Safety Profile of Vitamin D in Italy: An Analysis of Spontaneous Reports of Adverse Reactions Related to Drugs and Food Supplements

Vitamin D (VitD) is largely used in Italy, often inappropriately; thus, an evaluation of its safety is a crucial issue. This study analyses the adverse reactions (ARs) associated with the use of products containing VitD (VitDps) reported to the Italian National Pharmacovigilance and Phytovigilance networks. From March 2002 to August 2022, a total of 643 and 127 reports concerning 903 and 215 ARs were retrieved from Pharmacovigilance and Phytovigilance networks, respectively. Overall, 332 (29.6%) ARs were classified as serious, and the most described ones were hypercalcaemia, renal failure and tachycardia. Serious AR risk was significantly higher for subjects using more than four concomitant products (OR 2.44 [95% CI 1.30-4.60]) and VitD doses higher than 1000 IU/day (OR 2.70 [95% CI 1.30-5.64]). In Italy, there was a modest decrease in AR reporting, despite the slightly increased use of VitD during the COVID-19 pandemic. To the best of our knowledge, this is the first study describing all VitDps-related ARs observed in the Italian general population. Since underreporting is the main limitation of the safety reporting systems, the necessity to continue ARs monitoring, also using real-world data on VitDps prescription, use and outcome patterns is highlighted.