A meta-analysis of three randomized trials found adjunctive CBD increased the chance of achieving 50% seizure reduction by 69% in Dravet syndrome patients.
Neurologists, epilepsy specialists, parents of children with Dravet syndrome, and pharmaceutical researchers.
69% higher chance of 50%+ seizure reduction with CBD (RR 1.69)
What the researchers found
Pooling three RCTs with 359 participants (228 CBD, 131 placebo), adjunctive CBD was associated with a 69% higher likelihood of achieving 50% or greater reduction in convulsive seizures (RR 1.69, 95% CI 1.21-2.36, p=0.002). However, CBD also led to higher treatment discontinuation (RR 3.12) and side effects including somnolence, decreased appetite, diarrhea, and elevated liver enzymes.
Why it matters
Dravet syndrome is among the most severe drug-resistant epilepsies. This meta-analysis provides the highest level of evidence confirming that CBD offers meaningful seizure reduction for these patients.
The numbers in context
3 RCTs; 359 participants; 50% responder rate RR 1.69 (p=0.002); treatment discontinuation RR 3.12; common AEs: somnolence, appetite decrease, diarrhea, elevated liver enzymes.
How the study worked
Systematic review and meta-analysis of three randomized, placebo-controlled, double-blind trials of plant-derived pharmaceutical CBD (Epidiolex) as adjunctive treatment for Dravet syndrome seizures.
What this study cannot tell us
Only three trials available; relatively short treatment periods; all used the same pharmaceutical CBD formulation (Epidiolex), so results may not generalize to other CBD products.
How to read the evidence
Strong: meta-analysis of three randomized, placebo-controlled, double-blind trials.
When this study was published
Published 2020.
The bigger picture
This meta-analysis helped solidify the evidence base that led to regulatory approval of CBD for Dravet syndrome in multiple countries. It represents one of the clearest success stories for cannabinoid medicine.
Questions still open
- Can longer treatment maintain seizure reduction? How do liver enzyme elevations change with prolonged use?
Common questions
How much does CBD reduce seizures in Dravet syndrome?
What are the main side effects?
Read the original research
Adjunctive Cannabidiol in Patients with Dravet Syndrome: A Systematic Review and Meta-Analysis of Efficacy and Safety.
CNS drugs, 34(3), 229-241
Citation
Lattanzi, Simona; Brigo, Francesco; Trinka, Eugen; Zaccara, Gaetano; Striano, Pasquale; Del Giovane, Cinzia; Silvestrini, Mauro. (2020). Adjunctive Cannabidiol in Patients with Dravet Syndrome: A Systematic Review and Meta-Analysis of Efficacy and Safety.. CNS drugs, 34(3), 229-241. https://doi.org/10.1007/s40263-020-00708-6
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