Preliminary Results Show Cannabidiol Reduces Seizures in Epilepsy

Preliminary results from an open-label study on the use of cannabidiol for the treatment of severe, treatment-resistant epilepsy indicate that the marijuana-derived liquid may reduce seizure frequency.

The results, reported ahead of a formal presentation at the upcoming American Academy of Neurology Annual Meeting in Washington, D.C., are a promising step forward for the use of medical marijuana in the treatment of epilepsy.

The study included 213 participants, median age 11, with forms of severe epilepsy, including Dravet syndrom Lennox-Gastaut syndrome. Overall, 137 people completed the 12-week study, with a 54% average decrease in seizures. Those with Dravet syndrome (23) saw convulsive seizures reduced by 53%, and those with Lennox-Gastaut (11) saw a 55% reduction in atonic seizures.

Twelve participants had to stop taking the liquid drug — a component of marijuana that does not include psychoactive compounds — due to side effects. Other side effects that affected more than 10% of participants included drowsiness (21%), diarrhea (17%), tiredness (17%), and decreased appetite (16%).

“So far there have been few formal studies on this marijuana extract,” study author Orrin Devinsky, MD, head of the NYU Langone Comprehensive Epilepsy Center, said. “These results are of great interest, especially for the children and their parents who have been searching for an answer for these debilitating seizures.”

While the study indicates that cannabidiol is generally well tolerated, larger, placebo-controlled, double-blind trails are needed to measure efficacy.

The call for further research was echoed by the American Epilepsy Society, who said in a statement: 

“At present, the epilepsy community does not know if marijuana is a safe and effective treatment nor do we know the long-term effects that marijuana will have on learning, memory and behavior, especially in infants and young children. Studies like the one presented at the AAN meeting help increase our understanding but much more is needed.”

The organization, which expressed its support of Devinsky’s study, also clarified that the cannabidiol used in the study is different from artisanal compounds being utilized by families and patients in states where marijuana, both recreational and medicinal, is legalized. “In most cases, the families and children who have been using CBD oils outside of this study, have been receiving highly variable artisanal preparations with unverified levels of cannabis oil. This has resulted in many different outcomes from those presented in Dr. Devinsky’s study.”


  1. Devinsky O, et al. Epidiolex (Cannabidiol) in Treatment Resistant Epilepsy. Presented at: American Academy of Neurology Annual Meeting; April 18-25, 2015: Washington, D.C.
  2. AAN Press Release