Medical marijuana and the treatment of epilepsy

Cannabis as a helpful medicine for epilepsy first made headlines in 2013 when the family of Charlotte Figi, a young girl from Colorado, claimed marijuana helped their daughter overcome her severe epileptic seizures. Since then, the body of evidence supporting cannabis as an anticonvulsant has only grown.

Could cannabis be the new hope for the thousands of families like the Figis looking for a reliable alternative to regular epilepsy treatment?


Epilepsy refers to a group of chronic neurological disorders that are characterized by producing recurrent, uncontrollable seizures. Epilepsy is believed to affect around 1% of the entire world population.

A seizure, in its most basic sense, is caused by the synchronized, abnormal firing of neurons in the brain. These neurons are responsible for sending information around the brain to ultimately control nerve, muscle, or gland cells in the body.

The excessive and abnormal firing of these neurons essentially interrupts the flow of information in the brain and causes a seizure. Some patients may experience subtle seizures, which cause simple symptoms such as staring, fits of laughter, or hyperventilation. Others, however, may experience more intense seizures, which can include uncontrollable convulsive fits or even lead to a loss of consciousness.

In fact, while we often think of a seizure as a display of outward symptoms such as jerking or convulsing, a seizure can also include subjective symptoms that only the patient notices, such as strange smells or even fears. How these seizures manifest can vary greatly from one patient to another and largely depends on which part of the brain is affected.


Epileptic seizures are broken down by the part of the brain, which they affect, and their individual symptoms.

Focal seizures (also known as partial seizures) are caused by a neurological episode affecting specific parts of the brain (such as a single hemisphere or lobe). They can usually be broken down further into the following categories:

  • Simple focal seizures: Usually affect a small part of the brain. The patient is conscious and can experience subjective symptoms (like sensing strange smells or tastes) or outward symptoms like jerking which starts in a small part of the body and gradually affects more muscle groups.
  • Complex focal seizures: Similar to simple focal seizures but are accompanied by impaired alertness or responsiveness or even a complete loss of consciousness altogether.

Generalized seizures, unlike focal seizures, tend to affect both hemispheres of the brain. Some seizures can start off as partial seizures before quickly developing into generalized seizures as more parts of the brain become affected.

Generalized seizures, like focal seizures, can be broken down into multiple categories:

  • Tonic generalized seizures: Characterized by causing stiff or flexed muscles, often causing a patient to fall over backwards.
  • Atonic seizures: Characterized by causing relaxed, floppy muscles that often cause a patient to fall forwards.
  • Clonic seizures: Cause violent physical contractions known as convulsions. Clonic seizures are often preceded by a short tonic period, at which stage they become tonic-clonic seizures.
  • Myoclonic seizures: Cause small muscle twitches.
  • Absence seizures: Patients lose and regain consciousness very quickly. Usually the only outward symptom of an absence seizure is looking “spaced out.”

All of these seizures tend to last short amounts of time, usually less than 5 minutes. However, some patients can experience seizures that last longer than this. A seizure that lasts for more than 5 minutes or a a fast onsets of multiple seizures is known as status epilepticus and usually involves tonic-clonic seizures (although not always the case).

Status epilepticus can be life threatening and must be treated urgently.


Apart from the types of seizures discussed above, patients with epilepsy may also experience other symptoms like:

  • Postictal confusion: A state of confusion that usually hits after a seizure has taken place.
  • Todd’s Paralysis: A paralysis of the arms or legs, usually limited to one side of the body. Can take between 15 to 48 hours to wear off completely.
  • Mental health issues: Epileptic patients are at a higher risk of developing mental health problem like anxiety or depression. This can be caused by a difficulty dealing with the disease, side effects caused by medication, or the stigma surrounding the disease in some parts of the world.


The exact causes of epilepsy are unknown. In fact, doctors are unable to find a direct cause of the disease in about 50% of patients. In others, however, the condition may be caused by factors such as:

  • Genetics
  • Head traumas caused by accidents
  • Brain conditions such as tumours or strokes which can cause damage which ultimately causes seizures
  • Some infectious diseases can lead patients to develop epilepsy. These include meningitis, AIDS, and viral encephalitis
  • Prenatal brain damage caused by an infection, poor nutrition, or oxygen deficiencies can cause neurological conditions like epilepsy or cerebral palsy in a child
  • Developmental disorders such as autism and neurofibromatosis can sometimes be associated with epilepsy

A person who experiences seizures will usually undergo brain imaging tests such as MRI and CT scans. These are designed to see if any brain abnormalities such as tumours or clots could be responsible for causing the seizures.

Epilepsy patients also undergo EEG (electroencephalogram) tests which monitor the electrical activity in the brain. These tests are designed to help doctors detect abnormal electrical waves caused by unusual neuron activity and trace them back to specific areas of the brain.

Doctors will also thoroughly investigate a patient's clinical history in order to help them rule out other conditions before diagnosing a patient with epilepsy. Once diagnosed, a patient usually undergoes treatment with a wide variety of anticonvulsants designed to minimize the frequency and severity of seizures.

Some patients may also undergo epilepsy surgery, which involves removing a part of the brain believed to be the cause of seizures. Nerve stimulation, which involves stimulating nerves in the brain to control the release of specific neurotransmitters and ultimately help control neural activity, is also recommended in some patients.


