Marijuana for Epilepsy: Weighing the Evidence

Epilepsy Notes

Andrew N. Wilner, MD


March 25, 2014

In This Article

The Clinical Trial Evidence to Date

Cannabinoids may have therapeutic potential in epilepsy, but their efficacy and safety for this indication remain to be proven.[3] GW Pharmaceuticals, which markets a metered-dose marijuana product (Sativex®) for the treatment of spasticity and neuropathic pain in multiple sclerosis and cancer pain (approved outside the United States), recently obtained "orphan drug" designation for Epidiolex™, an oral liquid that contains plant-derived cannabidiol without THC for use in the treatment of Dravet syndrome.[5] The US Food and Drug Administration (FDA) has allowed physicians to treat approximately 125 children with intractable epilepsy with Epidiolex immediately under an "expanded access" program.

Furthermore, a multicenter, international study of Epidiolex has just begun and will enroll a total of 150 patients across 6 centers.[6] Children with intractable epilepsy between the ages of 1 and 18 years are eligible. Participating centers include the University of California San Francisco Pediatric Epilepsy Center, and the New York University Langone Medical Center.

To date, however, the number of clinical trials that demonstrate that marijuana helps control seizures? None.

Evidence for Harm?

Adverse events have been associated with marijuana. For example, early cannabis use may be related to poorer cognitive outcomes, owing to interference with brain development.[7]

An epidemiologic study of 410 patients with first-episode psychosis revealed that those with a history of cannabis use presented with psychosis at a younger age than those who never used cannabis (P < .001).[8] A conclusion of that study was that "daily use, especially of high-potency cannabis, drives the earlier onset of psychosis in cannabis users."

A new problem has emerged with the development of synthetic cannabinoids, known as "spice" or "K2," which can have more than 1000 times the binding strength to cannabis receptors in the brain.[9] Synthetic cannabinoids resulted in 76 emergency department visits in Colorado for altered mental status, seizures, and cardiac toxicity.[8] A synthetic cannabinoid, JWH-018, was recently associated with stroke in 2 siblings.[11] Synthetic cannabinoids are particularly problematic because they do not result in a positive toxicology screen for THC.[12]


Comments on Medscape are moderated and should be professional in tone and on topic. You must declare any conflicts of interest related to your comments and responses. Please see our Commenting Guide for further information. We reserve the right to remove posts at our sole discretion.