CBD Added To Treatment May Lower Hard-To-Control Seizures

What was studied

This paper combined results from 7 randomized, double-blind, placebo-controlled trials of cannabidiol (CBD) used in addition to usual seizure medicines for drug-resistant epilepsy. In total, 1,154 participants were included.

The review included treatment-resistant epilepsies such as Dravet syndrome, Lennox-Gastaut syndrome, and tuberous sclerosis complex. It compared CBD with placebo and also examined whether results differed by CBD dose and by formulation, such as highly purified oral CBD, liposomal CBD, and transdermal CBD.

What they found

Overall, adding CBD reduced seizure frequency compared with placebo. The benefit was reported across the epilepsy syndromes studied. The most favorable results were observed with highly purified oral CBD at 20 mg/kg per day. Liposomal CBD showed modest benefit, and transdermal CBD did not show short-term efficacy in the trials included.

Adverse events were mostly mild and overall were comparable to placebo, but somnolence and elevations in liver enzymes were more frequent in people also taking clobazam or valproate.

Limits of the evidence

This was a meta-analysis, so it depends on the quality and similarity of the trials it included. Only 7 trials were included, and the abstract does not provide details about treatment duration, subgroup sizes, or how seizure outcomes were measured in each study.

The results mainly apply to the specific syndromes and CBD formulations studied, especially purified oral CBD. The study does not show that all CBD products perform similarly, and it does not answer long-term questions about safety, optimal dosing, or how alternative formulations perform over time.

For families and caregivers

For families, this suggests that oral CBD used alongside other seizure medicines may help reduce seizures in some people with certain drug-resistant epilepsies. The evidence in this review was strongest for highly purified oral CBD, not for all over-the-counter CBD products.

It also highlights the need to watch for possible medicine interactions, especially with valproate or clobazam, because liver test changes and sleepiness were more frequent in those situations.

What to watch next

Important next steps include longer-term studies, better evaluation of optimal dosing, and more research on different CBD formulations and tolerability over time.

Terms in this summary

adjunctive therapy

a treatment used in addition to a person's usual medicine

drug-resistant epilepsy

epilepsy that does not come under good control after trying standard seizure medicines

meta-analysis

a study that combines results from several studies to look for overall patterns

randomized, double-blind, placebo-controlled trial

a study where people are assigned by chance to treatment or placebo, and neither patients nor researchers know who gets which during the study

formulation

the form a medicine comes in, such as oral liquid, liposomal product, or skin patch

hepatic enzymes

liver blood test markers that can rise when the liver is irritated or stressed

somnolence

unusual sleepiness or drowsiness