The Effects of CBD Oil on Epileptic Seizures 


Note: This article is a summarization of scientific research conducted on the efficacy and safety of CBD oil in the treatment of epileptic seizures. The article is solely for informational purposes and is not meant to be used as medical advice. 


For years users of Cannabidiol (CBD oil) knew of its benefits. CBD shows promise for a variety of ailments, including seizures, schizophrenia, gout, rheumatism, malaria, pain, and fever. Due to a lack of research studies and the negative association with marijuana, the medical field ignored CBD oil as a treatment. Interestingly enough, a study on marijuana users helped to establish a link between Cannabis and its powers to treat epileptic seizures. Much has changed in recent years. The legalization of marijuana in the United States and what was once perceived as “anecdotal” effects of CBD oil are being observed by the medical field, forcing them to conduct scientific research on CBD products, establishing efficacy and safety for the product. 


Five Years Back 

Five years ago researchers didn’t have much to go by when it came to CBD oil and epileptic seizures. Researchers knew about Cannabidiol’s effects on the G protein-coupled receptors which respond to a range of substances, including light, hormones, and lipids. Even at low concentrations, CBD decreases G-protein activity. CBD targets transient receptor potential channels which regulate the flow of ions, in this case calcium, creating sensation or perception in the body (1). 

Animal models held some promise, showing anticonvulsant effects of CBD Oil. Even greater results occurred when coupled with antiepileptic drugs phenytoin or phenobarbital. The effects decreased with chlordiazepoxide, clonazepam, trimethadione, and thosuimide. CBD had a pronounced effect on the seizures, but did not have a significant effect on reducing the total number of seizures per animal (1). Several human studies corroborated these findings, stating there were no meaningful changes in seizure frequency. These studies were all hampered by design flaws making their data inaccurate. Properly thought out, unbiased studies are crucial. In this case, improper studies prevented a beneficial treatment from being available for decades. 

Contrary to the other reports, in a small, human study, 8 people received CBD oil or a placebo. Four of the epilepsy patients were “almost free of convulsive crisis” for the duration of the study, three had a partial reduction of their seizures, and one had no response. Importantly, only one person in the placebo group experienced any improvement (1). These studies lacked the proper control and quality to make conclusions on efficacy. They did conclude CBD oil safe, having no severe adverse reactions from quantities of 200-300 mg. Quantities up to 600 mg were well tolerated and would not result in psychotic symptoms. Although these amounts are safe, later we will see in treatment of epileptic seizures doses of 10 mg & 20 mg are the most effective (4). 

Given the data researchers in the article concluded, “There may be a role for CBD in the treatment of epileptic seizures, but well-controlled clinical trials, along with reliable, and standardized CBD products are required.” (1) The authors urged further clinical research, and that is exactly what happened. 


A Lot Can Change in Five Years 

Over the next five years, scientific understanding of CBD oil significantly improved. Brought on by a push from the public and politicians who were seeing the positive effects of CBD oil on patients with epilepsy and schizophrenia. A series of studies published since 2015, reversed the misunderstanding of CBD oil. New information continues to emerge yearly.

Three major studies (2,3,4) played a vital role in the 2018 decision to legalize CBD oil. Though they only indicated CBD for seizures associated with Lennox-Gastaut syndrome and Dravet syndrome. Further studies should be conducted to show the safety and effectiveness of CBD oil on the wide range of conditions which it has shown to improve. These studies would allow for CBD to be indicated for additional treatments.

All three studies since 2015 were conducted in concurrence with antiepileptic drugs. Two were double-blind placebo-controlled trails (2&4), and one trial was open-label (3). All patients had treatment-resistant epilepsy, which means the six drugs meant to help relieve epileptic seizures have little or no effect on these patients. The results observed in these studies may be even greater in those patients whose seizures are not treatment-resistant. 

What did the research discover? 

In the open-label trial (3) (both researchers and participants know which treatment is being administered) which included patients with Lennox-Gastaut syndrome, Dravet syndrome, and other forms of epilepsy, researchers established a baseline for the number of seizures. Two groups received doses of 2-5mg CBD, increasing to 25 mg or 50 mg depending on their group. 

The study found a baseline of 30 monthly seizures which dropped to 15.8, a 47% drop in seizures (3). Being a non-controlled study, the placebo effect was not taken into account. Placebo effect is when someone heals simply by believing that what they are taking will have an effect. This is why it is the gold-standard to have a placebo. If your product performs better than the placebo in efficacy and safety, then you know you have a product that works. 

