OBJECTIVES We aimed to evaluate and quantify incompatible coadministrations of continuous intravenous medication in the daily clinical practice of a PICU/NICU. METHODS We conducted a retrospective, observational study in the setting of an 18-bed PICU/NICU. All concurrently administered continuous infusions, including blood products and parenteral nutrition, were analyzed for 2 months. Raw electronic data were retrieved and subjected to quality controls. Infusion combinations were classified as compatible, incompatible, no data, or variable according to the internal hospital charts, Trissel's database, and the Swiss summary of product characteristics. For situations with incompatible coadministrations, we assessed alternative distributions of infusions among the currently available lumen. RESULTS Data for 100 patients were analyzed. Patients were exposed to a mean of 6.9 ± 3.6 individual continuous infusions administered through 3.8 ± 1.8 lumina. Among the 1447 coadministered continuous infusions, we detected 146 incompatible combinations (10%), resulting in 105 individually relevant incompatible situations. Furthermore, 185 combinations (13%) were not covered by internal compatibility charts, and for 207 combinations (15%) no data on compatibility were available. We found that 58% of the incompatible situations could have been avoided by a redistribution of the infusions among the available lumina. CONCLUSIONS Most infusion combinations in the studied PICU/NICU were compatible and covered by the internal compatibility charts. However, we also identified concurrent administrations of incompatible infusions or for which compatibility data are not available. A significant reduction of coadministrations of incompatible infusions could be achieved through optimal use of available lumina.