Can Cannabis Treat Epilepsy?

November 2021 by Sandy Yanez

Epilepsy refers to a spectrum of chronic neurological disorders in which clusters of neurons in the brain sometimes signal abnormally and cause seizures. Epilepsy disorder currently affects 2.9 million Americans across all age ranges and ethnicities. Although there are many antiepileptic medications currently on the market, about one-third of persons with epilepsy will continue to have seizures even when treated. Research has found CBD can prevent seizures.

Epilepsy is considered a spectrum disorder because of its different causes, different seizure types, its ability to vary in severity and impact from person to person, and its range of co-existing conditions.

Major Types of Seizures

Seizures are classified into two groups.

  1. Generalized seizures affect both sides of the brain.
  • Absence seizures, sometimes called petit mal seizures, can cause rapid blinking or a few seconds of staring into space.
  • Tonic-clonic seizures, also called grand mal seizures, can make a person
    • Cry out
    • Lose consciousness
    • Fall to the ground
    • Have muscle jerks or spasms

       The person may feel tired after a tonic-clonic seizure.

  1. Focal seizures – are located in just one area of the brain. These seizures are also called partial seizures.
  • Simple focal seizures –affect a small part of the brain. These seizures can cause twitching or a change in sensation, such as a strange taste or smell.
  • Complex focal seizures –can make a person with epilepsy confused or dazed. The person will be unable to respond to questions or direction for up to a few minutes.
  • Secondary generalized seizures –begin in one part of the brain but then spread to both sides of the brain. In other words, the person first has a focal seizure, followed by a generalized seizure.

       Seizures may last anywhere from a few seconds to several minutes.

Epilepsy may be comprised of multiple disorders caused by varied etiologies, including genetic syndromes, stroke, infection, and traumatic brain injury. Many patients with epilepsy also have sensorimotor, cognitive, psychological, psychiatric, and social impairments, as well as impaired quality of life and an increased risk of premature death. While epilepsy can affect patients of all ages, it most commonly affects children, the elderly, and individuals with low socioeconomic status.

The Center of Disease Control (CDC) reports one in 26 people in the USA will develop epilepsy in their lifetime.

The majority of epileptic seizures originate in an area of the brain called the hippocampus, which plays a crucial role in short-term memory, learning, and spatial orientation. Its ability to quickly adopt new neuronal firing patterns renders it especially vulnerable to glitches that initiate seizures.


Can Cannabis Treat Epileptic Seizures?

Both THC and CBD are in a group of substances called cannabinoids. They bind to receptors in the brain and are effective against pain associated with conditions like multiple sclerosis and HIV/AIDS. By attaching to receptors, they block the transmission of pain signals. CBD binds to more than just pain receptors. It appears to work on other signaling systems within the brain and has protective and anti-inflammatory properties.

Exactly how it works in epilepsy isn’t fully understood. But there have been studies that show results with the use of CBD. Studies of mice published in Epilepsia have shown mixed results. While some found CBD was effective against seizures, others needed further research. This may be due to the way the drug was given since some methods work better than others.


CBD and epilepsy

Charlotte Figi, an eight-year-old girl from Colorado with Dravet syndrome, a rare and debilitating form of epilepsy, came into the public eye in 2013 when news broke that medical cannabis was able to do what other drugs could not: dramatically reduce her seizures. Current scientific research provides evidence that cannabis may be an effective treatment for a third of epilepsy patients who, like Charlotte, have a treatment-resistant form of the disease.

Years of research suggest CBD does have benefits for patients who experience epileptic seizures, although the impact is not entirely understood. The US Food and Drug Administration (FDA) approved the first synthetic CBD medication for seizure treatment in 2018.

The cannabis synthetic medication, Epidiolex, was authorized for the treatment of two rare forms of epilepsy: Lennox-Gastaut syndrome and Dravet syndrome.

In 2017, The Lancet Neurology published the results from one of the largest non-synthetic cannabis-based studies for treatment-resistant epilepsy ever conducted. The researchers treated 162 patients with an extract of 99% CBD, a non-psychoactive chemical in cannabis, along with their traditional medication, and monitored them for 12 weeks. The results reported a reduction in motor seizures by 36.5%, with 2% becoming completely seizure free.

Another study from 2015 revealed that 47% of patients whose families had moved to Colorado for cannabis-based epilepsy treatment reported improvement.

THC and epilepsy

To understand how THC works with epilepsy, we need to take a deeper look. In a 2021 study, researchers found epileptic seizures trigger the rapid synthesis and release of a substance by cannabis’s most psychoactive component, THC. This substance is called 2-AG (2-arachidonoylglycerol) and has the beneficial effect of damping down seizure intensity.

2-AG is involved in the regulation of neuronal, immune, metabolic, vascular, and reproductive functions.

