Dr. Caroline A. MacCallum

MD, FRCPC (Internal Medicine), BSc Pharm

  • Department of Medicine, Faculty of Medicine, Division of Community Internal Medicine, University of British Columbia (UBC)
  • Department of Medicine, Faculty of Medicine, Division of Palliative Care, UBC
  • Faculty of Pharmaceutical Sciences, UBC
  • Greenleaf Medical Clinic

Dr. Caroline MacCallum is a specialist in internal medicine, with expertise in complex pain and cannabinoid medicine. She is a clinical Assistant Professor in the Department of Medicine; Adjunct Professor in the Faculty of Pharmaceutical Sciences program; and associate member in the Dept. of Palliative Care at the University of British Columbia.

Dr. MacCallum is the medical director of Greenleaf Medical Clinic, where she has assessed and developed cannabinoid treatment plans for more than 5,000 patients using legal medical cannabis approved by Health Canada.

Caroline MacCallum is the primary author of Practical Considerations for Medical Cannabis Administration and Dosing, published in the European Journal of Internal Medicine, which has been cited over 500 times. She is the assistant editor for the Cannabinoids and Pain book by Springer; and first author on eight chapters pertaining to pharmacovigilance including: mental health, impairment, dosing, patient safety (contraindications & drug interactions), use in adolescence, product safety, pain, and opioid substitution.

Dr. MacCallum has presented internationally on the topic of cannabis dosing, safety and polypharmacy reduction/substitution. She has qualified as a medical cannabis expert and testified in arbitration for a claim involving a challenge to Health Canada’s 24-hour rule for cannabis impairment. Dr. MacCallum is currently working on knowledge translation and medical cannabis literacy with university research groups, hospitals, health benefit programs, provincial and national committees to create; guidelines, safe prescribing practices, clinical trials, patient registries and adverse event monitoring.

Her research interests focus on the use of cannabis as an adjuvant to standard of care for complex conditions including: chronic pain, fibromyalgia/chronic fatigue syndrome, neurodevelopmental disorders, post-traumatic stress disorder, and traumatic brain injury; deprescribing/drug substitution; pharmacovigilance and impairment.

UBC Pain Research Network Profile

Vancouver Coastal Health Research Institute Profile

Frontiers (Loop) Science Research Network Profile


Does acute cannabidiol (CBD) use impair performance? A meta-analysis and comparison with placebo and delta-9-tetrahydrocannabinol (THC). Neuropsychopharmacology. 2024 – https://www.nature.com/articles/s41386-024-01847-w

Clinical Application of Cannabis Vaporization: Examining Safety and Best Practices. Cannabis and Cannabinoid Research. 2024 – https://doi.org/10.1089/can.2023.0219

Cannabis vaporisation: Understanding products, devices, and risks. Drug and Alcohol Review. 2023 – https://onlinelibrary.wiley.com/doi/10.1111/dar.13800

Why a distinct medical stream is necessary to support patients using cannabis for medical purposes. Journal of Cannabis Research. 2023 – https://jcannabisresearch.biomedcentral.com/articles/10.1186/s42238-023-00195-8

Clinical Practice Guidelines for Cannabis and Cannabinoid-Based Medicines in the Management of Chronic Pain and Co-Occurring Conditions. Cannabis and Cannabinoid Research. 2023 – https://www.liebertpub.com/doi/epdf/10.1089/can.2021.0156

Cannabidiol as a Harm Reduction Strategy for People Who Use Drugs: A Rapid Review. The Canadian Journal of Psychiatry. 2023 – https://journals.sagepub.com/doi/full/10.1177/07067437231183525

Exploring medical cannabis use in individuals with a traumatic brain injury. Exploration of Medicine. 2023 – https://www.explorationpub.com/Journals/em/Article/1001150

Applying a cannabis impairment framework to medical cannabis patients. Medicinal Usage of Cannabis and Cannabinoids. Academic Press; 2023

Cannabidiol-Associated Hepatotoxicity: A Systematic Review and Meta-Analysis. Journal of Internal Medicine. 2023 – https://doi.org/10.1111/joim.13627

Are Younger Medical Cannabis Users at Risk? Comparing Patterns of Use and Mental Health in Younger and Older Medical Cannabis Dispensary Users. SCHOLINK Children and Teenagers. 2023 – http://www.scholink.org/ojs/index.php/ct/article/view/15802/6891

Peer Reviewer. Ask Your Provider About Cannabis: Increasing Nurse Practitioner Knowledge and Confidence. Cannabis and Cannabinoid Research. 2021 – https://doi.org/10.1089/can.2021.0061

Peer Reviewer. Perspectives of pediatric oncologists and palliative care physicians on the therapeutic use of cannabis in children with cancer. Cancer Rep (Hoboken). 2021 – https://pubmed.ncbi.nlm.nih.gov/34672127/

Rapid response to ‘Medical cannabis or cannabinoids for chronic pain: a clinical practice guideline’. BMJ. 2021 – https://doi.org/10.1136/bmj.n2040

Narouze SN, MacCallum CA. eds. Cannabinoids and Pain. Springer; 2021

Consensus recommendations on dosing and administration of medical cannabis to treat chronic pain: results of a modified Delphi process. Journal of Cannabis Research. 2021 – https://doi.org/10.1186/s42238-021-00073-1

Is medical cannabis safe for my patients?” A practical review of cannabis safety considerations. European Journal of Internal Medicine. 2021 – https://doi.org/10.1016/j.ejim.2021.05.002

Practical strategies using medical cannabis to reduce harms associated with long term opioid use in chronic pain. Frontiers in Pharmacology. 2021 – https://doi.org/10.3389/fphar.2021.633168

Duration of neurocognitive impairment with medical cannabis use: a scoping review. Frontiers in Psychiatry. 2021 – https://doi.org/10.3389/fpsyt.2021.638962

Guidance in Authorizing Cannabis Products Within Primary Care © 2021 The College of Family Physicians of Canada

Canadian clinical practice guidelines for the use of plant-based cannabis and cannabinoid-based products in the management of chronic non-cancer pain and co-occurring conditions: protocol for a systematic literature review. BMJ Open. 2020;10:e036114 – http://dx.doi.org/10.1136/bmjopen-2019-036114

Characterization of mental health in cannabis dispensary users, using structured clinical interviews and standardized assessment instruments. BMC Psychiatry. 2019;19:335 – https://doi.org/10.1186/s12888-019-2324-z

Practical considerations in medical cannabis administration and dosing. European Journal of Internal Medicine. 2018;49 – https://doi.org/10.1016/j.ejim.2018.01.004



This site is dedicated to those patients (and their families and care providers) who have lived with chronic conditions, found improvement in symptoms, function and quality of life with medical cannabis.

My dream is that one day cannabis will be legalized worldwide; stigma and barriers to access will be no more, and patients can experience a better quality of life.

Huge appreciation to my cannabis team who have supported me over the years and without them none of this would be possible:

  • Lindsay Lo
  • Carly Pistawka
  • Michael Boivin
  • Michael Koehn
  • Dr. Shaohua Lu
  • Dr. Lauren Eadie
  • Dr. Alasdair Barr
  • Fonda Betts
  • Tanya Adams
  • Jag Deol
  • Dr. Ethan Russo
  • Dr. Maria Fernanda Arboleda