Medical Cannabis for the Management of Pain and Quality of Life in Chronic Pain Patients: A Prospective Observational Study

Pain Med. 2020 Nov 1;21(11):3073-3086. doi: 10.1093/pm/pnaa163.


Objective: To evaluate the short-term and long-term effects of plant-based medical cannabis in a chronic pain population over the course of one year.

Design: A longitudinal, prospective, 12-month observational study.

Setting: Patients were recruited and treated at a clinic specializing in medical cannabis care from October 2015 to March 2019.

Subjects: A total of 751 chronic pain patients initiating medical cannabis treatment.

Methods: Study participants completed the Brief Pain Inventory and the 12-item Short Form Survey (SF-12), as well as surveys on opioid medication use and adverse events, at baseline and once a month for 12 months.

Results: Medical cannabis treatment was associated with improvements in pain severity and interference (P < 0.001) observed at one month and maintained over the 12-month observation period. Significant improvements were also observed in the SF-12 physical and mental health domains (P < 0.002) starting at three months. Significant decreases in headaches, fatigue, anxiety, and nausea were observed after initiation of treatment (P ≤ 0.002). In patients who reported opioid medication use at baseline, there were significant reductions in oral morphine equivalent doses (P < 0.0001), while correlates of pain were significantly improved by the end of the study observation period.

Conclusions: Taken together, the findings of this study add to the cumulative evidence in support of plant-based medical cannabis as a safe and effective treatment option and potential opioid medication substitute or augmentation therapy for the management of symptoms and quality of life in chronic pain patients.

Keywords: Cannabis; Medical; Opioids; Pain; Quality of Life.

Publication types

  • Observational Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Analgesics, Opioid
  • Chronic Pain* / drug therapy
  • Humans
  • Medical Marijuana* / therapeutic use
  • Prospective Studies
  • Quality of Life


  • Analgesics, Opioid
  • Medical Marijuana