Lithium's well-documented efficacy in preventing suicide over the long term prompts consideration of its potential for more rapid antisuicidal effects. However, evidence supporting such acute efficacy is limited. Weighing against its possible rapid benefits are significant concerns regarding lithium's side-effect profile – particularly toxicity, renal impairment, and weight gain – and the often necessary delay in achieving therapeutic levels. Moreover, the multifaceted nature of suicidality complicates identifying short-term outcomes and disentangling lithium's effects on suicidal thoughts from broader reductions in depressive symptoms. While lithium may remain invaluable for some high-risk patients in emergency settings, its routine use as a rapid-acting agent for acute suicidality is currently not well supported.