“Background: Epilepsy affects approximately 70 million people globally, with one-third experiencing drug-resistant epilepsy (DRE). Cannabidiol (CBD) has shown promise in reducing seizure frequency for specific epilepsy syndromes, though data for broader etiologies remain limited. The goal of the study is to evaluate the effectiveness of CBD as an adjunct treatment in the reduction of seizure frequency in DRE patients of various etiologies.

Methods: We conducted a retrospective chart review of patients with refractory epilepsy who received a CBD as an adjunct treatment at two tertiary care centers. Seizure frequency at the start of CBD treatment and at a minimum follow-up of 3 months was recorded. Epilepsy diagnosis was categorized into five groups: Focal/Multifocal Epilepsy, Primary Generalized Epilepsy, Lennox-Gastaut Syndrome, Dravet Syndrome, and Other Developmental and Epileptic Encephalopathies.

Results: Among all patients, 49 % achieved a ≤ 25 % reduction in seizures, while 5 % had a 26-50 % reduction, 21 % reached a 51-75 % reduction, 20 % experienced a 76-99 % reduction, and 5 % achieved near seizure freedom. There was a significant reduction in median seizure frequency from 30 at baseline to 8 post-treatment (p = 0.000). Significant reductions in seizure frequency were also observed within each diagnostic category.

Discussion: CBD has proven to be an effective adjunctive treatment for medically refractory epilepsy, showing significant efficacy across various epilepsy etiologies and genetic backgrounds. Its ability to reduce seizure frequency and the burden of anti-seizure medications (ASMs), especially in syndromes that are traditionally difficult to manage, highlights its value as an additional therapeutic option.”

https://pubmed.ncbi.nlm.nih.gov/40288063/

https://www.epilepsybehavior.com/article/S1525-5050(25)00165-9/abstract

“Objectives: To describe the effectiveness and tolerability of cannabidiol (CBD) in children with drug-resistant epilepsy (DRE).

Methods: Records of children with DRE who received CBD for at least six months were reviewed. Reduction in seizure frequency [complete (> 90%), partial (30-90%), no response (< 30%)], parent reported adverse effects and discontinuation of CBD, if any, were noted.

Results: Records of 50 children with DRE (Lennox-Gastaut syndrome 32, Dravet syndrome 4, and Tuberous sclerosis complex 2), mean (SD) age 7.8 (4.3) years were reviewed. Complete, partial, and no response to CBD was seen in 10, 18 and 14 children; 8 became seizure-free. Eight children discontinued treatment due to lack of efficacy (n = 4), by increased adverse effects (n = 3) and aggravation of seizures (n = 1). Adverse effects were noted in 22 (44%), none required hospitalization.

Conclusion: Cannabidiol is a useful and safe add-on drug in children with DRE.”

https://pubmed.ncbi.nlm.nih.gov/40261499/

https://link.springer.com/article/10.1007/s13312-025-00075-9

“Cannabidiol has shown promising effects on reducing seizure frequency in children and adults with selected epilepsy syndromes. In this narrative brief review, we provide an update on the use of cannabidiol in pediatric epilepsy including the indications for its use, clinical efficacy, adverse effects, requirements for monitoring and regulations.”

https://pubmed.ncbi.nlm.nih.gov/40244307/

https://link.springer.com/article/10.1007/s13312-025-00015-7

“Background: Epilepsy is a neurological syndrome caused by excessive neuronal discharges, with a part of the patients being pharmacoresistant to the traditional treatment. Cannabidiol, a non-psychoactive component of Cannabis Sativa, shows promise as an alternative, but further research is needed to quantify its efficacy.

Methods: This literature systematic review was made following the PRISMA protocol guidelines. The Google Scholar, Scielo, and PubMed/MEDLINE databases were included using the descriptors “Cannabidiol”, “Epilepsy”, and “Drug Resistant Epilepsy”. This research was registered in the Prospero platform with the identification (CRD42024479643).

Results: A total of 1448 results were identified from the PubMed, Virtual Health Library, and Google Scholar databases. After applying exclusion criteria, six studies met the criteria for full-text evaluation and eligibility. The compiled analysis showed that the patients who received cannabidiol experienced a 41.0875% reduction in the total number of seizures, compared to an average reduction of 18.1% in placebo groups. This represents a 127% higher response rate for patients who received the intervention.

