Priority 12 from the Epilepsy (Canada) PSP

UNCERTAINTY: Are cannabis products (e.g. Marijuana, CBD oil) a safe and effective treatment for seizures alone or in combination with standard treatments (e.g. anti-seizure drugs)?  (JLA PSP Priority 12)
Overall ranking 12
JLA question ID 0110/12
Explanatory note Since its legalization in Canada in 2018, medical cannabis has been of great interest in the treatment of epilepsy. The two major cannabinoids present in the cannabis plant are cannabidiol (CBD) and tetrahydrocannabinol (THC). Reports from patients and families suggest that both of them have anticonvulsant properties, and scientific reports support this claim. In particular, CBD oil can reduce seizure frequency in people with Dravet syndrome or Lennox-Gastaut syndrome. However, the effectiveness for other types of epilepsy and epilepsy syndromes is not clear. In addition, there is a lack of evidence on safety and side effects, recommended dosages and formulations, and interactions with anti-seizure drugs. More research is needed to determine if and how cannabis products can be safely used to treat epilepsy and seizures.  

Gloss, D., & Vickrey, B. (2014). Cannabinoids for epilepsy. Cochrane Database of Systematic Reviews(3). doi:10.1002/14651858.CD009270.pub3

National Institute for Health and Care Excellence. (2019). Cannabidiol with clobazam for treating seizures associated with Dravet syndrome. Technology Appraisal Guidance, TA615. Available from:

National Institute for Health and Care Excellence (2019). Cannabidiol with clobazam for treating seizures associated with Lennox–Gastaut syndrome. Technology Appraisal Guidance, TA615. Available from: 

Health Research Classification System category Neurological 
Extra information provided by this PSP
Original uncertainty examples What is the hypothesis on being able to eradicate the use of anti-seizure medication and treat solely with CBD oil? ~ Should a wider variety of treatment options be considered by MD's? Have alternative therapies ie.cannabis been researched and are they being considered as adjunct treatment options?  ~  How effective is cannabis and what research and white papers have been written to show the efficacy? ~ Is medical marijuana being investigated as a possible treatment for epilepsy and seizures?  Is there treatments that have less of an impact on motor planning such as for patients with Rett syndrome?  
Submitted by People with Seizures x 24, Caregivers x 8, Friend or Family Member x 9, Health Care provider x 3, Community Agency Representative x 3, Other x 2 
PSP information
PSP unique ID 0110
PSP name Epilepsy (Canada)
Total number of uncertainties identified by this PSP. 96  (To see a full list of all uncertainties identified, please see the detailed spreadsheet held on the JLA website)
Date of priority setting workshop 6th & 7th April 2021