Background: Given the paucity of data concerning the care of adolescents attending an emergency department (ED) for mental disorders, we performed an observational study with the aim to describe psychotropic drug use in an Italian ED. Methods: A retrospective chart review of adolescents (13–17 years) visited in the ED of the San Paolo University Hospital in Milan for mental disorders between January and June 2018 was conducted. Information concerning age, gender, type of disorder, psychotropic drug use in the ED and outcome of the visit were analyzed, using an anonymous patient code. Results: A total of 1298 adolescents, 13–17 years old, were visited in the ED, 56 (4%) of whom had a diagnosis of mental disorder (34 females and 22 males). The most common disorder was anxiety (21 patients), followed by predominant psychomotor disorder (13 patients). In all, 30 adolescents received a psychotropic drug. Benzodiazepines were the most commonly used drugs (73% of the subjects), and delorazepam was administered/prescribed to 17 adolescents, despite the fact that evidence on its safety, efficacy, and its off-label use in the pediatric population is lacking. Conclusions: One out of two adolescents attending the ED for an acute episode of mental disorder received a psychotropic drug prescription, mainly in an off-label manner. More evidence is needed to guide the pharmacological management of acute episodes of mental disorders.