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More than half of patients prescribed medical cannabis for chronic musculoskeletal pain stop using it within a year, according to new research from Philadelphia that raises fresh questions about the drug's longevity and its role in long-term pain management—especially among older adults.

The study, "Discontinuation rates and predictors of Medical Cannabis cessation for chronic musculoskeletal pain, " published in PLOS One by researchers from the Rothman Institute Foundation for Opioid Research & Education, found that 57.9% of a group of 78 Pennsylvania patients certified for medical cannabis chose to discontinue treatment within twelve months, with nearly half—44.7%—quitting in the first three months.

The retrospective analysis tracked patients newly certified for cannabis through the state's medical marijuana program to see if they renewed their certifications or sought treatment elsewhere over two years. The only statistically significant predictor of stopping was age: those who discontinued were, on average, about seven years older than those who continued, with mean ages of 71.5 years and 64.5 years, respectively.

Baseline measures of physical and mental health, known as PROMIS Global Physical Health and Global Mental Health scores, did not differ between the two groups, indicating that the decision to quit was unrelated to initial overall health status.

Contrary to what some pain specialists might expect, the origin of a patient's pain—whether in the low back, neck, joints, or other regions—was not a significant driver of discontinuation. Although a slightly higher share of patients who stopped cannabis reported low back pain, the difference was not substantial enough to be statistically meaningful.

Instead, the findings hint at a complex mix of reasons—ranging from treatment dissatisfaction and side effects to the pursuit of more definitive interventions like injections or surgery—that shape whether a patient persists with cannabis.

Comparison of age between patients who discontinued vs. Continued Medical Cannabis (MC) use after 1 Year. Credit: PLOS One (2025). DOI: 10.1371/journal.pone.0329897

According to co-author Dr. Asif M. Ilyas, President of the Rothman Opioid Foundation in Philadelphia, a Professor of Orthopaedic Surgery at Thomas Jefferson University, and an Associate Dean of Clinical Research at Drexel University College of Medicine, these high drop-off rates indicate that "despite growing enthusiasm and widespread adoption, medical cannabis does not meet expectations for a significant subset of chronic pain patients."

Lead author Dr. Mohammad Khak adds that because pain type and baseline health were not decisive factors, other influences—such as perceptions of benefit, daily function, drug costs, or access to consistent product quality—may play an essential role in whether patients stay the course.

The authors caution that their study, while among the first to carefully monitor one-year certification status for medical cannabis in orthopedic pain patients, leaves key questions unanswered. Specific details about cannabis formulation, dosage, and method of delivery were not consistently documented, nor were side effects, functional improvements, or patients' perceptions of relief.

This makes it unclear whether discontinuation was due to a lack of effectiveness, adverse effects, financial burden, or even symptom improvement to the point where cannabis was no longer needed. They also point out that their sample was taken from a single institution's patient population and may not represent broader trends.

The findings arrive at a time when medical cannabis use is quickly expanding across the United States, highlighting the need for more personalized approaches—especially for older patients, who showed the highest likelihood of stopping use.

The research team urges larger, multi-center, prospective studies that collect more detailed data on dosing, delivery methods, side effects, and patient satisfaction, to identify which patients are most likely to benefit from medical cannabis and for how long. Until then, they believe, physicians and patients should approach long-term cannabis therapy with realistic expectations and an openness to adjustments based on early responses.

More information: Mohammad Khak et al, Discontinuation rates and predictors of Medical Cannabis cessation for chronic musculoskeletal pain, PLOS One (2025). DOI: 10.1371/journal.pone.0329897  Journal information: PLoS ONE