Hospital pharmacy compoundings are crucial for maintaining patient care. They are time- and cost-effective in hospital pharmacy settings because they prevent waste, preparation errors, dosage errors, microbial contamination and breakage due to handling. Unfortunately, the drawbacks of hospital pharmacy compounding include the selection of inappropriate medical devices (MDs) for long-term storage, which could directly impact patients. In this study, three important hospital pharmaceutical compoundings, vancomycin in prefilled syringes (PFSs) made of polypropylene (PP) material, paediatric parenteral nutrition (PN) in ethylene vinyl acetate (EVA) bags and diluted insulin in cyclic olefin copolymer (COC) vials, were selected for leachate study and risk assessment. These compounds were studied via a semiquantitative screening approach by means of an ultrahigh-performance liquid chromatography coupled to high-resolution mass spectrometry (UHPLC-HRMS) with postcolumn infusion and an in-house built database. 17 leachable compounds for the PFS, 25 for the PN, and 10 for the vial were identified, and their concentrations were estimated for toxicological assessments. In conclusion, all MDs used in hospital pharmacy compoundings were observed suitable thanks to risk assessments. However, suitable MDs recommended for long-term storage would remain with polymers like COC, for higher safety when exposed to frail and vulnerable patients like neonates and infants.