Medical Cannabis in the Treatment of Epilepsy

"We synthesised available evidence on the safety and efficacy of cannabinoids as an adjunctive treatment to conventional AEDs [Anti Epileptic Drugs] in treating drug-resistant epilepsy. In many cases, there was qualitative evidence that cannabinoids reduced seizure frequency in some patients, improved other aspects of the patients’ quality of life and were generally well tolerated with mild-to-moderate AEs [Adverse Events]. We can be much more confident about this statement in the case of children than adults, because the recent, larger, well-conducted RCTs [Randomized Controlled Trials] were performed in children and adolescents.

"In studies where there was greater experimental control over the type and dosage of cannabinoid used, there was evidence that adjuvant use of CBD [cannibidiol] reduced the frequency of seizures, particularly in treatment-resistant children and adolescents, and that patients were more likely to achieve complete seizure freedom. There was a suggestion that the benefits of adding CBD may be greater when patients were also using clobazam.11 12 However because clobazam and CBD are both metabolised in the cytochrome P450 pathway, the pharmacokinetic interactions of these two drugs still need to be fully determined.56 Further randomised, double-blind studies with a placebo or active control are needed to strengthen this conclusion.

"Non-RCT evidence was consistent with RCT evidence that suggested cannabinoids may reduce the frequency of seizures. In most of these studies, cannabinoid products and dosages were less well-controlled, and outcomes were based on self-report (often by parents). These studies provide lower quality evidence compared with RCTs due to the potential for selection bias in the study populations, and other weaknesses in study design. There was also some evidence that studies at very high risk of bias had higher reported proportions of participants reporting reductions in seizures and lower proportions reporting AEs. In RCTs, and most of the non-RCTs, cannabinoids were used as an adjunctive therapy rather than as a standalone intervention, so at present there is little evidence to support any recommendation that cannabinoids can be recommended as a replacement for current standard AEDs."


Stockings E, Zagic D, Campbell G, et al. Evidence for cannabis and cannabinoids for epilepsy: a systematic review of controlled and observational evidence. J Neurol Neurosurg Psychiatry 2018;89:741-753.