Why is this important? 2-AG, when broken down, converts to arachidonic acid, a building block for inflammatory compounds called prostaglandins. Research found the increased prostaglandin causes constriction of tiny blood vessels in the brain where the seizure has originated, cutting off the oxygen supply to the area affected. This oxygen deprivation is known to produce the cognitive deficits of disorientation and memory loss that occurs after a seizure.

Current research is concluding whether CBD can block the breakdown of 2-AG. If this proves to be accurate, THC and CBD, taken together, maybe the answer to drug-resistant epilepsy.


The idea of using the compounds found in cannabis to treat epilepsy is gaining appeal, but currently, there is not enough evidence to form a reliable conclusion. Despite case reports demonstrating efficacy in reducing seizure frequency and severity, limited clinical studies have been published to date.



Devinsky, O., Marsh, E., Friedman, D., Thiele, E., Laux, L., et. al. (2017) Cannabidiol in patients with treatment-resistant epilepsy: An open-label interventional trial. The Lancet Neurology. 15(3),270-278

Devinsky, O., Cilio, M., Cross, H., Fernandez-Ruiz, J., French, C., et. al.(2014) Cannabidiol: Pharmacology and potential therapeutic role in epilepsy and other neuropsychiatric disorders. Epilepsia. 2014; 55(6), 791-802.

Farrell, J. S., Colangeli, R., Dong, A., George, A. G., Addo-Osafo, K., Kingsley, P. J., Morena, M., Wolff, M. D., Dudok, B., He, K., Patrick, T. A., Sharkey, K. A., Patel, S., Marnett, L. J., Hill, M. N., Li, Y., Teskey, G. C., & Soltesz, I. (2021). In vivo endocannabinoid dynamics at the timescale of physiological and pathological neural activity. Neuron, 109(15), 2398–2403.e4.

Farrell, J. S., Colangeli, R., Dudok, B., Wolff, M. D., Nguyen, S. L., Jackson, J., Dickson, C. T., Soltesz, I., & Teskey, G. C. (2020). In vivo assessment of mechanisms underlying the neurovascular basis of postictal amnesia. Scientific reports, 10(1), 14992.

Gaston, T. E., & Szaflarski, J. P. (2018). Cannabis for the Treatment of Epilepsy: an Update. Current neurology and neuroscience reports, 18(11), 73.

Gaxiola-Valdez, I., Singh, S., Perera, T., Sandy, S., Li, E., & Federico, P. (2017). Seizure onset zone localization using postictal hypoperfusion detected by arterial spin labelling MRI. Brain : a journal of neurology, 140(11), 2895–2911.

Kiriakopoulos, E., Shafer, P. (2017) Types of seizures. Epilepsy Foundation. P:March 2017. A:October 10, 2021.

Lerner, R., Post, J., Loch, S., Lutz, B., & Bindila, L. (2017). Targeting brain and peripheral plasticity of the lipidome in acute kainic acid-induced epileptic seizures in mice via quantitative mass spectrometry. Biochimica et biophysica acta. Molecular and cell biology of lipids, 1862(2), 255–267.

Marsicano, G., Goodenough, S., Monory, K., Hermann, H., Eder, M., Cannich, A., Azad, S. C., Cascio, M. G., Gutiérrez, S. O., van der Stelt, M., López-Rodriguez, M. L., Casanova, E., Schütz, G., Zieglgänsberger, W., Di Marzo, V., Behl, C., & Lutz, B. (2003). CB1 cannabinoid receptors and on-demand defense against excitotoxicity. Science (New York, N.Y.), 302(5642), 84–88.

NIH (2015) Epilepsy: Hope through research. NINDS, Publication date April 20105. No. 15-156

Press, C. A., Knupp, K. G., & Chapman, K. E. (2015). Parental reporting of response to oral cannabis extracts for treatment of refractory epilepsy. Epilepsy & behavior : E&B, 45, 49–52.

Rosenberg, E. C., Tsien, R. W., Whalley, B. J., & Devinsky, O. (2015). Cannabinoids and Epilepsy. Neurotherapeutics : the journal of the American Society for Experimental NeuroTherapeutics, 12(4), 747–768.

Shonesy, B. C., Bluett, R. J., Ramikie, T. S., Báldi, R., Hermanson, D. J., Kingsley, P. J., Marnett, L. J., Winder, D. G., Colbran, R. J., & Patel, S. (2014). Genetic disruption of 2-arachidonoylglycerol synthesis reveals a key role for endocannabinoid signaling in anxiety modulation. Cell reports, 9(5), 1644–1653.

Zaheer, S., Kumar, D., Khan, M. T., Giyanwani, P. R., & Kiran, F. (2018). Epilepsy and Cannabis: A Literature Review. Cureus, 10(9), e3278.