Study Analyzes Long-Term Effects of Medical Cannabis for Various Conditions

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A recently published study analyzed the long-term effects of medical cannabis (MC) for patients in Australia (1). As the abstract noted, over one million new patients with chronic health conditions in Australia have been prescribed medical cannabis since 2016, and about half of the country’s population has a chronic condition. The study, “Improvements in health-related quality of life are maintained long-term in patients prescribed medicinal cannabis in Australia: The QUEST Initiative 12-month follow-up observational study,” was published in PLOS One in April 2025. Real-world evidence from medical cannabis patients is needed to shape policy and regulation, the introduction noted.

In 2016, legislation allowed patients who were not responding to conventional treatments to be prescribed medical cannabis by a clinician regulated by the Therapeutic Goods Administration. This study aimed to evaluate the health-related quality of life (HRQL) along with pain, fatigue, sleep, anxiety, depression, and motor function for patients prescribed a medical cannabis oil between November 2020 and December 2021. Changes were assessed using the QUEST initiative (QUality of life Evaluation STudy). In this study, 2353 surveys were completed by the participants who were ages 18–97 years and diagnosed with a chronic condition including musculoskeletal pain, neuropathic pain, insomnia, anxiety, and mixed depressive and anxiety disorder. The patients each had purchased the same medical cannabis products: 50ml bottles of cannabis oil with four THC and CBD ratio options.

The patients completed the surveys electronically at baseline, then at 2 weeks, and then monthly at three months, then at 5-, 7-, 9-, and 12-months after beginning medical cannabis. Results from three months were reported in prior publications.

Results include:

• Improvements in HRQL, fatigue, pain, and sleep for people with chronic health conditions were seen, along with improvements in pain for participants with chronic pain, improvements in sleep disturbance for participants with insomnia, improved depression scores for patients with depression, and improved anxiety scores in patients with anxiety
• The three-month improvements were maintained through the 12-month period
• Greater odds of improvements in fatigue, insomnia, anxiety, and depression were associated with average daily doses of THC-dominant medical cannabis, compared with CBD:THC-balanced medical cannabis
• Quality of life was improved for participants with movement disorders, but significant improvements in upper extremity function scores were not seen

All improvements that were observed were statistically significant, the researchers stated. As strengths of the study, researchers noted the wide range of conditions and locations of patients, and that the medical cannabis oil was titrated to doses used in clinical practice. For limitations, the researchers noted that there was no control group and that the loss of some participants during follow-up could result in possible bias.

“In clinical practice, prescribing MC to patients with chronic health conditions may improve patients’ pain, fatigue, insomnia, anxiety, and depression and overall HRQL,” the researchers stated as clinical implications of the study results. “Current clinical guidelines support prescribing MC to patients who are interested in trialling it for conditions not responding to conventional treatments, and our findings suggest any improvements would be apparent quickly and maintained long-term. Evidence on optimal CBD:THC ratios for different health conditions is emerging and will improve prescribing practices.”

Reference

1. Tait, M-A.; Costa, DSJ.; Campbell R, Warne LN.; Norman R.; Schug S.; Rutherford, C. Improvements in health-related quality of life are maintained long-term in patients prescribed medicinal cannabis in Australia: The QUEST Initiative 12-month follow-up observational study. PLoS ONE. 2025. DOI: 10.1371/journal.pone.0320756