Several studies have shown that antibiotics, analgesic – sedative, and antiseizure medications are among the most commonly used medications in preterm and sick neonates. These infants are at high risk of developing nosocomial infections, central nervous system complications, and are exposed to numerous painful/stressful procedures. These severe, potentially life-threatening complications may have serious short- and long-term consequences and should be prevented and/or promptly treated. Previous studies and reviews have revealed significant variability in medications used in neonatal intensive care units (NICUs) worldwide, especially concerning the indications and dosages of first-line medications. This variability indicates the lack of adequate studies regarding the effectiveness and safety of these medications in neonates, especially the preterm ones. Important obstacles contributing to inadequate studies in preterm infants include difficulties in obtaining parental consent, physicians’ unwillingness to recruit preterm infants, the lack of license for use in neonates, and other scientific and ethical concerns. This review is an update on the use of antimicrobials – antifungals, analgesics – sedatives, and antiseizure medications used in neonates, focusing on existing evidence or knowledge gaps regarding their pharmacokinetics, indications, safety, dosage regimen (dose, dosing interval, route of administration), and evidence-based guidelines for the optimal use in neonates.