Cannabis & Chronic Seizures

Turning the hope of seizure control and safety into a reality

Epilepsy and Seizures

Epilepsy is a central nervous system (CNS) disorder in which nerve cell activity in the brain becomes disrupted, causing seizures or periods of unusual behavior, sensations, and sometimes loss of consciousness. A seizure is a sudden surge of electrical activity in the brain that usually affects how a person appears or acts for a short time.

Seizures can significantly disrupt daily activities of life. Sometimes seizures are not controlled even when treated with multiple anti-seizure medications or surgery. These chronic seizure disorders may be described as “uncontrolled,” “intractable,” “refractory,” or “drug-resistant” epilepsy. Approximately one-third of patients with epilepsy suffer from uncontrolled or refractory epilepsy. For these patients, medical cannabis can be a good option for improving seizure control.


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A New Treatment Option

How Can Medical Cannabis Help With Epilepsy?

Medical cannabis and cannabinoids have shown promise in the treatment of certain forms of epilepsy.

Therapeutic Potential:

  • Medical cannabis has shown potential to significantly reduce the frequency, duration, and intensity of seizures in patients suffering from epilepsy.

  • Cannabidiol (CBD) is the most abundant non-psychoactive cannabinoid found in the Cannabis plant, and cannabidiol-enriched cannabis extracts continue to be used and evaluated for their anti-seizure effects.

  • 1 of every 3 patients with epilepsy has uncontrolled seizures despite treatment with currently-available therapies.

  • Medical cannabis offers a new therapeutic option when current therapies fall short.

The U.S. Food and Drug Administration has not approved Cannabis or cannabinoids for use in treating epilepsy. However, the state of Florida allows patients suffering from chronic seizures access to medical cannabis for symptom relief.

Medical Cannabis: A New Therapeutic Option for Patients in Florida

Patients with uncontrolled epilepsy need access to new treatments that better control seizures and have fewer side effects. Cannabis-based treatment for epilepsy has been associated with significant reductions in the frequency, duration, and intensity of seizures in both children and adults.   Cannabis was used in treating epilepsy as early as the 1800s. Current evidence suggests that the active compounds found in the Cannabis plant have efficacy against seizures.

The specific mechanism of action that results in the anti-seizure effects of cannabinoids is still being defined. Cannabidiol has been shown to stabilize glutamate, an important neurotransmitter in the brain and central nervous system. This reduces inflammation and oxidative stress, two major factors that play a role in seizure disorders. CBD may also preserve the structure and function of nerve cells within the brain.

Cannabidiol (CBD) is the most abundant non-psychoactive cannabinoid and has shown anti-seizure effects, as well as antioxidant and anti-inflammatory effects. In several animal models of seizures, CBD has demonstrated anti-seizure effects. Initial data from studies in small numbers of patients suggest that CBD may be effective in the treatment of some patients with epilepsy.

Clinical data supporting the efficacy and safety of CBD in the treatment of epilepsy are limited, yet promising, both in adults and children who are suffering from refractory epilepsy.

The American Epilepsy Society (AES): Medical Cannabis is Promising, But Not Yet Proven

The AES is a medical and scientific society whose members are engaged in research and clinical care for people with epilepsy. Based on the evidence available today, the AES has taken the following position on medical cannabis: “The anecdotal reports of positive effects of the marijuana derivative cannabidiol (CBD) for some individuals with treatment-resistant epilepsy give reason for hope. However, we must remember that anecdotal reports alone are not sufficient to support treatment decisions…AES urges all people touched by epilepsy to consult with an epilepsy specialist and explore the many existing treatment options, so that they can make informed decisions with their specialist that weighs the risks and benefits of the different treatment options.”

Source: The American Epilepsy Society Position Statements

Consult with an epilepsy healthcare provider about medical cannabis and whether it is right for you or your loved one.

Parents: More Control with Medical Cannabis

What Do Parents of Children with Epilepsy Have to Say About Treatment with Medical Cannabis?

