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. Deep semi-structured exploratory interviews were conducted with 17 substance users and 8 addiction therapists (including 4 psychiatrists, 3 general practitioners, and 1 psychologist). Field notes were also taken to identify and explain the motivations and reasons for MSU from the perspectives of users and therapists. The data were analyzed comparatively and simultaneously using the method suggested by Graneheim and Lundman (2004). Results: Based on the findings of this study, the motivations for MSU are reflected in four main categories: 'Pharmacological factors' with subcategories such as achieving desired states and mitigating the undesirable effects of substances through leveraging the balancing, synergistic, and antagonistic effects of substances, substituting the effects of other substances, self-medication of the undesirable effects of other substances, enhancing the overall consumption experience such as heightened peak experience and enhanced pleasure, moderating the come-down, and seeking euphoria experiences in different substances; 'Biological factors' with subcategories including different neurobehavioral systems, individual differences determining substance dependence and the somatic-neural vulnerability of consumers; 'Psychosocial factors' with the subcategories of undesirable norms like the need for acceptance and social interactions, the context of substance use, consumers' experiences and expectations of substance use, and the maladaptive personality traits of consumers; and 'Addiction's inevitability' with the subcategories of coercion and the need to maintain equilibrium, and the difficulties of substance detoxification. Conclusion: The motivations behind Multiple Substance Use (MSU) behaviors are multifaceted, including pharmacological, biological, psychosocial, and addiction-related factors. Recognizing and comprehending the interplay between these factors and motivations can inform better prevention strategies, assessment of treatment needs, and enhancement of treatment outcomes for individuals dealing with MSU.