News Release

Medical cannabis study reveals patterns of cannabis use and consumption

Image of an orange prescription bottle lying on top of a prescription paper pad that says “Rx” on it. There are nuggets of marijuana coming out of the bottle onto the prescription pad
Credit: Getty Images.

As of April 2023, 38 states in the U.S. allow for the medical use of marijuana. Despite the increasing use of cannabis products for medical purposes, state programs do not currently have consistent guidelines for the use of the two most commonly used compounds — cannabidiol (CBD) and tetrahydrocannabinol (THC) — being dispensed and consumed by patients. 

Recently published in Science Direct, a study led by the University of Minnesota in partnership with Vireo Health, a leading multi-state medical marijuana company, looks to bridge this knowledge gap. 

Both CBD and THC interact with the body in complicated ways, which means that symptom control and side effects vary greatly from person-to-person. The lack of the standardized procedures for state-run medical cannabis programs makes it difficult to predict patient response, particularly when taking into account that patients in these programs may have comorbid conditions and unanticipated and highly variable drug interactions with existing medications.

“Our past data shows blood concentrations of CBD and THC can vary widely among patients and according to fat content in food, indicating possible inconsistent exposure that could lead to variations in response and unanticipated side effects,” said Angela Birnbaum, a professor in the Department of Experimental and Clinical Pharmacology in the College of Pharmacy and the lead author on the paper.

Researchers analyzed data from approximately 50% of all registered medical cannabis users in Minnesota between June 2016 and November 2019, all of whom were enrolled in the program with Vireo Health. In order to characterize the extent of exposure to cannabis products, they examined CBD and THC content of dispensed products and dosing among patients with qualifying conditions, by age and by which cannabis products were used. 

The study found:

  • Approximately 60% of patients receiving cannabis had indications of intractable pain. As the largest population of patients, there were significant differences in dosages between older and younger adults within the same diagnosis, which raises questions about factors that contribute to the use of varied dosages in older adults. 
  • Although data shows that CBD is effective for preventing seizures in epilepsy patients, a majority of these patients received formulations containing both THC and CBD. With the complex pharmacokinetics of both THC and CBD, the introduction of THC to this population highlights the importance of further research on the interplay of THC and CBD to better predict patient responses. 

The study provides data from a program where product choice, major cannabinoid quantities and doses received are based on pharmacist selection and patient preference rather than based on a physician’s prescription. 

“Little information is available for most medical cannabis formulations and for particular patient populations,” said Dr. Birnbaum. “More research is needed to understand the long-range influence of cannabis use, especially in older adults who are typically receiving multiple medications and have an increased potential for drug-drug interactions.”

The researchers noted that more investigation is also needed to examine if clinically significant side effects are related to specific CBD and THC dosages.

Funding was provided by the MacMillan Innovative Epilepsy Research and Education Fund and the University of Minnesota Medical Discovery Team on Addiction’s Pilot Grant. 


About the College of Pharmacy

Founded in 1892, the University of Minnesota College of Pharmacy is the only pharmacy school in Minnesota, with campuses in the Twin Cities and in Duluth. The College of Pharmacy improves health through innovative education, pioneering research and interdisciplinary practice development that attends to the diverse needs of the people of Minnesota and the world. Learn more at

About the Medical Discovery Team on Addiction

The University of Minnesota's Medical Discovery Team on Addiction is a multidisciplinary initiative within the University of Minnesota’s Medical School to advance research and treatment in the field of drug addiction. The overarching goal of the Medical Discovery Team on Addiction is to link brain-based discoveries to new therapeutic approaches to treat or prevent addiction. The State of Minnesota has appropriated significant funds for the Medical School to enhance our capacity to build a world-class, neuroscience-based program for the study and treatment of addiction.

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