Abstract The use of medicinal cannabis to improve mental health is increasing globally, both in clinical settings and through self-medication. This involves a variety of products containing ∆9-tetrahydrocannabinol (THC), cannabidiol (CBD), THC + CBD combinations, or derivatives. This review provides an up-to-date overview of the positive and negative effects of medicinal cannabis on mental health diagnoses and related symptoms of the Diagnostic and Statistical Manual of Mental Disorders 5th Edition. Searches in PubMed, PsycInfo, Embase, and the Cochrane Library (October 2023 and July 2024) identified 18,341 studies, of which 49 controlled studies from 15 different countries were included. All studies focused on treatment-seeking participants using medicinal cannabis for (symptoms of) their mental health diagnosis....