Cannabidiol (CBD) Reduces Epileptic Seizures in the Asian Population: Cross-sectional Study for Intractable Epilepsy Patients in Japan


  • Yuji Masataka Green Zone Japan
  • Takeshi Sugiyama
  • Ichiro Takumi Department of Neurosurgery, St. Marianna University School of Medicine, Kanagawa, Japan.
  • Hitoshi Yamamoto Department of Pediatrics, St. Marianna University School of Medicine, Kanagawa, Japan.



cannabidiol, cannnabinoid, dronabinol, epilepsy, seizure, antiepileptic effects, epidiolex


Purpose of study: Despite very strict cannabis regulations in Japan, some cannabidiol (CBD) products have been legally distributed since 2013 and taken by some epilepsy patients. However, its efficacy and safety have not been evaluated.

Basic procedures: A self-administered questionnaire was sent to 38 patients with intractable epilepsy who were taking CBD. The questionnaire sought information on patient background (sex, age) and medical history (diagnosis, type of seizures), characteristics of CBD use (frequency, route of administration), and the safety of CBD use (adverse events, side effects). Patients were also asked about changes in seizure frequency, intensity, and duration; effect on sleep; effect on daytime activity/vitality; increase/decrease in antiepileptic drugs dosage; quality of life (QOL); and caregiver-assessed QOL.

Findings: Responses were received from 28 of 38 patients. The median CBD intake  was 12.0 mg/kg/day. Nine patients (32.1%) were suspected of having an adverse event, but all were mild and no patients discontinued CBD due to adverse events. Fifteen patients (53.6%) reported a decrease in seizure frequency, and 2 patients (7.1%) showed complete resolution of seizures. No significant correlation was found between the patient’s diagnosis and the seizure type or efficacy.

Conclusions: This is the first cross-sectional study of CBD users in Japan, suggesting that CBD may be an effective option for Asian patients with refractory epilepsy, regardless of diagnosis or seizure type.





Original Article