Objectives To analyse the impact of the computerised prescription order entry (CPOE) alerts on the reduction of errors due to medication interactions in the prescribing process of vitamin K antagonists.

Methods Prospective study over 3 months in a 1400-bed university tertiary care centre gifted with CPOE software, which includes medication interaction alerts. Adult patients receiving oral anticoagulant treatment with vitamin K antagonists with international normalised ratio ≥4 were included. The reason for their hyperanticoagulation was evaluated. We analysed the impact of incorporating interactive alerts in the prescription of vitamin K antagonists in terms of reduction of medication errors by comparing results with a previous period with no interaction alerts incorporated in the software. The main outcome measure was medication errors.

Results Implementation of alerts reduced the number of medication errors caused by drug interactions by 71.4% (p=0.02). The number of errors diminished from 10.5 per month to 3 when interaction alerts were introduced.

Conclusions Implementation of a CPOE interaction alert programme reduces interaction errors. Additionally, the use of this new technology allowed us to perform a thorough analysis of data and to identify and implement actions aimed at improving patient safety.