BackgroundProblematic substance use is a public health issue that causes significant physical and mental health and societal consequences. Integrated intensive outpatient treatment has shown promise in addressing the multifaceted nature of substance use disorders (SUD). However, the scientific literature on such integrative interventions remains limited.AimThis study aimed to evaluate the outcomes of an integrated, intensive outpatient intervention for clients with SUD in Sweden. Building on previous findings from the same clinic, this study analyzes a new cohort of clients and expands the scope of evaluation to include additional outcome measures, such as craving and affective states, alongside psychological and psychiatric assessments.MethodThis study constitutes a naturalistic service evaluation, not a clinical trial, as it examines the outcomes of a pre-existing, routinely delivered outpatient program within Swedish municipal social services, without randomization, control conditions, or experimental manipulation of treatment. This is a prospective cohort study with a pre–post, within-subject comparison design. Between 2018 and 2023, 127 clients referred by social services, primarily diagnosed with SUD, participated in a four-month cognitive-behavioral therapy-based integrated intervention. 44% (N = 56) of them completed the intervention. Changes in clients’ biological (craving), psychological (hope, hopelessness, self-esteem and affect states) and psychiatric (anxiety and depression) health were assessed using previously validated instruments at intake and at program completion.ResultsStatistically significant, medium-to-large effect size improvements were observed across nearly all outcome domains. Clients who completed the intervention reported increased levels of hope and self-esteem, higher prevalence of positive affect and reduced depression, anxiety, negative affect, and craving (in terms of strength, frequency, and duration). A small, non-significant decrease in hopelessness was also observed, which is discussed in relation to the Bonferroni correction applied and the nature of hopelessness as a deeper cognitive-affective construct.ConclusionThis integrated, intensive, outpatient intervention appears to be effective in reducing biological, psychiatric and psychological symptoms while also enhancing protective factors such as hope, self-esteem, and affective resilience in individuals with SUD. These findings highlight the value of holistic, multimodal approaches in community-based addiction treatment.