Objective: This assessment discusses the partnership in between cannabis use and psychotic, bipolar, depressive, and anxiousness issues, as properly as suicide. It summarizes epidemiological proof from cross-sectional and lengthy-term potential research and considers doable etiological mechanisms. Strategies: Systematic testimonials and methodologically robust research in the field (from inception to February 2019) had been identified applying a extensive search of Medline, PsychINFO, and Embase and summarized applying a narrative synthesis. Outcomes: Constant proof, each from observational and experimental research, has confirmed the significant function of cannabis use in the initiation and persistence of psychotic issues. The size of the impact is connected to the extent of cannabis use, with higher threat for early cannabis use and use of higher-potency varieties and synthetic cannabinoids. Accumulating proof suggests that frequent cannabis use also increases the threat for mania as properly as for suicide. On the other hand, the impact on depression is much less clear and findings on anxiousness are contradictory with only a couple of methodologically robust research. Moreover, the partnership with frequent mental issues may perhaps involve reverse causality, as depression and anxiousness are reported to lead to higher cannabis consumption in some research. Pathogenetic mechanisms concentrate on the impact of tetrahydrocannabinol (THC, the most important psychoactive ingredient of cannabis) interacting with genetic predisposition and probably other environmental threat elements. Cannabidiol (CBD), the other significant ingredient of standard cannabis, ameliorates the psychotogenic effects of THC but is absent from the higher-potency varieties that are increasingly offered. Conclusions: The proof that heavy use of higher-THC/low-CBD forms of cannabis increases the threat of psychosis is sufficiently sturdy to merit public well being education. Proof of equivalent but smaller sized effects in mania and suicide is increasing, but is not convincing for depression and anxiousness. There is a lot existing interest in the possibility that CBD may perhaps be therapeutically helpful.