The adverse effects of cannabis and cannabinoids reveal major psychiatric and neurological risks

A global analysis of adverse effect reports related to cannabis and its derivatives sheds light on often overlooked health risks. Between 2020 and 2024, nearly 10,000 cases were recorded across 44 countries, involving more than 27,000 suspected reactions. This data comes from an international pharmacovigilance database, which collects spontaneous reports of adverse drug effects.

The individuals affected had an average age of 29, with a majority being men. Nearly 70% of the cases were serious, including hospitalizations in 46% of situations and deaths in 29% of cases. France, Greece, and the United States stand out due to a high number of reports relative to their populations. Natural cannabis, Cannabis sativa, is the most frequently reported substance, followed by cannabidiol, a molecule extracted from cannabis often used for its therapeutic properties.

Psychiatric disorders account for nearly 30% of the reported adverse effects. Among these, substance-related disorders, such as dependence or abuse, are the most common. Nervous system disorders, such as seizures, dizziness, or altered consciousness, rank second with 17% of cases. These reactions are particularly associated with Cannabis sativa and cannabidiol. The latter, although often perceived as safe, has been linked to epilepsy seizures in some cases, especially at high doses. Digestive disorders, such as nausea or vomiting, as well as cardiac problems, although less frequent, complete this picture.

Differences between countries can be explained by varying regulatory contexts. In France, where cannabis remains strictly regulated, reports are numerous due to an enhanced surveillance system for substances with addictive potential. In the United States, the progressive legalization of cannabis, whether for medical or recreational use, has led to an increase in reports, particularly for cannabidiol, whose market has exploded in recent years. In Greece, where medical cannabis has been authorized since 2018, reports mainly concern mixtures of THC and CBD, two active molecules in cannabis.

Cannabis sativa primarily acts through THC, a psychoactive molecule that influences brain areas related to cognition, emotions, and reward. This partly explains the observed psychiatric effects, such as suicidal thoughts or mood disorders. Cannabidiol, on the other hand, acts indirectly on the endocannabinoid system, a complex network that regulates various physiological processes, including neuronal excitability. Its use, often for therapeutic reasons, is not without risks, as shown by reports of seizures or treatment inefficacy.

Serious cases, including deaths, highlight the need for increased vigilance from healthcare professionals. The effects vary depending on the products, doses, and modes of consumption, whether medical or recreational. The data also reveal temporal variations, with an increase in reports between 2020 and 2022, possibly reflecting changes in consumption habits and legal frameworks.

This analysis provides a global overview of the risks associated with cannabis and its derivatives, while noting that spontaneous reports do not establish a formal causal link. Reporting biases, differences in pharmacovigilance practices, and the lack of detailed patient information limit the scope of these findings. Nevertheless, this data remains valuable for assessing risks and guiding clinical practices.

Information and Sources

Scientific Reference

DOI: https://doi.org/10.1007/s40263-026-01303-x

Title: Cannabis and Cannabinoid-Related Suspected Adverse Drug Reactions: Global Patterns and Cross-National Analysis Based on VigiBase® Data

Journal: CNS Drugs

Publisher: Springer Science and Business Media LLC

Authors: Pauline Schiro; Mónica Gálvez Pacoricona; Adèle Le Guilloux; Amélia Déguilhem; Sonia Merad; Emilie Bouquet; Marine Auffret; Joëlle Micallef; Maryse Lapeyre-Mestre; Emilie Jouanjus