One concern researchers observed were the number of serious adverse events. Of the 79% who experience adverse events, researchers considered 30% serious, and half of these could have been CBD related (3). With no placebo control, it was impossible to make safety conclusions. 

Although a step in the right direction, the study still contained many shortcomings. The authors determined there were meaningful reductions in seizure frequency, and still determined the safety profile to be adequate despite the number of severe reactions (3). Two later studies would use stronger science, eliminating doubt surrounding CBD oil. 

Two of the most important studies on CBD and epileptic seizures (2&4) were published in 2018. Both were double-blind, placebo-controlled studies (neither doctor nor patient knows which treatment they are receiving/giving, and there was a placebo group, a group which receives an inert substance like a sugar pill). Both studies examined Lennox-Gastaut syndrome. Amounts of CBD were 10 mg or 20 mg. Results in both studies were similar and conclusive. There was a 41.9-43.9% reduction in drop seizures within the 20 mg groups, a 37.2% drop in the 10 mg group, and between 17.2-21.8% drop in the placebo groups. Equally important, 25% of the 20 mg group experienced a 75% reduction in seizures, 39% experienced 50% reduction, and 5 were free of seizures after day 15 to the end of the study (2&4). 

There was a slightly larger rate of mild and moderate adverse events in the CBD group over the placebo. A majority of these events were in the 20 mg group. Events linked to CBD include, appetite reduction, somnolence (a strong desire for sleep), diarrhea, infections, and rash. 14 severe reactions occurred which included elevated aminotransferase levels (ATL) (2). ATL are the levels associated with liver disease and damage. These patients were withdrawn from the study and no actual liver damage occurred. Elevated ATL levels primarily occur within the first 1-2 months of CBD usage. 

In every study conducted, whether following proper study etiquette or not, the addition of CBD oil has a direct correlation the drop in seizures by at least 1/3 over the placebo. The use of CBD in conjunction with antiepileptic drugs had mild side effects but is safe, especially when considering the effects it has on seizures. These are people experiencing up to a median of 85 drop seizures a month, they are taking multiple antiepileptic drugs at a time with little or no effect. With the simple addition of CBD that number dropped to 20, and in a small percentage, the seizures ceased. 


A few thoughts 

Now that we have the proof advocates have sought for decades on epileptic seizures, the public perception of CBD is changing. Still, a variety of questions come to mind and I can’t help but want more information. What does CBD do for epileptic seizures that are not treatment resistant? Is it CBD oil used synchronously with the antiepileptic drugs that causes the drop in epileptic seizures or is it CBD alone? We know that mixing drugs can cause unseen and severe adverse events. Are the adverse events attributed to CBD in these studies due to the mixing of drugs or solely due to CBD? What, if any science is there to back up the claims of CBD helping schizophrenia, rheumatism, and other illnesses? 

There is a great future ahead for CBD, in five years research advances caused a domino effect. New studies are sure to come, backing the known uses of CBD, and hemp. New uses will potentially be discovered in the process. Cannabidiol is a product with unbelievable benefits, which science has shown to be believable. 


Sources and Studies 

  1. Welty TE, Luebke A, Gidal BE. Cannabidiol: promise and pitfalls. Epilepsy Curr. 2014;14(5):250–252. doi:10.5698/1535-7597-14.5.250 
  2. Thiele E, Marsh E, French J, Mazurkiewicz-Beldzinska M, Bendabdis S, Joshi C, et al. Cannabidiol in patients with seizures associated with Lennox-Gastaut syndrome (GWPCARE4): a randomised, double-blind, placebo-controlled phase 3 trial. The Lancet. 2018; Volume 391, Issue 10125, P1085-1096 
  3. Devinsky O, Marsh E, Friedman D, Thiele E, et al. Cannabidiol in patients with treatment-resistant epilepsy: an open-label interventional trial. The Lancet Neurology. 2016; Volume 15, Issue 3: P270-278 
  4. Devinksy O, Patel AD, Cross JH, Villanueva V, Wirrell EC, Privitera M, Greenwood SM, Roberts C, Checketts D, VanLandingham KE, Zuberi SM, GWPCARE3 Study Group. Effect of Cannabidiol on Drop Seizures in the Lennox-Gastaut Syndrome. New England Journey of Medicine. 2018; 378(20), 1888-1897


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About the Author

I graduated from the University of Nebraska with a Bachelor of Landscape Architecture, Bachelor of Design, and a minor in Community and Regional Planning. I've gained valuable experience on researching, also, writing in clear, concise, and active voice. I've been a Landscape Architect for 5 years, where attention to detail is crucial through the design process.