Cannabis and Epilepsy: Why the Drug is Getting an FDA First

Last Updated on May 24, 2022 by Mark Conklin, RN, MHA

Epidiolex is the first plant-based drug derived from cannabis and approved for treatment in the US. See what the research says about taking CBD oil for epilepsy now.

THC Physicians Cannabis and Epilepsy

What does the research say about cannabis and epilepsy?

Epilepsy is a neurological disorder in which nerve cell activity in the brain becomes disrupted and causes seizures or periods of unusual behavior, sensations, and sometimes loss of consciousness.

Roughly 30% of patients with epilepsy have a treatment-resistant form that makes their symptoms worse and increases their risk of death.

On June 25, 2018, the US Food & Drug Administration (FDA) approved a drug called Epidiolex® to treat two rare, severe forms of epilepsy: Lennox-Gastaut syndrome and Dravet syndrome, in patients over the age of two.

Epidiolex is an oral solution made of cannabidiol, making it the first plant-based drug derived from cannabis and approved by the FDA in the US [1]. It’s also the first FDA approved medication to treat seizures in those with Dravet syndrome.

This is a milestone in establishing cannabidiol, or CBD, as a safe and effective treatment for epilepsy.

But what is CBD and what does the research on cannabis and epilepsy show?

What Is Cbd Oil And Why Is It Used For Seizures? 

The cannabis plant contains hundreds of compounds called cannabinoids. These cannabinoids act on cannabinoid receptors in the body to produce different therapeutic effects.

The two most studied and discussed cannabinoids are:

  • Tetrahydrocannabinol, or THC, causes psychoactive “high” and mental impairment when using marijuana.
  • Cannabidiol, or CBD, does not have any psychoactive properties and has been studied for its many positive health benefits.
THC Physicians Cannabis and Epilepsy

One of the newly researched health benefits of CBD is seizure reduction.

Though CBD has shown anticonvulsant properties in many animal studies, there’s been limited data in human trials due to marijuana still being illegal at the federal level [2].

With wider marijuana legalization across the country, scientists are learning CBD may provide neuroprotective and anti-inflammatory benefits as well [3].

While the reasons CBD works against seizures aren’t fully understood yet, evidence from clinical trials suggests it may be effective for treatment-resistant epilepsy.

Cannabis and Epilepsy: Scientific Evidence of Epidiolex (Cbd) in Clinical Trials

Epidiolex is a purified CBD extract (>99% CBD) with a known and consistent amount of CBD in each dose.

Researchers in controlled clinical trials of Epidiolex gave participants CBD oil or a placebo in addition to their pre-existing epilepsy medication.

In one study, a total of 225 people were enrolled in three groups taking either:

  • 20mg of CBD oil
  • 10mg of CBD oil
  • No CBD oil

After 14 weeks of twice-daily CBD administration, drop seizures decreased from baseline by [4]:

  • 41.9% in the 20mg CBD group
  • 37.2% in the 10mg CBD group
  • 17.2% in the placebo group

In another study, 214 participants with treatment-resistant epilepsy ranging from the age of two to 26 were given Epidiolex without a placebo control group. After 12 weeks seizures decreased by an average of 54% with the addition of CBD oil [5].

THC Physicians Cannabis and Epilepsy

Finally, researchers in a study of 120 children and young adults with Dravet syndrome and drug-resistant seizures split participants up into groups taking either 20mg of CBD per kilogram of body weight per day or a placebo.

Results after 14 weeks revealed [6]:

  • The frequency of total seizures of all types was significantly reduced with CBD.
  • The median frequency of convulsive seizures per month decreased from 12.4 to 5.9 with CBD. There was only a decrease from 14.9 to 14.1 with the placebo.
  • 43% of participants in the CBD group had at least a 50% reduction in convulsive-seizure frequency compared to just 27% with the placebo.
  • 5% of participants became seizure-free with CBD while 0% were completely free of seizures on the placebo.

