What does cannabis research say about epilepsy? We've analyzed 9 peer-reviewed studies to give you an honest, evidence-based overview.
Multiple high-quality studies support cannabis for this condition.
Study found evidence of effectiveness
Results varied by condition or dose
No significant effect found
* Outcomes are based on our curated selection of research reviews. Individual study quality varies.
About This Research Summary: The information below aggregates findings from multiple peer-reviewed studies on cannabis and epilepsy. This is for educational purposes only.
Research summaries are our interpretations of published studies. Individual responses to cannabis vary significantly. These findings do not guarantee similar results for any individual.
Study data sourced from PubMed®. Not evaluated by the FDA. See our Research Content Policy.
Epilepsy affects over 3 million Americans and is characterized by recurrent, unprovoked seizures caused by abnormal electrical activity in the brain. It encompasses many different seizure types and epilepsy syndromes, ranging from mild to severely disabling. About one-third of epilepsy patients have drug-resistant (refractory) epilepsy—their seizures aren't adequately controlled by standard anti-seizure medications. For these patients, treatment options are limited and may include brain surgery, nerve stimulation devices, or dietary therapies. The search for new treatments led to one of the most significant developments in cannabinoid medicine. Epidiolex (cannabidiol/CBD) became the first cannabis-derived medication approved by the FDA, specifically for severe childhood epilepsy syndromes. This approval, based on rigorous clinical trials, marked a turning point in cannabis legitimacy in medicine.
CBD's anti-seizure mechanisms are complex and not fully understood. Unlike THC, CBD doesn't primarily work through cannabinoid receptors. Instead, it appears to modulate ion channels, reduce neuronal hyperexcitability, and have neuroprotective effects. CBD may enhance the effects of the brain's natural inhibitory systems while reducing excessive excitation that leads to seizures. It also has anti-inflammatory effects that may be relevant, as inflammation can contribute to some epilepsy syndromes. THC's role in epilepsy is less clear and potentially problematic. While some patients report benefit from whole-plant cannabis (containing THC), THC can also lower seizure threshold in some individuals. This is why Epidiolex is pure CBD, and why CBD-dominant products are generally recommended for epilepsy.
Note: This information summarizes research findings and is not medical advice. Consult a healthcare provider before using cannabis for any medical condition.
Based on our analysis of peer-reviewed studies on cannabis and epilepsy:
Based on research, these cannabinoids show the most promise for epilepsy:
CBD has the strongest evidence for epilepsy and is FDA-approved. Epidiolex provides pharmaceutical-grade CBD with consistent dosing. Non-pharmaceutical CBD products vary in quality—choose carefully.
Some patients report better seizure control with whole-plant cannabis than CBD alone. The "entourage effect" may play a role. However, THC can also trigger seizures in some people—use cautiously and under medical supervision.
THC alone is generally NOT recommended for epilepsy. It may lower seizure threshold in some patients. Any THC use for epilepsy should be carefully monitored by a neurologist.
Individual responses vary. Work with a healthcare provider to determine the best approach for your situation.
Epidiolex is dosed at 2.5-10 mg/kg twice daily, with most patients using 5 mg/kg twice daily. For a 150-pound adult, this equals about 340mg CBD twice daily (680mg total)—much higher than typical wellness CBD doses. If using non-pharmaceutical CBD, quality and consistency matter enormously. Third-party tested products with verified CBD content are essential. Start lower than pharmaceutical dosing and increase gradually while monitoring seizure frequency. CBD interacts with many anti-seizure medications. It can increase blood levels of clobazam, valproate, and other drugs, potentially increasing side effects. Medication adjustments are often needed. Work with a neurologist experienced in cannabinoid therapy. Epilepsy is serious, and self-treating with unverified products is risky.
Dosing information is based on clinical research and is for educational purposes only. Optimal dosing varies by individual, product formulation, and administration method. Always start with the lowest effective dose and titrate slowly under medical supervision.
When considering cannabis for epilepsy, be aware of these potential concerns:
Discuss these considerations with your healthcare provider before starting cannabis therapy.
A landmark New England Journal of Medicine trial found CBD reduced seizures by 39% (vs 13% placebo) in Dravet syndrome. This led to FDA approval of Epidiolex, the first cannabis-derived medication approved by the FDA.
Source: Devinsky et al., NEJM, 2017 (PMID: 28538134)
Epidiolex (cannabidiol) was FDA-approved in 2018 for Dravet syndrome, Lennox-Gastaut syndrome, and later tuberous sclerosis complex. It's available by prescription and represents the first FDA-approved cannabis-derived medication.
Source: FDA approval, June 2018
Epidiolex uses 5-10 mg/kg twice daily—for a 150-pound adult, this equals 340-680mg CBD twice daily. These are much higher doses than typical CBD products. Non-pharmaceutical CBD quality varies significantly.
Source: Epidiolex prescribing information
CBD (not THC) has the strongest evidence. THC can lower seizure threshold in some patients. Epidiolex is pure CBD. Some patients report benefit from whole-plant cannabis, but use THC cautiously and under neurologist supervision.
Source: Multiple clinical trials and expert consensus
Common questions about cannabis for epilepsy:
Cannabinoids used for medical purposes in children and adolescents were associated with an increased risk of adverse events, including 3x higher withdrawal rates due to adverse events and nearly 2x higher serious adverse events compared to controls.
This comprehensive umbrella review of 101 meta-analyses found high-certainty evidence that CBD effectively reduces seizures in epilepsy, and cannabis-based medicines help chronic pain (30% pain reduction), MS spasticity, and IBD—but also identified clear risks during pregnancy, for mental health, and while driving.
Cannabinoids are effective therapeutics for several medical indications if their specific pharmacological properties are considered. Different cannabinoids have different evidence levels for different conditions.
Cannabidiol significantly reduced TSC-associated seizures compared with placebo. The 25-mg/kg/day dosage had a better safety profile than the 50-mg/kg/day dosage.
Serious adverse effects related to CBD in RCTs are rare and include mainly elevated transaminases, convulsion, sedation, lethargy, and upper respiratory tract infections. These are related to drug-drug interactions with valproate and clobazam.
Long-term CBD treatment had an acceptable safety profile and led to sustained, clinically meaningful reductions in seizure frequency in patients with treatment-resistant Dravet syndrome.
Long-term add-on CBD treatment had an acceptable safety profile in patients with LGS and led to sustained reductions in seizures.
Children and adults with Lennox-Gastaut syndrome experienced 42% reduction in drop seizures with CBD (20mg/kg/day) compared to 17% with placebo, contributing to FDA approval of Epidiolex.
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.
Our reviews are just a starting point. Browse thousands more studies on PubMed for epilepsy.
Epilepsy or seizure disorders qualify in virtually all medical marijuana states. Many states specify "intractable" or "treatment-resistant" epilepsy. Epidiolex is also available as a scheduled prescription without requiring medical marijuana registration.
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.
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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.
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