Background. This study aimed to investigate the prevalence of smoking, alcohol, and substance abuse disorders among adolescents hospitalized in a university hospital child and adolescent psychiatry inpatient unit with different diagnoses, and to determine the rates of these disorders according to the mental illness diagnosis groups.

Methods. The study was conducted with 346 adolescents aged 12-18 who had been hospitalized with any psychiatric diagnosis between September 2016 and January 2020 in the child and adolescent psychiatry inpatient unit. The study considered the psychiatric diagnoses, based on the results of the DSM-5-based psychiatric interview; sociodemographic and clinical characteristics; the psychopathology history of first-degree relatives; comorbidities; length of hospital stay; income levels, and smoking, alcohol, and substance abuse.

Results. Twenty-four percent (n=83) of the participants had been smoking for 18 months or longer, 6.9% (n=24) were using alcohol, and 1% (n=28) were substance abusers. When the diagnosis distributions were examined, smoking was found to be higher in those with depressive disorders and trauma and related disorders, while smoking, alcohol, and substance use were found to be higher in the disruptive behavior disorder group. Smoking was found to be significantly lower in the obsessive-compulsive disorder group.

Conclusions. Smoking, alcohol, and substance use among inpatient children and adolescents may worsen their existing psychopathology, so health professionals working in this field should consider this situation.

Keywords: adolescent, alcohol, psychiatry clinic, smoking, substance