Fondaparinux sodium is a synthetic agent that inhibits factor Xa and is used to prevent blood clots after orthopedic surgery and to treat unstable angina pectoris and myocardial infarction[1][2]. The study analyzed the safety profile of fondaparinux using data from the FDA (FAERS), VigiAccess and the Japanese JADER database from 2003 to 2025[1]. Researchers identified 5,700 adverse event reports, with 81.98% occurring within 30 days of drug administration, with a peak at an average of 7 days[1]. The analysis confirmed positive signals for hemorrhagic complications in all patient groups, with women showing a higher risk of bleeding and elderly patients (≥ 65 years) having an increased risk of anemia and skin necrosis[1]. Pediatric patients had a rare but significantly increased hepatotoxicity[1]. The study identified unbalanced signals including hematemesis (ROR = 14.52) and skin necrosis (ROR = 27.29) that require further clinical monitoring[1]. The authors emphasize that these findings are a hypothesis for further investigation and not confirmation of definitive causality[1].