The Roots of Problematic Polydrug Use in Emotional Problems and Suicide Behavior: A Cross-Sectional Study.

: Problematic polydrug use represents a relevant public health concern, with strong relationships with mental health problems and suicide behavior. Existing studies have just focused on problematic use, overlooking the potentially cumulative effect of coexisting substance use and addictive behaviors. This study aims to analyze the association between the polydrug use profile (no problematic use, problematic use of a single drug, and polydrug use) and mental health outcomes, specifically anxiety symptoms, depressive symptoms, and suicide behavior. : A sample of 1307 Spanish young adults (66.2% male; = 21.2 years, = 3.31) were assessed for problematic use of substances and behavioral addictions as well as for the internalizing symptoms and suicide behavior. Participants were categorized into three groups: no problematic drug use ( = 880), problematic single drug use ( = 316), and polydrug use ( = 111). : Results showed an increasing level in depressive symptoms and suicide behavior with polydrug use, with significant differences between groups ( < 0.05). Moreover, both groups of problematic use presented higher levels of anxiety than no-use participants, regardless of the number of use modalities. : These findings suggest that problematic polydrug use is associated with greater clinical severity, particularly in terms of depressive symptoms and suicide behavior, while anxiety remains elevated even when a problematic single drug pattern is observed. This study highlights the importance of considering polydrug use in dual diagnosis and the need for an integrative clinical approach.