Numerous patients, caregivers, and physicians have reported a significant reduction in seizure frequency with medical cannabis therapy. The results of two distinct parent surveys have been published in the medical literature and are shared below. These results share the experiences of 94 children who were treated with medical cannabis for the following conditions: Dravet syndrome, Doose syndrome, Lennox-Gastaut syndrome, and idiopathic epilepsy.

Report on Parent Surveys

Report of a Parent Survey of Cannabidiol-Enriched Cannabis Use in Pediatric Treatment-Resistant Epilepsy:

A 2013 survey of caregivers of 19 children with severe epilepsy who were receiving cannabidiol-enriched cannabis extracts indicated that 2 of the children had become seizure-free and 8 others had a reduction in the frequency of seizures of 80% after taking the extract:

"Sixteen (84%) of the 19 parents reported a reduction in their child’s seizure frequency while taking cannabidiol-enriched canabis. Of these, two (11%) reported complete seizure freedom, eight (42%) reported a greater than 80% reduction in seizure frequency, and six (32%) reported a 25-60% seizure reduction. Other beneficial effects included increased alertness, better mood and improved sleep."


Report of a parent survey of cannabidiol-enriched cannabis use in pediatric treatment-resistant epilepsy. Brenda E. Porter and Catherine Jacobson. Epilepsy Behav. 2013 Dec; 29(3): 574–577.

Parental Reporting of Response to Oral Cannabis Extracts for Treatment of Refractory Epilepsy:

In a 2015 survey of 75 parents whose children were treated with oral cannabis extracts in Colorado, the parents reported that one third of the children had a reduction in seizures of more than 50%.

"Seventy-five patients were identified of which 57% reported any improvement in seizure control and 33% reported a >50% reduction in seizures (responders). If the family had moved to CO for OCE treatment, the responder rate was 47% vs. 22% for children who already were in CO. The responder rate varied based on epilepsy syndrome: Dravet 23%, Doose 0%, and Lennox-Gastaut syndrome (LGS) 88.9%. The background EEG of the 8 responders where EEG data were available was not improved. Additional benefits reported included: improved behavior/alertness (33%), improved language (10%), and improved motor skills (10%)."


Parental reporting of response to oral cannabis extracts for treatment of refractory epilepsy. Press CA, Knupp KG, Chapman KE. Epilepsy Behav 2015; 45: 49-52.

Spotlight on Research

Selected Studies and Publications for Cannabis & Chronic Seizures

To formally evaluate how effective a therapeutic agent is, doctors and researchers study how it performs in well-designed clinical studies in the treatment of specific medical conditions across defined populations of patients. We’ve highlighted a few key studies below that demonstrate the potential of medical cannabis in the treatment of epilepsy and also provided links to a couple review articles that summarize the results of important human studies in this field.

Despite the promising studies in animals and numerous patient reports on the effectiveness of cannabis in the treatment of epilepsy, recent reviews of available literature point to the lack of well-designed, prospective clinical studies of medical cannabis in epilepsy. A recent Cochrane review concluded that “no reliable conclusions can be drawn at present regarding the efficacy of cannabinoids as a treatment for epilepsy” due to the lack of adequate data from randomized, controlled trials of cannabinoids. This assessment was confirmed in a recent review of available data by the American Academy of Neurology. Due in part to governmental regulations that have hindered medical cannabis research, few studies in humans have been performed to date that involve the isolated use of cannabinoids to treat epilepsy.

Review Articles

Cochrane Review

Four randomized controlled trial reports that included a total of 48 patients, each of which used cannabidiol as the treatment agent. One report was an abstract and another was a letter to the editor. Anti-epileptic drugs were continued in all studies. Details of randomization were not included in any study report. There was no investigation of whether the control and treatment participant groups were the same or different. All the reports were low quality. The four reports only answered the secondary outcome about adverse effects. None of the patients in the treatment groups suffered adverse effects. All the studies were considerably underpowered and had methodologic problems, including the lack of blinding. Two studies showed a reduction in the number of seizures in patients treated with cannabidiol, whereas the other two studies showed no effect.

