Long-term cannabidiol use for seizures in TSC
About this study
This study examined how Epidyolex, a purified pharmaceutical grade formulation of Cannabidiol (CBD), works over the long term for people with treatment-resistant focal epilepsy. Focal epilepsy is when seizures begin in one part of the brain. The research included people with TSC, as well as people with other forms of focal epilepsy.
How the study was conducted
The research was part of an Expanded Access Program, which provided CBD to people whose seizures did not respond to other anti-seizure medicines. A total of 148 people were followed, including 33 people with TSC, ranging in age from 2 years to 73 years.
Participants took CBD daily, usually around 23-25mg/kg of body weight, and in some cases, higher doses. The study tracked seizure frequency for almost three years and monitored side effects for nearly five years.
Outcomes of the study
CBD treatment led to meaningful reductions in seizure frequency. For people with TSC, focal seizures fell by between 51% – 87% and total seizures by between 44% -87%. For those with other focal epilepsies, reductions were similar.
Most people experienced some side effects, the most common being diarrhoea, drowsiness and reduced appetite. A small number experienced liver-related problems, and about 8% of the total study group stopped taking CBD because of side effects.
Conclusions of the study
The study found that CBD provided sustained reductions in seizures for people with TSC (and for those with other types of focal epilepsy). The safety profile of CBD was consistent with earlier research, and no new safety concerns were identified. Importantly, the results showed similar benefits whether people had TSC or another focal epilepsy.
Implications of the study
For people with TSC-associated epilepsy, this research adds to the long-term evidence that CBD can be effective when other medicines have failed. Although side effects were common, they were usually manageable, and the benefits for many people outweighed the risks. These results suggest that CBD has a useful role in managing seizures across a range of epilepsies, including TSC-related and highlights the importance of further trials to confirm its effectiveness.
DISCLAIMER
This information is intended to provide some insights into recent TSC-related research. It is not intended to, and it should not, constitute medical or other advice. Readers are warned not to take any action without first seeking medical advice.
Patel AD, Szaflarski JP, Lyons PD, Boffa M, Greco T, Saurer TB, Rajasekaran K, Simontacchi KC, Thiele EA. Long-term efficacy and safety of cannabidiol in patients with treatment-resistant focal epilepsies treated in the Expanded Access Program. Epilepsia. 2025 Jul 17. doi: 10.1111/epi.18496. Epub ahead of print. PMID: 40673944.
The full paper can be accessed at: https://doi.org/10.1111/epi.18496