At the American Epilepsy Society meeting in Philadelphia, researchers are unveiling the results of trials testing the safety and efficacy of cannabidiol. The findings are largely promising. In the biggest study, the number of seizures went down by about half, on average, among children who completed the trial. Benefits for some continued even after the study was over.

“In the subsequent periods, which are very encouraging, 9 percent of all patients and 13 percent of those with Dravet Syndrome epilepsy were seizure-free,” Dr. Orrin Devinsky, the study’s lead author and a neurologist at the New York University Langone Medical Center, told NPR. “Many have never been seizure-free before.”

The data represent a significant step forward in legitimizing use of cannabis to treat epilepsy, a syndrome that in both children and adults causes debilitating seizures and can be especially difficult to treat. Patients sometimes exhaust traditional anti-seizure medications to no effect.
Despite the findings of CBD’s potential benefit in epilepsy treatment, the study results weren’t all good. In Devinsky’s three-month trial, 16 percent of participants withdrew due to adverse side effects or after deciding the treatment was ineffective. And in a yearlong study of 25 patients, one participant actually experienced more frequent seizures.
Participants in the studies didn’t smoke or vaporize cannabis flowers or concentrates. Rather, they consumed cannabidiol in the form of daily doses of purified extracts that had been derived from cannabis plants.

Parents across the country have turned to high-CBD strains after hearing about their sometimes life-changing benefits. Charlotte’s Web, for example, was developed in 2011 and popularized after it was used successfully to treat epileptic seizures in a Colorado girl, Charlotte Figi. While Figi’s story has encouraged lawmakers in some states to loosen regulations on high-CBD strains, many desperate parents still obtain the drug illegally. And because of a lack of scientific evidence to justify their decision, they often face stigma — not to mention the risk of jail time — for giving their children cannabis.