As a new review highlights significant gaps in the evidence base for medical cannabis, researchers have called for more rigorous studies and access to “balanced information” to support healthcare professionals and their patients.
The authors of a new comprehensive review have concluded that medical cannabis lacks adequate scientific backing for most of the conditions it is commonly used to treat. But responding to the findings, other researchers in the field say the study may not present a balanced picture of the evidence.
The paper, published in JAMA and led by researchers at UCLA Health, reviewed more than 2,500 articles published from January 2010 to September 2025, including randomised trials, meta-analyses and clinical guidelines.
More than 120 studies were prioritised based on their large samples, recency, topics covered and relevance.
The review confirmed that pharmaceutical-grade cannabinoids approved by the US Food and Drug Administration have demonstrated effectiveness but only in a narrow range of conditions.
These include medications for HIV/AIDS-related appetite loss, chemotherapy-induced nausea and vomiting and certain severe pediatric seizure disorders such as Dravet syndrome and Lennox-Gastaut syndrome.
For most other conditions, including chronic pain, anxiety and insomnia, the evidence remains either ‘inconclusive or lacking’, the review found.
While more than half of people who use medical cannabis report using it for chronic pain, current clinical guidelines recommend against cannabis-based medicines as first-line treatment for chronic pain.
‘Significant gaps’ between public perception and scientific evidence
The review’s first author, Dr Michael Hsu of UCLA Health, said there is a gap in understanding between the public and the most recent scientific evidence on its purported medical benefits.
“While many people turn to cannabis seeking relief, our review highlights significant gaps between public perception and scientific evidence regarding its effectiveness for most medical conditions,” said Hsu, health sciences clinical assistant professor at the UCLA Health Department of Psychiatry and Biobehavioral Sciences.
“Clear guidance from clinicians is essential to support safe, evidence-based decision-making when discussing medical cannabis with their patients.”
The review also highlighted potential health risks associated with cannabis use, emphasising that clinicians should carefully screen patients for cardiovascular disease and psychotic disorders, evaluate potential drug interactions and assess whether the risks outweigh the benefits before considering THC-containing products for medical purposes.
The authors acknowledged several limitations of the review, including that it did not conduct a formal risk of bias assessment of the included studies. Several of those included were observational, with variations in their design, patient characteristics and cannabis products tested.
Healthcare professionals and patients deserve ‘balanced information’
But some researchers in the field have highlighted other issues with the quality of the research findings.
Dr Simon Erridge, Director of Research at Curaleaf Clinic, who has co-authored more than 30 peer-reviewed papers on medical cannabis, told Cannabis Health he had concerns about the “transparency” of how studies were selected and the authors’ tendency to “emphasise negative outcomes”.
“The recent JAMA review on therapeutic cannabis use provides a curated overview of the evidence base at present. However, as a researcher in this field, I have concerns about the transparency of how studies were selected for inclusion,” he told Cannabis Health.
“The methodology lacks clarity about why certain studies were included, whilst others examining similar outcomes may have been excluded.”
In 2023, the BMJ published an umbrella review which examined similar evidence. While both papers reached similar conclusions regarding the evidence for the use of cannabidiol in epilepsy and cannabis-based medicines for conditions such as multiple sclerosis, chronic pain, and inflammatory bowel disease, Erridge says that the BMJ authors used “clearer methodology”.
“There appears to be a tendency in the JAMA review to emphasise negative outcomes whilst giving less prominence to research suggesting therapeutic benefits,” he says.
“The BMJ umbrella review presents this evidence in a more balanced framework, clearly acknowledging both risks and benefits to the reader.”
Erridge adds: “Healthcare professionals and ultimately patients deserve access to balanced information that neither overemphasises benefit nor unnecessarily amplifies concerns. Unfortunately, this article falls short of this.”
High-quality, long-term studies are still lacking
What all researchers agree on is that high-quality, long-term studies are still lacking for the use of medical cannabis in many indications.
Hsu said patients deserve “honest conversations about what the science does and doesn’t tell us about medical cannabis,” and called for “more rigorous studies” to “provide clearer guidance and improve clinical care”.
Erridge, who leads the UK Medical Cannabis Patient Registry with over 50,000 patients now enrolled, argues that real-world evidence can help bridge this gap.
“There is a pressing need for more funded research in medical cannabis,” he says.
“What both reviews ultimately demonstrate is that despite increasing clinical use, we still lack high-quality, long-term evidence for many indications.
“This evidence gap highlights why real-world evidence generation through initiatives such as the UK Medical Cannabis Registry remains essential.”
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