Explaining the causes and motivations for multiple substance use from the perspectives of users and therapists: A qualitative study.

Background: The high prevalence of multiple substance use (MSU) is concerning, given the weak awareness about this issue and the potential impact this unawareness has on the severity of substance use disorder (SUD) and treatment outcomes. The aim of this study is to identify and elucidate the causes and motivations for MSU from the viewpoints of users and therapists in this field.

Methods: In this qualitative study, the conventional content analysis approach and purposive sampling were utilized.