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The urgent need for appropriate treatment for suicide, the tenth leading cause of death, has led to numerous studies. This study aims to systematically identify and appraise systematic reviews with or without meta‐analyses investigating ketamine in suicidal ideation and behaviours. Scopus, ISI, Embase, PubMed, CINAHL, PsycINFO, Cochrane Library, Google Scholar and two registries were searched without any restrictions for systematic reviews investigating the efficacy of ketamine on suicidal ideation and behaviours. The primary outcome was the final inference of ketamine effectiveness. A formal narrative synthesis was conducted, and the AMSTAR‐2 tool was used to evaluate the quality of the studies. Of 27 studies that addressed ketamine for suicidal ideation, only four reported mixed or negative results, and out of nine reviews, esketamine was significantly beneficial only in five. A transient rise in pulse rate and blood pressure, dissociation, confusion, blurred vision, nausea and vertigo were the most common adverse effects; however, most were mild. More than two‐thirds of the included studies qualified as of low or critically low quality. Preliminary evidence for the short‐term efficacy of ketamine in suicidality was noted by the majority of reviews; however, long‐term effects remained unknown. Due to the low quality of many studies and the limitations of core studies, further research is required.

The increasing prevalence and burden of suicide have led to numerous studies to identify its risk factors. Cannabis is the most common illicit substance detected in suicide victims’ toxicology tests. This study aims to identify and appraise systematic reviews investigating suicidality after using cannabis and cannabinoids. Seven databases and two registries were searched without restrictions for systematic reviews investigating cannabis effects on suicidality. AMSTAR-2 was used for quality assessment and corrected covered area and citation matrix were used to determine overlap. Twenty-five studies were included, of which 24 were on recreational use and one was on therapeutic use. Only three of the studies on recreational use reported no effect or inconsistent results. Evidence generally showed a positive association between cannabis use and suicidal ideation and attempt among the general population, military veterans, and bipolar or major depression patients. A bidirectional causal association between cannabis and suicidal ideation was also mentioned. Moreover, a younger age of initiation, long-term use, and heavy consumption were reported to be associated with even worse suicidal outcomes. On the contrary, current evidence indicates that the therapeutic cannabis is safe. In conclusion, the literature supports the cannabis-suicidality association in recreational use but considers cannabidiol safe for treatment. Further studies with quantitative and interventional approaches are recommended.

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