Due to COVID-19 global pandemic, treatment with HCQ, although controversial, has been widely prescribed. The aim of our study was to identify drug-drug interactions (DDI) between HCQ and long-term treatments of COVID-19 patients, focusing on drugs which can cause or promote QT prolongation. From March 13 to April 14 2020, 61 patients were treated with HCQ in our hospital. More than a half of patients (62%) had at least one DDI between HCQ and their long-term treatments. A large number of drug classes were involved, included contraindicated drugs The mean of co-medication contraindicated or not recommended with HCQ per patient was 1.9 CI95% [1.48 to 2.27]. All contraindicated drugs were discontinued at the beginning of HCQ treatment due to multidisciplinary meetings involving physicians and clinical pharmacists. To our knowledge this is the first study about DDI between HCQ and long-term treatments of COVID-19 patients.