Trazodone is a serotonin antagonist/reuptake inhibitor, approved for treating major depressive disorder (MDD). Oral formulations are widely studied and marketed in several countries worldwide while there is little evidence to support use of parenteral formulation. Our narrative review summarizes pharmacological properties and clinical data concerning use of parenteral trazodone in mood disorders. PubMed and Web of Science were used to identify the most relevant literature. The main evidence concerns four studies evaluating efficacy in major depressive disorder and indicates that trazodone was well tolerated and effective. Off-label use in agitation associated with bipolar disorder is also reported in three studies, although prescription of concomitant treatment, as a confounding factor, may have influenced outcome measures. The limited available evidence supports parenteral trazodone use in major depressive disorder and suggests that trazodone is a suitable option in patients at high risk of treatment-emergent mania (TEM).