Objective : To describe comorbidities and concomitant medications in patients initiating treatment for hepatitis C virus (HCV) infection with direct-acting antiviral (DAA) regimens in Belgium. Methods : This was a noninterventional, observational, multi-center study of data from patient charts. Adult patients with HCV infection receiving second-generation DAA therapy were included. Comorbidities were assessed at the time of HCV treatment initiation. Concomitant medications were recorded at the time of diagnosis and at treatment initiation. Potential clinically relevant drug-drug interactions (DDIs) were assessed based on information available at www.hep-druginteractions.org. The primary objective was to describe concomitant medication use; secondary objectives were to describe modifications in concomitant therapies and comorbidities. Results : 405 patients were included. A total of 956 comorbidities were reported by 362 patients (median, 2; range, 0-15). The most common comorbidities were hypertension (27.2%); HIV coinfection (22.5%), and type 2 diabetes mellitus (14.3%). Overall, 1455 concomitant medications were being taken by 365 patients (90.1%; median, 3; range 0-16). The most common concomitant medications were psycholeptics (28.6%), antiviral agents (24.2%), and medications for acid-related disorders (21.0%) Overall, 74/365 (20.3%) patients receiving a concomitant medication required an adaptation to their concomitant medication. The medications that most frequently required change were drugs for acid-related disorders (n = 14) and antiviral drugs (n = 5); those that were most frequently stopped were lipid-modifying drugs (n = 25) and drugs for acid-related disorders (n = 13). Conclusion : Physicians are aware of the potential for DDIs with DAAs, but improved alignment between clinical practice and theoretical recommendations is required. ; The authors extend their gratitude to the participants, their families, investigators, and site personnel who participated in this study. Medical writing and editorial ...