French Pharmacovigilance Data Show Most Cannabinoid-Related Seizures Occur in People With Pre-existing Risk Factors | Research

The takeaway

Analysis of 130 seizure reports from French pharmacovigilance databases found 68% of individuals had at least one pre-existing seizure risk factor, with recreational users showing higher risk (79%) than medical users (31%), primarily driven by co-use of epileptogenic medications and other drugs.

Epileptologists, pharmacovigilance specialists, and clinicians prescribing CBD for seizure disorders.

68% had pre-existing seizure risk factors

What the researchers found

130 seizure cases among 4,296 cannabinoid reports (3%). 75.4% were recreational use, 23.3% medical (mostly CBD). 81.1% were serious. 67.7% had pre-existing seizure risk factors (78.6% of recreational vs. 31.0% of medical users). Main recreational risks: epileptogenic medications (39.8%), illicit drugs (33.7%), alcohol (32.7%). Main medical risks: CBD inefficacy (17.2%), fatigue (13.8%), concomitant epileptogenic meds (10.3%).

Why it matters

As CBD gains popularity for epilepsy treatment and recreational cannabis use grows, understanding seizure risks is critical. This study shows most seizures occur in people with pre-existing vulnerability, particularly from drug interactions.

The numbers in context

4,296 cannabinoid reports; 130 (3%) convulsive; 78.7% male; median age 29; 81.1% serious; 38.8% of recreational users had epilepsy history; 68.4% of those were on antiepileptics.

How the study worked

Retrospective analysis of French pharmacovigilance and addictovigilance databases plus Eudravigilance (1985-2023). MedDRA "convulsive" SMQ term with all cannabinoid products. 130 cases analyzed for demographics, circumstances, and risk factors.

What this study cannot tell us

Spontaneous reporting captures only a fraction of events. Cannot establish causation. Recreational use data may include multiple substances confounding attribution. Long study period spans changing cannabis potency and availability.

How to read the evidence

Large pharmacovigilance database spanning decades, but spontaneous reporting and lack of denominator data limit precision.

When this study was published

2025 analysis of 1985-2023 French and European pharmacovigilance data.

The bigger picture

The high prevalence of drug interactions as a risk factor suggests that seizure risk is modifiable. Better screening for concomitant medications and substances could reduce cannabinoid-associated seizure events.

Questions still open

Should CBD prescribing include mandatory drug interaction screening?
Are seizures from recreational cannabis primarily caused by cannabis or co-used substances?

Common questions

Can cannabis cause seizures?

In this analysis, 3% of cannabinoid adverse event reports involved seizures, but 68% of those individuals had pre-existing risk factors including epilepsy history and use of other seizure-triggering substances.

Is CBD safe for people with epilepsy?

Most medical-use seizure cases involved CBD inefficacy or drug interactions rather than CBD directly causing seizures. Interaction screening is important.

Read the original research

Cannabinoids and Adverse Convulsive Effects: A Pharmacovigilance and Addictovigilance Analysis of Cases Reported in France.

Fundamental & clinical pharmacology, 39(4), e70028

View on PubMed ↗Publisher’s paper ↗

Citation

Laroche, Marie-Laure; Labetoulle, Marion; Jouanjus, Emilie; Kröger, Edeltraut; Zongo, Arsène. (2025). Cannabinoids and Adverse Convulsive Effects: A Pharmacovigilance and Addictovigilance Analysis of Cases Reported in France.. Fundamental & clinical pharmacology, 39(4), e70028. https://doi.org/10.1111/fcp.70028