The National Academies of Sciences reviewed 10,000 abstracts and concluded there is conclusive or substantial evidence that cannabis is effective for chronic pain, chemotherapy-induced nausea, and multiple sclerosis spasticity.
Read this if you want a clear summary of what the strongest scientific authority says about which conditions cannabis actually helps.
Conclusive or substantial evidence for pain, nausea, and spasticity
What the researchers found
The National Academies of Sciences, Engineering and Medicine conducted a comprehensive review of the health effects of cannabis, with a 16-member committee analyzing 10,000 recent abstracts across 11 health categories.
For therapeutic effects, the committee found conclusive or substantial evidence that cannabis or cannabinoids effectively treat three conditions: chronic pain in adults, chemotherapy-induced nausea and vomiting, and spasticity associated with multiple sclerosis.
Moderate evidence supported cannabis for improving secondary sleep disturbances. For many other conditions, including appetite improvement, Tourette syndrome, anxiety, PTSD, cancer, irritable bowel syndrome, epilepsy, and neurodegenerative disorders, the evidence was described as limited, insufficient, or absent.
The report specifically identified multiple barriers to cannabis research in the United States that may explain why more conditions have not been adequately studied, suggesting the gaps in evidence reflect regulatory obstacles rather than necessarily a lack of therapeutic potential.
Why it matters
This is one of the most authoritative reviews of cannabis therapeutics ever conducted, coming from the National Academies, the same body that advises the US government on science. Its conclusions carry significant weight in policy discussions and clinical decision-making. The identification of research barriers is equally important, as it acknowledges that absence of evidence does not equal evidence of absence.
The numbers in context
16-member committee. 10,000 abstracts reviewed. 11 health endpoint categories examined. 3 conditions with conclusive or substantial evidence of benefit: chronic pain, chemotherapy-induced nausea, MS spasticity. 1 condition with moderate evidence: secondary sleep disturbances.
How the study worked
The NASEM committee followed key features of a systematic review process, searching relevant databases and reviewing 10,000 recent abstracts. Priority was given to recently published systematic reviews and primary research addressing 11 health categories. Standardized language was used to categorize evidence strength: conclusive, substantial, moderate, limited, or insufficient.
What this study cannot tell us
The review was constrained by the quality and quantity of available research, which the authors acknowledged was itself limited by regulatory barriers. The rapidly evolving landscape of cannabis products and formulations means some findings may not reflect current clinical practice. The committee could only assess published literature, which may not capture all clinical experience.
How to read the evidence
This is a comprehensive evidence review by the National Academies, representing the highest level of evidence synthesis available.
When this study was published
Published in 2018, based on the 2017 NASEM report. Cannabis research has continued to evolve since.
The bigger picture
This NASEM report has become a landmark reference in cannabis medicine. It established a framework for discussing the evidence that separates well-supported therapeutic uses from those that need more research. The report's identification of barriers to research has also influenced ongoing policy debates about cannabis scheduling and research access.
Questions still open
- Will removing research barriers lead to stronger evidence for conditions currently categorized as limited or insufficient? How should the findings about pain, nausea, and spasticity influence clinical prescribing guidelines? Can the evidence gaps for conditions like PTSD and epilepsy be filled with ongoing trials?
Common questions
What conditions has cannabis been proven to treat?
Why isn't there more evidence for other conditions?
Read the original research
The therapeutic effects of Cannabis and cannabinoids: An update from the National Academies of Sciences, Engineering and Medicine report.
European journal of internal medicine, 49, 7-11
Citation
Abrams, Donald I. (2018). The therapeutic effects of Cannabis and cannabinoids: An update from the National Academies of Sciences, Engineering and Medicine report.. European journal of internal medicine, 49, 7-11. https://doi.org/10.1016/j.ejim.2018.01.003
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