IntroductionTreatment of mood and cognitive symptoms of patients with bipolar disorder is associated with many complications and is generally not associated with therapeutic satisfaction. In this clinical trial, we evaluated the effectiveness of spironolactone in controlling mood and cognitive symptoms, sleep quality, appetite, and body mass index in patients with bipolar disorder in manic episodes.MethodsSixty inpatients with bipolar disorder in manic episodes were treated with spironolactone/placebo in an 8‐week randomized, double‐blind, placebo‐controlled clinical trial. They were evaluated using the Young Mania Rating Scale (YMRS), mini‐mental state examination (MMSE), Pittsburgh sleep quality index, Simplified Nutritional Appetite Questionnaire, and body mass index in weeks 1, 4, and 8.ResultsFor cognitive impairment (MMSE), there were significant interaction effects of group and time at week 8 (B = −1.60, SE = 0.69, t = −2.33, p = .021) such that individuals in the spironolactone group experienced more improvement in their cognitive performance. For manic symptoms (YMRS), there were no significant interaction effects of group and time at week 8 (B = −2.53, SE = 1.46, t = −1.73, p = .085).ConclusionsConsidering the promising findings in this clinical trial, further study of spironolactone as adjunctive therapy in bipolar disorder in manic episodes with larger sample sizes, multicenter settings, and longer follow‐ups are recommended.