Abstract
Tamoxifen, a selective estrogen receptor modulator (SERM), has long been a cornerstone in the treatment of hormone receptor-positive breast cancer. While its benefits in reducing the risk of recurrence and mortality in this patient population are well-established, emerging evidence suggests a potential association between tamoxifen use and adverse psychiatric effects, including suicidality. Despite extensive research on the clinical efficacy of tamoxifen, the exploration of its psychiatric side effects, including suicidality, remains relatively understudied. We present a case of a woman with a medical history of depression and invasive lobular carcinoma of the left breast who developed a severe episode of recurrent major depressive disorder (MDD) and attempted suicide with a benzodiazepine overdose upon initiating tamoxifen for her breast cancer. This case report aims to contribute to the growing body of literature on the relationship between tamoxifen and suicidality by presenting a detailed analysis of a patient who experienced suicidality while undergoing tamoxifen therapy.