Conclusions: Given these results, it is possible to conclude that the therapeutic response of cannabidiol is worthy of consideration in new protocols and of being added to public healthcare systems for its antiepileptic potential. However, the high efficacy rate observed in the placebo group suggests that other methods of data collection analysis may be employed.”

https://pubmed.ncbi.nlm.nih.gov/40217555/

“Based on the results from the analyzed studies, it can be concluded that the addition of CBD to the treatment regimen for patients with pharmacoresistant epilepsy is beneficial in most cases. The doses of 10 mg/kg/day and 20 mg/kg/day were compared in 5 out of 6 studies, with a higher dose demonstrating superior seizure control. However, the lower dose also showed significant efficacy, making it a viable option for inclusion in treatment and guidelines as well.”

https://aepi.biomedcentral.com/articles/10.1186/s42494-024-00191-2

“Objective: Cannabidiol (CBD) is one of the most prominent non-psychotropic cannabinoids with known therapeutic potentials. Based on its anti-seizure efficacy, the first cannabis derived pharmaceutical grade CBD-based medication was approved in the USA in 2018 for the treatment of seizures in patients 2 years and older. Despite the effectiveness in reducing seizures, there remain several major questions on the optimization of CBD therapy for epilepsy such as the optimal dosage, composition, and route of delivery, which are the main objective of this current study.

Methods: We evaluated the antiseizure effects of CBD through different compositions, routes of delivery, and dosages in a pre-clinical model. We used a kainic acid-induced epilepsy model in C57BL/6 mice, treated them with placebo and/or CBD through inhalation, oral, and injection (intraperitoneal) routes. We used CBD broad spectrum (inhaled and intraperitoneal) vs CBD isolate formulations. We employed the Racine scaling system to evaluate the severity of the seizures, flow cytometry for measuring immune biomarkers and neurotrophic factors, and histologic analysis to examine and compare the groups.

Results: Our findings showed that all forms of CBD reduced seizures severity. Among the combination of CBD tested, CBD broad spectrum via inhalation was the most effective in the treatment of epileptic seizures (p < 0.05) compared to other forms of CBD treatments.

Conclusion: Our data suggest that route and CBD formulations affect its efficacy in the prevention of epileptic seizures. Inhaled broad spectrum CBD showed a potential superior effect compared to other delivery routes and CBD formulations in the prevention of epileptic seizures, which warrants further research.”

https://pubmed.ncbi.nlm.nih.gov/40177581/

https://www.degruyterbrill.com/document/doi/10.1515/tnsci-2022-0362/html

“Pharmaceutical-grade cannabidiol (CBD) is an alternative treatment for patients with drug-resistant epilepsy (DRE). In 2022, the Italian Hospital of Buenos Aires implemented a non-medical change (NMC) of treatment, replacing one commercial pharmaceutical-grade CBD product with another, the latter also being the initial option for new patients.

Our objective was to evaluate the clinical outcomes of the commercial product change in this population.

Methods: Retrospective cohort of DRE patients who either switched from one commercial pharmaceutical-grade CBD product to another or started treatment with the new product. The clinical response was evaluated by changes in seizure frequency, perception of change with the Patient Global Impression of Change (PGIC) scale, and safety considering discontinuation and/or the presence of adverse effects.

Results: Nineteen patients were included, 12 in the change group and 7 in the new start group (7 pediatric and 12 adults). One patient discontinued treatment due to lack of response. Among those who completed follow-up, 8 (44%) reduced seizure frequency, 6 (33%) showed no change, and 4 (22%) increased seizure frequency. According to the PGIC scale, 9 (50%) remained unchanged, 5 (28%) reported barely noticeable changes, and 4 (22%) reported improvement. Adverse events were mild and transient.

Conclusion: The new commercial pharmaceutical-grade CBD product is a safe and valid option both for substitution and initial treatment in patients with DRE. During the treatment period, patients perceived stability or improvement according to the PGIC scale.”

https://pubmed.ncbi.nlm.nih.gov/40163830/