Background: Prescription errors are common in hospitalized patients and result in significant morbidity, mortality and costs. Electronic prescriptions with computerized physician order entry systems (CPOE) and integrated computerized decision support systems (CDSS providing online alerts) reduce prescription errors by approximately 50%. However, the introduction of CDSS is often met by opposition due to the flood of alerts, and most prescribers eventually ignore even crucial alerts (“alert fatigue”). 

Objectives: To describe the implementation and customization of a commercial CDSS (SafeRx®) for electronic prescribing in Internal Medicine departments at a tertiary care center, with the purpose of improving comprehensibility and substantially reducing the number of alerts to minimize alert fatigue. 

Methods: A multidisciplinary expert committee was authorized by the hospital administration to customize the CDSS according to the needs of six internal medicine departments at Sheba Medical Center. We assessed volume of prescriptions and alert types during the period February–August 2012 using the statistical functions provided by the CDSS. 

Results: A mean of 339 ± 13 patients per month per department received 11.2 ± 0.5 prescriptions per patient, 30.1% of which triggered one or more CDSS alerts, most commonly drug-drug interactions (43.2%) and dosing alerts (38.3%). The review committee silenced or modified 3981 alerts, enhancing comprehensibility, and providing dosing instructions adjusted to the patient’s renal function and recommendations for follow-up. 

Conclusions: The large volume of drug prescriptions in internal medicine departments is associated with a significant rate of potential prescription errors. To ensure its effectiveness and minimize alert fatigue, continuous customization of the CDSS to the specific needs of particular departments is required.