Social work and substance use research often neglect to make epistemological perspectives explicit in their studies, inadvertently embedding numerous assumptions that remain invisible and uncontested. Consequently, the unchallenged dominance of post-positivist epistemologies in Western European countries becomes (re)produced in social work and substance use education, policies and practices, limiting space for alternative viewpoints. This narrative review examines some of the social work and substance use literature, highlighting the value of making epistemology more explicit and the importance of applying critical epistemologies to counter dominant paradigms. This article makes a unique contribution to substance use literature by examining substance use from post-positivist, social constructivist and critical paradigms and by promoting a critical social work lens. A critical paradigm is particularly useful for questioning prevailing assumptions of substance use as a medical problem requiring professional treatment and for generating greater attention to structural policies that promote a more equitable society. Social work’s commitment to human rights and social justice effectively positions the discipline to apply a critical paradigm to the field of substance use studies.