Unmasking counterfeit semaglutide: analysis of real-world safety data from EudraVigilance.

This pharmacovigilance study examined safety signals associated with potentially counterfeit semaglutide products by conducting a descriptive and disproportionality analysis of Individual Case Safety Reports (ICSRs) submitted to the European pharmacovigilance database EudraVigilance between January 2018 and December 2025. Researchers identified 234 ICSRs linked to suspected counterfeit semaglutide, of which 73.5% involved female patients and 35.5% involved adults. Notably, 89.3% of reported suspected adverse drug reactions (ADRs) were classified as serious. The most commonly reported suspected ADRs were vomiting, nausea, and hypoglycemia. Disproportionality analysis revealed a statistically higher reporting frequency for hypoglycemia, product use in an unapproved indication, malaise, and drug ineffectiveness compared with reports involving non-counterfeit semaglutide. The authors suggest these signals may reflect contamination, incorrect active ingredients, or subtherapeutic dosing in counterfeit products. Limitations include the inherent biases of spontaneous pharmacovigilance reporting (underreporting, lack of denominator data, and inability to confirm causality), reliance on database classifications of "counterfeit," and the descriptive nature of the analysis. The study concludes that pharmacovigilance databases can play a useful role in detecting safety concerns related to counterfeit medicines, and calls for further research.

Why this grade: This is a descriptive, hypothesis-generating pharmacovigilance analysis based on spontaneous adverse event reports, which are subject to significant biases (underreporting, confounding, unverified causality) and cannot establish causal relationships or confirm true incidence rates.