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

BACKGROUND: Seizures after the use of cannabinoids are reported, but no precise descriptions of the characteristics of subjects and factors that may trigger seizures are available. OBJECTIVES: To study the characteristics and circumstances associated with the occurrence of seizures in individuals using cannabinoids for medical or recreational purposes. METHODS: A retrospective analysis of spontaneous reports of adverse drug effects issued by the French pharmacovigilance and addictovigilance systems, and by manufacturers, extracted data from the Eudravigilance database (01/01/1985-21/07/2023). The request used the broad MedDRA SMQ term 'convulsive', with all products containing cannabinoids (THC, CBD, cannabis or natural cannabinoids). RESULTS: Among 4296 notifications with cannabinoids, 130 (3%) reports of convulsive effects were analysed: 29 cases (23.3%) related to medical use (27 CBD, 1 THC and 2 combined THC/CBD preparations) and 98 (75.4%) related to recreational use. The median age was 29.0 years (min-max: 3-75), 78.7% were men and 81.1% were serious cases. Among the recreational users, 38.8% used Cannabis sativa with a history of epilepsy, and 68.4% of them were taking antiepileptics. In total, 67.7% of individuals had at least one risk factor for seizures, i.e., 31.0% among medical users and 78.6% among recreational users. The main risk factors with medical use were inefficacy of CBD (17.2%), fatigue (13.8%) and concomitant epileptogenic medications (10.3%). The main risk with recreational use was concomitant epileptogenic medications (39.8%), consumption of illicit drugs (33.7%) and alcohol (32.7%). CONCLUSION: This analysis demonstrates the importance of alerting cannabinoid users, particularly recreational cannabis users and those with a history of epilepsy, about seizure-associated risks. Moreover, educational information should be provided together with the prescription of licensed cannabinoids and medical cannabis.