Abstract Aims To synthesize the available experimental study evidence to estimate the effects of ketamine on suicide ideation (SI) in high-risk individuals. Methods We conducted a systematic review and meta-analysis following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Double-blind randomized controlled trials and open-label studies investigating the safety and effectiveness of ketamine on SI published up to October 2025 were identified. Data were pooled using random-effects meta-analysis. The main outcome was standardized mean difference on SI in high-risk individuals. Secondary outcomes were the percentage of adverse events and the moderator effects. Results We identified 21 studies with a total of 927 participants meeting our inclusion criteria. The pooled effect size for the reduction of SI after ketamine treatment was significant and clinically meaningful (large effect size of −1.40, 95% confidence interval: −2.15 to −0.66, P < 0.001, low–quality evidence). Dissociation (38.8%, P = 0.014), nausea (31.6%, P < 0.001), dizziness (24.7%, P = 0.003), headache (22.0%, P = 0.011) and anxiety (15.8%, P < 0.001) were the frequently reported adverse events. Moderator analyses indicated that the effect was higher in younger individuals and those with severe SI. Conclusions Our findings highlight the effectiveness of ketamine in reducing SI in high-risk individuals, especially younger individuals and those with severe ideation. Nonetheless, additional research is required to better understand optimal dosing regimens and the potential long-term effects of ketamine treatment.
Tang et al. (Thu,) studied this question.