Efficacy and safety of long-term antidepressant treatment for bipolar disorders – A meta-analysis of randomized controlled trials

•Long-term antidepressant (AD) use for bipolar disorder (BD) is highly contentious and urgently needs more research evidence.•Long-term AD treatment may reduce risk of depression without increasing risk of mania/hypomania in BD, particularly in BD II.•AD combined with mood stabilizers (MS) may the superior to either AD or MS monotherapy in BD treatment.