Health-care providers use computerized provider order entry as a component of the electronic medical record system in conjunction with clinical decision support. An important aspect of clinical decision support is screening of drug-drug interactions including contraindications in the labeling approved by the Food and Drug Administration. Currently, there are inconsistencies between the knowledge databases and the official package labeling for contraindications on drug-drug interactions. Unnecessary warnings can cause alert fatigue among clinicians and potentially influence adoption of true contraindications for drug prescribing. Each Institution should evaluate the accuracy and completeness of the knowledge databases used for screening of contraindications on drug-drug interactions.