89% of Children With Treatment-Resistant Epilepsy Had Fewer Seizures With CBD Oil

In a multicenter Israeli study of 74 children with severe epilepsy resistant to more than 7 medications, 89% experienced seizure reduction with CBD-enriched cannabis oil, including 18% who had 75-100% fewer seizures.

Tzadok, Michal et al.·Seizure·2016·Moderate EvidenceRetrospective Cohort
RTHC-01286Retrospective CohortModerate Evidence2016RETHINKTHC RESEARCH DATABASErethinkthc.com/research

Quick Facts

Study Type
Retrospective Cohort
Evidence
Moderate Evidence
Sample
N=74

What This Study Found

Researchers reported the experience of five Israeli pediatric epilepsy centers treating 74 children and adolescents (ages 1-18) with intractable epilepsy using CBD-enriched medical cannabis oil (20:1 CBD to THC ratio dissolved in olive oil).

These children had severe, treatment-resistant epilepsy: all had failed more than 7 antiepileptic drugs, and 66% had also failed a ketogenic diet, vagal nerve stimulator, or both. They were treated for an average of 6 months with CBD at doses ranging from 1 to 20 mg/kg/day.

The results were striking: 89% (66 of 74) reported seizure reduction. Of these, 18% had 75-100% reduction, 34% had 50-75% reduction, 12% had 25-50% reduction, and 26% had less than 25% reduction. Five patients (7%) reported seizure worsening.

Beyond seizure control, improvements were observed in behavior, alertness, language, communication, motor skills, and sleep. Adverse effects included somnolence, fatigue, gastrointestinal issues, and irritability.

Key Numbers

74 patients aged 1-18. All failed 7+ antiepileptic drugs. 66% also failed ketogenic diet or VNS. CBD dose: 1-20 mg/kg/day. 89% had seizure reduction: 18% at 75-100%, 34% at 50-75%, 12% at 25-50%, 26% at <25%. 7% had seizure worsening. 5 patients withdrew due to side effects.

How They Did This

Retrospective multicenter study across five Israeli pediatric epilepsy clinics. 74 patients aged 1-18 with intractable epilepsy (resistant to 7+ antiepileptic drugs) were treated with CBD-enriched cannabis oil (20:1 CBD:THC) at 1-20 mg/kg/day for at least 3 months (average 6 months). Seizure frequency was assessed by parental report during clinical visits.

Why This Research Matters

These children represented the most severe and treatment-resistant epilepsy cases. When more than 7 medications and even surgical/device interventions have failed, any seizure reduction is meaningful. The 89% response rate and the breadth of additional improvements are noteworthy for a population with almost no remaining treatment options.

The Bigger Picture

This study, along with similar reports from other countries, built the evidence base that led to the FDA's 2018 approval of Epidiolex (pharmaceutical CBD) for certain pediatric seizure disorders. The Israeli experience was part of a global wave of clinical data demonstrating CBD efficacy in treatment-resistant pediatric epilepsy.

What This Study Doesn't Tell Us

Retrospective design with seizure frequency assessed by parental report rather than objective measurement. No control group, so placebo effects cannot be excluded. The CBD:THC ratio was 20:1, so some effects could be from the small amount of THC. Different patients received different doses. Open-label treatment introduces expectation bias.

Questions This Raises

  • ?What is the optimal CBD dose for different epilepsy types?
  • ?Do the benefits persist long-term, or does tolerance develop?
  • ?Which specific epilepsy syndromes respond best to CBD?
  • ?How much of the effect is from CBD versus the small amount of THC in the formulation?

Trust & Context

Key Stat:
89% of children with intractable epilepsy (failed 7+ drugs) had seizure reduction with CBD oil.
Evidence Grade:
Moderate evidence from a multicenter retrospective study with a meaningful sample size and clinically significant outcomes, though limited by the observational design and subjective seizure reporting.
Study Age:
Published in 2016, before the FDA approved Epidiolex (CBD) for pediatric epilepsy in 2018. This study was part of the evidence base supporting that approval.
Original Title:
CBD-enriched medical cannabis for intractable pediatric epilepsy: The current Israeli experience.
Published In:
Seizure, 35, 41-4 (2016)
Database ID:
RTHC-01286

Evidence Hierarchy

Meta-Analysis / Systematic Review
Randomized Controlled Trial
Cohort / Case-ControlFollows or compares groups over time
This study
Cross-Sectional / Observational
Case Report / Animal Study

Looks back at existing records to find patterns.

What do these levels mean? →

Frequently Asked Questions

Does CBD help children with epilepsy?

In this study of 74 children who had failed more than 7 medications, 89% experienced seizure reduction with CBD-enriched cannabis oil. Since then, pharmaceutical CBD (Epidiolex) has received FDA approval for specific pediatric seizure disorders.

Is CBD safe for children?

In this study, most children tolerated CBD well. Side effects included drowsiness, fatigue, and stomach issues. Five of 74 patients (7%) experienced seizure worsening, and 5 withdrew due to side effects. Close medical supervision is essential.

Read More on RethinkTHC

Cite This Study

RTHC-01286·https://rethinkthc.com/research/RTHC-01286

APA

Tzadok, Michal; Uliel-Siboni, Shimrit; Linder, Ilan; Kramer, Uri; Epstein, Orna; Menascu, Shay; Nissenkorn, Andrea; Yosef, Omer Bar; Hyman, Eli; Granot, Dorit; Dor, Michael; Lerman-Sagie, Tali; Ben-Zeev, Bruria. (2016). CBD-enriched medical cannabis for intractable pediatric epilepsy: The current Israeli experience.. Seizure, 35, 41-4. https://doi.org/10.1016/j.seizure.2016.01.004

MLA

Tzadok, Michal, et al. "CBD-enriched medical cannabis for intractable pediatric epilepsy: The current Israeli experience.." Seizure, 2016. https://doi.org/10.1016/j.seizure.2016.01.004

RethinkTHC

RethinkTHC Research Database. "CBD-enriched medical cannabis for intractable pediatric epil..." RTHC-01286. Retrieved from https://rethinkthc.com/research/tzadok-2016-cbdenriched-medical-cannabis-for

Access the Original Study

Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.

This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.