Unlicensed CBD products in Europe linked to liver problems and seizure worsening

What the researchers found

Serious adverse reactions made up 18.9% of all reported events for unlicensed CBD. They were most common in men (58.8%) and adult age groups, with 38.8% of reports involving epilepsy treatment. The most frequent serious effects were mental disorders, hepatic disorders, and aggravation of pre-existing epilepsy. Clobazam and valproic acid were the most common co-administered drugs.

Why it matters

With unlicensed CBD products widely available across Europe, this safety analysis reveals that serious adverse effects occur, particularly when CBD is used for epilepsy alongside other antiepileptic drugs. This underscores the risk of using unregulated CBD as a substitute for approved formulations.

The numbers in context

18.9% of all CBD adverse events were classified as serious. 58.8% of serious cases were in men. 38.8% used CBD for epilepsy. Most common drug interactions: clobazam, valproic acid, then cannabis.

How the study worked

Analysis of serious suspected adverse reactions to unlicensed CBD products reported in EudraVigilance, the European Medicines Agency adverse event database. Reports were analyzed by age, sex, adverse reaction type, indication, and concomitant drugs.

What this study cannot tell us

Passive pharmacovigilance data has inherent reporting biases and likely underestimates true adverse event rates. Product quality and actual CBD content of unlicensed products are uncertain. Cannot establish causation from adverse event reports alone.

How to read the evidence

European Medicines Agency pharmacovigilance data provides broad surveillance but relies on voluntary reporting and cannot confirm causation. Product quality in unlicensed CBD adds uncertainty.

When this study was published

Published in 2024 in Phytotherapy Research, analyzing EudraVigilance data.

The bigger picture

The global CBD market includes many unregulated products with variable quality and purity. This European pharmacovigilance data shows that even a compound widely perceived as safe can produce serious adverse effects, especially when used alongside prescription medications without medical oversight.

Questions still open

• Are the serious adverse events caused by CBD itself or by contaminants in unlicensed products? Would the same adverse effect profile appear with pharmaceutical-grade CBD? How does the safety profile of unlicensed CBD compare across different European countries with varying regulations?

Common questions

Read the original research

Pharmacovigilance of unlicensed cannabidiol in European countries.

Phytotherapy research : PTR, 38(1), 74-81

Citation

Calapai, Fabrizio; Esposito, Emanuela; Ammendolia, Ilaria; Mannucci, Carmen; Calapai, Gioacchino; Currò, Mariaconcetta; Cardia, Luigi; Chinou, Ioanna. (2024). Pharmacovigilance of unlicensed cannabidiol in European countries.. Phytotherapy research : PTR, 38(1), 74-81. https://doi.org/10.1002/ptr.8028

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