Previous studies on the prevalence of drug-drug interactions (DDIs) have largely been restricted to specific hospital departments. We identified common drug combinations and potential drug-drug interactions (pDDIs) in an entire hospital population throughout 1 year. Frequently administered drug combinations involved analgesics, cardiovascular medicines and gastrointestinal medicines. The prevalence of pDDIs among newly hospitalised patients was 2.6%. The most common pDDIs were ibuprofen – paracetamol, pantoprazole – paracetamol and morphine – paracetamol. Critical pDDIs were rare and only accounted for 0.4% of pDDIs.