital Transitional Pain Service.

Study Procedure: After obtaining the Informed consent, patients will be randomized into one of the three study groups. Patients will either receive CBD oil, CBD+THC oil or placebo orally for 12 weeks. Starting dose will be 1 ml per day. The dose of study drug will be adjusted based on patients' reported efficacy and adverse effects. After starting the study drug, patients will have scheduled study visits either remotely or in-person at 4, 8, and 12 weeks plus a follow up calls or virtual clinic visit(OTN) at 2 and 6 weeks. At every study visit, patients will be asked to complete the questionnaires that will assess their pain level and how it affects their quality of life, opioid use, and side effects if they are experiencing. The investigators will also collect information on: demographic and baseline characteristics (e.g., sex, age, height, weight, and body mass index) and medical history (including prior and concomitant medications) via patient interview or from inspection of medical records. Additionally, symptoms of depression and anxiety will be measured with the validated screening tools at baseline and 12 weeks post-treatment.

Inclusion Criteria:

1. Age ≥ 25 years
2. Able to understand and read English
3. Experiencing chronic, non-palliative pain

Exclusion Criteria:

1. Use of nabilone, nabiximols or cannabis in the 30 days preceding study recruitment
2. Known allergy to cannabis or any cannabinoid
3. Serious ongoing medical issues (i.e., lung, liver, kidney or heart disease) that in the opinion of the Investigator would compromise the safety of the patient
4. Current uncontrolled serious mental disorders such as schizophrenia, or psychosis
5. Currently pregnant or breast-feeding (a negative urine pregnancy test must be obtained for women of child bearing potential during pretreatment evaluation)
6. Men and women planning to start a family in the next 12 weeks
7. Has declared a current alcohol or substance use disorder (excluding opioid use disorder)
8. Currently using Methadone or Buprenorphine
9. Patients who are naïve to pain treatments

The patients, study staff, care providers, adjudicators, data analysts and investigators will be blinded to the active ingredient(s) in the study medication and group allocation. Blinding of all research team members who interact with the patient will avoid biases in communications with, or treatment of, participants based on group allocation. Blinding of research participants will avoid any bias in reporting (e.g., of pain ratings, side effects) and actions/behaviours during the study (e.g., opioid medication dose adjustments) based on group allocation and/or expectations.