Lithium lowers the risk of suicide in both bipolar disorder and unipolar depression, a systematic review and meta-analysis has found. Overall, 48 randomised controlled trials, involving 6,674 participants, were included. Patients had a diagnosis of bipolar disorder (19 trials), unipolar depression (12 trials) or a mix of bipolar, unipolar or schizoaffective disorder (17 trials). They were randomised to receive either lithium, an active comparator or placebo over a period of at least three months.