Polytherapy in neonatal and pediatric patients requiring parenteral nutrition (PN) administration is a challenging task. Due to limited intravenous access, the Y-site administration of medication with PN admixtures is sometimes inevitable. This review aims to summarize the evidence on the compatibility of the Y-site of intravenous medications and PN admixtures in neonatal and pediatric settings. A literature review of the PubMed database was conducted. Articles published between January 1995 and November 2023 concerning the compatibility of intravenous medications in pediatric-dose PN admixtures or with intravenous lipid emulsions only were included. Studies concerning the compatibility/stability of the ingredients of PN admixtures and those concerning unapproved medications were excluded. Based on the methodology used, the quality of the research was assessed. A total of fifteen studies were explored. Among fifty-five different drug substances assessed in the research reviewed, 56% (31/55) were found to be compatible, 13% (7/55) were assigned as incompatible, and for 31% (17/55), the data were ambiguous. None of the studies demonstrated an "A" grade (very high quality), and the grades "B", "C", and "D" were assigned to four, six, and five studies, respectively. The compatibility data are presented in two tables, the first concerning the simultaneous administration of medications with 2-in-1 PN formulations (without lipids) and the second, with 3-in-1 formulations (with lipids) and lipid emulsions. This review presents data on compatibilities between intravenously administered medications and PN mixtures intended for neonates and pediatric patients found in the PubMed database. It should be highlighted, however, that this work has some limitations. The clinical decisions on the simultaneous administration of intravenous medication with PN admixtures should be based not only on this review (including assessment of the quality of evidence) but also on manufacturer data, available electronic databases, and incompatibility data for PN admixtures dedicated to adult patients.