Caregivers also reported a 62% improvement in patients in the cannabidiol group whereas only 34% of the placebo group caregivers could say the same.

Though mild side effects were reported by patients in all studies, it wasn’t enough to deter a majority from continuing the CBD trial.

Side Effects of Cbd Oil for Epilepsy and Potential Drug Interactions

The most frequently reported side effects of using CBD oil for epilepsy are drowsiness, loss of appetite, insomnia, and diarrhea.

But patients in trials of Epidiolex most often stopped taking CBD due to changes in their liver function.

CBD is processed in the liver, but it may also prevent the breakdown of other drugs, or increase their concentration of them throughout the body. This means those taking antiepileptic drugs may have more of them in their system with the addition of CBD oil.

Patients on valproic acid (VPA), a commonly used anti-seizure medication, did not have increased levels of the drug though some reported liver enzymes that were three times higher than normal with the addition of CBD oil.

Those on clobazam (Onfi) noticed an interaction that made them more tired after taking CBD oil as well.

THC Physicians Cannabis and Epilepsy

With careful monitoring and few severe side effects, the reported risks of using CBD oil are relatively low for the potential benefits.

Finding the Right Cbd Epilepsy Dosage

According to one study, CBD is well tolerated in most people up to 600 mg per day [7]. And another study showed CBD is well tolerated at extremely high levels in those with epilepsy specifically [8].

However, it should be noted that CBD dosing recommendations still have a long road, specifically as it concerns research and the amounts for the everyday user or those with a serious ailment.

Primary factors influencing CBD oil dosage are:

  • Age
  • Severity of symptoms
  • Weight
  • Tolerance of CBD oil
  • Sex. Due to the presence of additional body fat, females may require a lower dose than males.
  • Potential drug interactions
  • Route of administration. Absorption rates of CBD oil from highest to lowest go: Intravenous > Intramuscular > Subcutaneous > Oral.
  • Time and frequency of dosing

Where Can You Buy Cbd Oil?

Though over half the states in the US have now legalized medical marijuana, cannabis-derived CBD oil (considered to be a form of medical marijuana), in legal states, is only available through a medical marijuana doctor.

The good news is you can buy full-spectrum CBD oil made from hemp, which comes from the same cannabis plant species as marijuana, without visiting a medical marijuana clinic. Since hemp and hemp-derived products are legal in all 50 states, you can buy hemp CBD oil online and in many health food stores across the country.

THC physicians are here to help people in New York and Florida receive the medical treatment they need. If you have any questions about getting a marijuana card, please browse our how-to page for more information or contact us if there is anything we can answer for you!


  1. FDA approves the first drug comprised of an active ingredient derived from marijuana to treat rare, severe forms of epilepsy.
  2. Cannabidiol: pharmacology and potential therapeutic role in epilepsy and other neuropsychiatric disorders.
  3. Multiple mechanisms are involved in the large-spectrum therapeutic potential of cannabidiol in psychiatric disorders.
  4. Effect of Cannabidiol on Drop Seizures in the Lennox–Gastaut Syndrome.
  5. Cannabidiol in patients with treatment-resistant epilepsy: an open-label interventional trial.
  6. Trial of Cannabidiol for Drug-Resistant Seizures in the Dravet Syndrome.
  7. Cannabidiol: Promise and Pitfalls.
  8. An Update on Safety and Side Effects of Cannabidiol: A Review of Clinical Data and Relevant Animal Studies.

Howard Seth Meiselman, DO

Medically reviewed by Howard Seth Meiselman, DO — Written by Mark Conklin 

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Mark Conklin, RN, MHA

Mark Conklin is the founder and CEO of Tierra Healthcare Concepts and is also part of the medical team. He has over 25 years of experience in the healthcare field working at the executive management level and as a medical professional. Education RN, BS Biology, and Master of Health Administration course curriculum.

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