The use of antidepressant medication in people with bipolar disorder has been a source of controversy.4 Although widely used, there is poor evidence in favour of antidepressant therapy in bipolar disorder, with few well-designed good-quality studies forming an evidence base.4 This was acknowledged by a task force of the International Society for Bipolar Disorders, which failed to make broad recommendations because of the lack of good evidence, although conceded that individual patients may benefit from the use of antidepressant therapy.4

References:
1. McGirr A, Vöhringer PA, Ghaemi SN, et al. Safety and efficacy of adjunctive second-generation antidepressant therapy with a mood stabiliser or an atypical antipsychotic in acute bipolar depression: a systematic review and meta-analysis of randomised placebo-controlled trials. Lancet Psychiatry 2016; 3 (12): 1138–1146.
2. Hu Y, Zhang H, Wang H, et al. Adjunctive antidepressants for the acute treatment of bipolar depression: a systematic review and meta-analysis. Psychiatry Res 2022; 311: 114468.
3. Nierenberg AA, Agustini B, Köhler-Forsberg O, et al. Diagnosis and treatment of bipolar disorder: a review. JAMA 2023; 330 (14): 1370–1380.
4. Pacchiarotti I, Bond DJ, Baldessarini RJ, et al. The International Society for Bipolar Disorders (ISBD) task force report on antidepressant use in bipolar disorders. Am J Psychiatry 2013; 170 (11): 1249–1262.