CBD for Dravet Syndrome: The Landmark Trial
What Researchers Found About Epilepsy and Cannabis
The Study at a Glance
Published
New England Journal of Medicine, 2017
Researchers
NYU Langone Medical Center (United States)
Study Type
Randomized Controlled TrialParticipants
120 patients · 14 weeks
Key Finding
In this groundbreaking NEJM trial, children with drug-resistant Dravet syndrome saw their monthly seizures cut from 12.4 to 5.9 with CBD—a 53% reduction. Nearly half of patients achieved at least 50% seizure reduction, and 5% became completely seizure-free.
Key Finding: In this groundbreaking NEJM trial, children with drug-resistant Dravet syndrome saw their monthly seizures cut from 12.4 to 5.9 with CBD—a 53% reduction. Nearly half of patients achieved at least 50% seizure reduction, and 5% became completely seizure-free.
What Researchers Studied About Epilepsy and Cannabis
Dravet syndrome is one of the most devastating forms of childhood epilepsy. Children suffer frequent, severe seizures that don't respond to standard medications, and the condition carries a high mortality rate.
This landmark 2017 trial in the New England Journal of Medicine tested whether pharmaceutical-grade CBD (cannabidiol) could help these children when other drugs had failed.
The results of this trial led directly to FDA approval of Epidiolex, the first cannabis-derived medication approved by the FDA.
How This Randomized Controlled Trial Was Conducted
Researchers conducted a rigorous double-blind, placebo-controlled trial:
• 120 children and young adults with Dravet syndrome • All had drug-resistant seizures despite trying multiple medications • Randomly assigned to CBD (20 mg/kg/day) or placebo • Continued standard seizure medications alongside study drug • 4-week baseline period to establish seizure frequency • 14-week treatment period • Primary outcome: change in convulsive seizure frequency
Epilepsy Treatment Results
The Main Results:
- 1Monthly seizures dropped from 12.4 to 5.9 with CBD (53% reduction)
- 2Placebo group: seizures went from 14.9 to 14.1 (5% reduction)
- 343% of CBD patients achieved 50%+ seizure reduction vs 27% placebo
- 462% had overall condition improvement vs 34% placebo
- 55% became completely seizure-free (vs 0% on placebo)
- 6Side effects included diarrhea, vomiting, fatigue, and liver function changes
By the Numbers
| Statistic | What It Means |
|---|---|
| 53% | reduction in monthly convulsive seizures with CBD |
| 43% | of patients achieved 50%+ seizure reduction |
| 5% | of CBD patients became seizure-free |
| 120 | children and young adults participated |
reduction in monthly convulsive seizures with CBD
of patients achieved 50%+ seizure reduction
of CBD patients became seizure-free
children and young adults participated
What This Means for Epilepsy Patients
This trial changed the treatment landscape for severe childhood epilepsy:
The breakthrough: For children with Dravet syndrome who had tried everything, CBD offered real hope. Seizures were cut in half on average—from about 12 per month to 6.
Who responded: • 43% achieved at least 50% seizure reduction • 62% had noticeable improvement in overall condition • 5% became seizure-free
Side effects to know about: • Diarrhea, vomiting, and fatigue were common • Some patients had elevated liver enzymes • More patients withdrew from the CBD group due to side effects
What this means for families: If your child has Dravet syndrome or other drug-resistant epilepsy, pharmaceutical CBD (Epidiolex) is now an FDA-approved option. This trial provided the evidence that made approval possible.
Important note: This used pharmaceutical-grade CBD at specific doses. Over-the-counter CBD products are not equivalent and may not have the same effects.
Quick Answers: Epilepsy and Cannabis
Direct answers based on the findings of this study:
Research Summary: Answers are based on published peer-reviewed studies and represent research findings, not medical recommendations. Individual results may vary. Always consult a healthcare provider before making treatment decisions.
Does CBD help Dravet syndrome seizures?
Yes, CBD significantly reduces seizures. A 2017 NEJM trial of 120 patients found CBD reduced convulsive seizures by 53% (from 12.4 to 5.9 per month) vs only 5% with placebo. 43% achieved 50%+ seizure reduction.
Source: Devinsky et al., New England Journal of Medicine, 2017 (PMID: 28538134)
Is CBD FDA approved for epilepsy?
Yes, CBD is FDA-approved for Dravet. Based on this NEJM trial and others, pharmaceutical CBD (Epidiolex) received FDA approval in 2018 for Dravet syndrome and Lennox-Gastaut syndrome with 53% seizure reduction.
