Failure mode and effect analysis (FMEA) is widely used to identify latent safety hazards. The authors of this study proposed combining healthcare failure mode and effect analysis (HFMEA) with computer simulation (HFMEA-CS) for prospective risk analysis of complex and potentially harmful processes. Use of HFMEA-CS to analyze medication processes during admission and discharge for patients with a rare adrenal tumor led to a reduction in drug delivery and system errors, as well as increased drug adherence.