No reliable conclusions can be drawn at present regarding the efficacy of cannabinoids as a treatment for epilepsy. The dose of 200 to 300 mg daily of cannabidiol was safely administered to small numbers of patients generally for short periods of time, and so the safety of long term cannabidiol treatment cannot be reliably assessed.


Gloss D, Vickrey B. Cannabinoids for epilepsy. Cochrane Database Syst Rev 2014; 3: CD009270.

Cochrane Database Syst Rev. 2014 Mar 5;(3):CD009270. doi:10.1002/14651858.CD009270.pub3.

Recent clinical studies of oral cannabidiol (CBD) extract:

1)  Since 2013, a consortium of 10 epilepsy centers has been collecting prospective data on children and young adults with severe epilepsy who are receiving Epidiolex, a purified cannabis extract containing 99% cannabidiol and less than 0.10% Δ9-THC (GW Pharmaceuticals), through an expanded-access program authorized by the Food and Drug Administration (FDA). A preliminary report from this open-label study, initiated by investigators to assess the safety and dosing of cannabidiol, noted that among 137 patients who had received at least 12 weeks of treatment, the median reduction in the number of seizures was 54%.41 Randomized clinical trials of Epidiolex are now being conducted for the treatment of two forms of severe, childhood onset epilepsy: Dravet’s syndrome (a severe myoclonic epilepsy of infancy) (NCT02091375) and the Lennox–Gastaut syndrome (a childhood-onset, treatment-resistant epilepsy characterized by multiple types of seizures and developmental delay) (NCT02224690).


2)  In December 2015, an open-label study of an oral cannabidiol (CBD) product (Epidiolex®) showed significantly reduced seizure frequency in children and young adults with multiple forms of drug-resistant epilepsy, including Dravet Syndrome and Lennox-Gastaut Syndrome.  CBD was added to existing anti-epileptic treatment regimens. The study took place at over 11 epilepsy centers across the United States, and included 162 patients in the safety and tolerability analysis and 137 patients in the efficacy analysis.  The results showed a median 36.5% reduction in monthly motor seizures.  Over 12 weeks, the median monthly frequency of motor seizure fell from 30.0 to 15.8.  Overall, CBD was shown to have a sufficient safety profile and was well-tolerated.


News Releases

In March of 2016, GW Pharma announced positive Phase 3 pivotal study results of an oral cannabidiol (CBD) product (Epidiolex®) in 120 children with Dravet Syndrome. In this randomized, placebo-controlled study, the CBD product significantly reduced convulsive seizures over the 14-week treatment period compared with placebo (p=0.01). In this study, patients taking Epidiolex achieved a median reduction in monthly convulsive seizures of 39 percent compared with a reduction on placebo of 13 percent, which was highly statistically significant (p=0.01). Epidiolex was generally well tolerated. The most common adverse events (occurring in greater than ten percent of Epidiolex-treated patients) were: somnolence, diarrhea, decreased appetite, fatigue, pyrexia, vomiting, lethargy, upper respiratory tract infection and convulsion.  Of those patients on Epidiolex that reported an adverse event, 84 percent reported it to be mild or moderate. Ten patients on Epidiolex experienced a serious adverse event compared with three patients on placebo. Eight patients on Epidiolex discontinued treatment due to adverse events compared with one patient on placebo.

Additionally, in June of 2016, GW Pharma announced positive Phase 3 pivotal trial results for Epidiolex®  in the treatment of Lennox-Gastaut Syndrome. We look forward to reviewing these important study results and the full data when they are made public.

Please see the links to the right. Below, you will find ongoing releases from GW Pharmaceuticals:

GW Pharmaceuticals Press Releases