Phase 3 trials of pharmaceutical CBD (Epidiolex) demonstrated efficacy and safety for Dravet and Lennox-Gastaut syndromes, while artisanal cannabis products remain unstandardized and unvalidated.
Read this if you or a family member has treatment-resistant epilepsy and wants to understand the evidence for CBD.
Phase 3 RCTs confirmed CBD (Epidiolex) efficacy for Dravet and Lennox-Gastaut syndromes
What the researchers found
This review traced the evolution of cannabis-based epilepsy treatment from millennia of traditional use to modern randomized controlled trials.
The strongest evidence centered on Epidiolex (purified CBD at 100 mg/mL). Open-label studies showed efficacy with an adequate safety profile in children and young adults with a spectrum of treatment-resistant epilepsies. Phase 3 RCTs then confirmed efficacy and safety specifically for Dravet syndrome and Lennox-Gastaut syndrome at doses of 10 and 20 mg/kg/day.
The review highlighted a critical distinction between pharmaceutical-grade CBD and artisanal preparations available from dispensaries. While Epidiolex has undergone rigorous clinical evaluation, the dispensary products vary widely in composition and have no validated safety or efficacy data.
The authors noted the importance of the placebo effect in cannabis epilepsy research, given intense media attention and strong parental beliefs in natural products. Drug interactions, particularly with clobazam, were identified as an important safety consideration.
Why it matters
Treatment-resistant epilepsy affects 30% of epilepsy patients and carries severe morbidity and mortality. Epidiolex represents the first plant-derived cannabinoid to undergo rigorous clinical trial evaluation, setting a precedent for the field.
The numbers in context
30% of epilepsy patients are treatment-resistant. Epidiolex studied at 10 and 20 mg/kg/day. Phase 3 RCTs completed for Dravet syndrome and Lennox-Gastaut syndrome. 25 states plus DC had medical marijuana programs.
How the study worked
Review of case reports, small series, surveys, open-label studies, and Phase 3 RCTs of cannabinoids for treatment-resistant epilepsy, with focus on CBD (Epidiolex) for Dravet and Lennox-Gastaut syndromes.
What this study cannot tell us
The review captures a moment in time before FDA approval of Epidiolex (which came in 2018). Long-term safety data were still limited. The focus on Dravet and LGS may not apply to other epilepsy types. Drug interactions require ongoing study.
How to read the evidence
Review incorporating Phase 3 RCT data, the highest tier of clinical evidence. Strong because the RCTs were large, placebo-controlled, and confirmatory.
When this study was published
Published in 2017, before FDA approval of Epidiolex in 2018.
The bigger picture
The Epidiolex story represents a model for how cannabinoid medicine should develop: from traditional use and case reports through controlled trials to regulatory approval. It also highlights the tension between pharmaceutical development and the dispensary-based access that millions of patients use without equivalent evidence.
Questions still open
- Will CBD show efficacy for other epilepsy types beyond Dravet and LGS? Can artisanal CBD products be standardized to match pharmaceutical quality? What is the optimal long-term dosing strategy?
Common questions
Does CBD help with epilepsy?
Is CBD from a dispensary the same as Epidiolex?
Read the original research
Cannabinoids in treatment-resistant epilepsy: A review.
Epilepsy & behavior : E&B, 70(Pt B), 341-348
Citation
O'Connell, Brooke K; Gloss, David; Devinsky, Orrin. (2017). Cannabinoids in treatment-resistant epilepsy: A review.. Epilepsy & behavior : E&B, 70(Pt B), 341-348. https://doi.org/10.1016/j.yebeh.2016.11.012
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