Source: Devinsky et al., New England Journal of Medicine, 2017 (PMID: 28538134)
What dose of CBD for Dravet syndrome?
20 mg/kg/day in FDA trials. The FDA-approval trial used 20 mg/kg/day of pharmaceutical CBD (Epidiolex). At this dose, seizures dropped 53% and 43% of patients achieved 50%+ reduction. Dosing requires neurologist supervision.
Source: Devinsky et al., New England Journal of Medicine, 2017 (PMID: 28538134)
This is educational content, not medical advice
The research summarized here is for informational purposes only. Individual results may vary, and what works in studies may not work the same way for everyone. Always consult with a qualified healthcare provider before making changes to your treatment plan or starting medical cannabis therapy.
Important Limitations
This study has some caveats to keep in mind when interpreting the results:
- Relatively short 14-week treatment period
- Side effects led to more withdrawals in CBD group
- Specific to Dravet syndrome—may not apply to all epilepsy types
- Used pharmaceutical-grade CBD, not commercial CBD products
- Liver function monitoring required
The Bottom Line on Cannabis for Epilepsy
This landmark NEJM trial demonstrated that pharmaceutical CBD can dramatically reduce seizures in children with drug-resistant Dravet syndrome—cutting seizures by 53% compared to just 5% with placebo. The study led directly to FDA approval of Epidiolex and established CBD as a legitimate treatment for severe pediatric epilepsy. For families devastated by Dravet syndrome, this represents one of the most significant treatment advances in years.
Do You Qualify for Medical Marijuana?
If you're living with Epilepsy, you may qualify for a medical marijuana card. Our licensed physicians can evaluate you from home via telehealth.
Related Research & Resources
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- CBD for Lennox-Gastaut Syndrome: The Trial Behind FDA Approval
- Cannabis Benefits and Risks: What 101 Studies Reveal
- Cannabinoids in Children: Safety Data from 23 Clinical Trials
- CBD Significantly Reduces Seizures in Tuberous Sclerosis: Major Trial
- Which Cannabinoid Works for What? The Definitive Review of 152 Trials
Condition Research
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Source
Devinsky O, Cross JH, Laux L, et al. "Trial of Cannabidiol for Drug-Resistant Seizures in the Dravet Syndrome" New England Journal of Medicine. 2017. DOI: 10.1056/NEJMoa1611618
Important Information
Study Age: This study was published 9 years ago. Newer research may have updated or refined these findings.
Not Medical Advice: This research summary is for educational purposes only. It should not be used to diagnose, treat, cure, or prevent any disease or medical condition. Always consult a qualified healthcare provider before starting or changing any treatment.
Individual Variation: Research findings represent group averages. Your individual response to cannabis may differ based on genetics, other medications, underlying conditions, and many other factors.
Last reviewed: January 24, 2026
Important Notices
Research Summary Disclaimer
This content represents our interpretation of published scientific research for educational purposes. It should not be used to make treatment decisions without consulting a qualified healthcare provider. Individual results may vary from study findings.
FDA Notice
These statements have not been evaluated by the FDA. Cannabis is not intended to diagnose, treat, cure, or prevent any disease. The FDA has not approved cannabis for any medical condition except specific prescription medications.
Copyright & Fair Use
Research summaries are provided under fair use (17 U.S.C. § 107) for educational purposes. We provide brief summaries with attribution, not full reproductions. All studies remain the intellectual property of their respective authors and publishers.
Data Sources
Study information sourced from PubMed®, U.S. National Library of Medicine. Inclusion does not imply endorsement by NLM, NIH, or the federal government.
For complete information, see our Terms of Use and Research Content Policy.
FAQs: Cannabis for Epilepsy
Does CBD help Dravet syndrome?
Yes. A landmark NEJM trial showed pharmaceutical CBD reduced convulsive seizures by 53% in children with Dravet syndrome, compared to only 5% reduction with placebo. This led to FDA approval of Epidiolex for Dravet syndrome.
What is the dose of CBD for Dravet syndrome?
20 mg/kg/day was used in trials. The trial used 20 mg per kilogram of body weight per day of pharmaceutical-grade CBD (Epidiolex). Dosing should always be determined by a neurologist, as this requires prescription medication and monitoring.
Are there side effects of CBD for epilepsy?
Yes. The trial found diarrhea, vomiting, fatigue, somnolence, and elevated liver enzymes occurred more frequently with CBD. Liver function monitoring is required when using Epidiolex.