Anticonvulsants are only effective in roughly 30% of epilepsy patients. In fact, many patients need to take multiple different convulsants in order to get some relief from their seizures and often suffer from a wide variety of side effects.

The exact statistics on how many patients experience adverse effects from antiepileptic drugs varies with some sources claiming they can affect up to 90% of patients. Most side-effects can be controlled by adjusting the dosage and are only mild, though they can be severe or chronic as well. Up to 25% of epilepsy patients are believed to drop their treatment due to side effects.

The side effects of anticonvulsant medications include:

  • Mood changes
  • Fatigue or tiredness
  • Rash

Liver damage

  • Birth defects when used during pregnancy
  • Low levels of white blood cells (necessary to fight infection) and platelets (necessary to control bleeding) in the blood
  • Aplastic anemia (serious damage to bone marrow which affects the proper production of blood cells)


A growing number of clinical trials, laboratory studies, and anecdotal reports suggest that certain compounds found in cannabis may help alleviate the severity and frequency of epileptic seizures.

The main cannabinoid thought to have anticonvulsant effects is cannabidiol (or CBD). CBD is a non-psychoactive compound found in high concentrations in hemp as well as unique medical-grade cannabis varieties.

One of the most famous cases highlighting CBD’s anticonvulsant effects is that of Charlotte Figi, a young girl from Colorado suffering from a rare type of epilepsy known as Dravet Syndrome.

After suffering over 400 seizures a week (some of which lasted as long as 30 minutes) and not finding any relief from standard anticonvulsant information, Charlotte’s parents and doctors turned to cannabis for answers.

They began treating Charlotte with a CBD-rich extract (now known as Charlotte’s Web) made by a group of cannabis cultivators in Colorado, USA, known as the Stanley Brothers. In her first week of treatment, Charlotte experienced no seizures at all.

Since Charlotte’s story made international headlines in 2013, thousands of other similar cases have also surfaced in support of CBDs anticonvulsant properties.

Given these many success stories, scientists soon began looking into CBD as an anticonvulsant. One of the major clinical studies looking into CBD was published in 2015 in The Lancet medical journal.

The study involved 214 epileptic patients, some of which suffered from severe manifestations of the disease, such as Dravet or Lennox-Gastaut syndrome. The patients were treated with a 99% CBD extract similar to Charlotte’s Web for 12 weeks, with researchers closely monitoring their response.

The study showed that CBD reduced motor seizures on average by 36.5%, while 2% of patients became completely seizure free. However, it also noted that the CBD extract produced side effects in almost 80% of the patients, including decreased appetite, diarrhea, sleepiness, fatigue, and even convulsions.

Nonetheless, the study’s authors concluded that CBD could potentially alleviate the symptoms of epilepsy while possibly being well tolerated by most patients. However, they also noted that more research into the cannabinoid was needed.

Since the release of this landmark study, numerous other trials have produced positive results regarding cannabis’ ability to reduce the intensity and frequency of seizures caused by epilepsy.

Most notably, a 2017 study published in the The New England Journal of Medicine by the same author as the Lancet trial, once again proved CBDs efficacy as an anticonvulsant. The study was both double-blind and placebo-controlled, making fro the highest standard for medical investigations possible.

The study involved 120 children and teenagers with Dravet syndrome who were split into a test and control (or placebo) group. The test group was treated using Epidiolex, a CBD drug produced by GW Pharmaceuticals, and monitored for a total of 14 weeks.

The results found that the average number of monthly seizures in the CBD group decreased from 12.4 to 5.9 (52%). The placebo groups results dropped from 14.9 to 14.1 (5%). 3 patients in the CBD group were also left completely seizure-free.

Once again, the study noted that over 90% of the patients treated with CBD experienced side-effects, including sleepiness, vomiting, fatigue, decreased appetite, diarrhea and elevated levels of liver enzymes. 8 patients also discontinued the study due to these side effects.

Nonetheless, the authors of the study said they hoped this new evidence help validate the growing body of anecdotal evidence for CBD. Most importantly, they hoped it would help motivate a rescheduling of cannabis (currently schedule 1), given that there is there plenty of evidence in favour of the drug’s medical potential.

Epilepsy is a qualifying medical condition in various US states under their medical marijuana programs. These include:

  • Alaska
  • Arizona
  • Arkansas
  • California
  • Connecticut
  • Delaware
  • Florida
  • Georgia
  • Hawaii
  • Illinois
  • Indiana
  • Iowa
  • Maine
  • Maryland
  • Michigan
  • Minnesota
  • Missouri
  • Montana
  • Nevada
  • New Hampshire
  • New Jersey
  • New Mexico
  • New York
  • North Carolina
  • North Dakota
  • Ohio
  • Oklahoma
  • Oregon
  • Pennsylvania
  • Rhode Island
  • South Carolina
  • Texas
  • Utah
  • Vermont
  • Washington
  • West Virginia
  • Wyoming

Outside of the US, medical cannabis is also available in a variety of other countries, including Australia, Chile, Argentina, Canada, and more. To find our whether epilepsy is a qualifying condition in your area, please consult your local authorities.