This presentation will review the most recent evidence of the role of medications to prevent suicide among patients with mental disorders. We will first conduct a critical review of the role of antidepressants (especially SSRIs), antipsychotics (especially clozapine), opioid receptor agonists (especially buprenorphine), and mood stabilizers (especially lithium). The review will focus on critical aspects of study design and analysis that limit interpretability of current evidence. Then, we will examine a recent randomized trial aimed at estimating the effect of lithium on suicide risk among individuals with mood disorders. This study reported an intent-to-treat 10% increase (with wide confidence intervals) in risk of suicidal behaviors or ideation among people asigned to lithium, compared to placebo in an interim analysis - leading to interruption of the study for futility. However, only 17% of patient adhered to the study protocol. After a state-of-the-art per protocol analysis of the data, where we stopped individuals' follow-up if/when they showed evidence of nonadherence and then conducted an analysis in the restricted sample, adjusting for prognostic factors that predict adherence via inverse probability weighting, we found that lithium effects (compared with placebo) ranging between a 17.5% reduction and a 5.5% increase in the risk of suicidal behaviors were highly compatible with the data. We conclude that a protective effect of lithium on suicidality among patients with bipolar disorder or major depressive disorder cannot be ruled out; and that trialsshould incorporate adequate per-protocol analyses into the decision-making processes for stopping trials for futility.