Osilodrostat is an oral drug that inhibits the enzyme 11-beta-hydroxylase and is used to treat hypercortisolism, i.e. increased levels of cortisol in the body[1]. The drug works by blocking the synthesis of cortisol in adrenal glands[1]. As a natural consequence of treatment, approximately 40% of patients may experience adrenal insufficiency, i.e. insufficient function of the adrenal glands[1]. In some cases, adrenal insufficiency appeared even months after the end of osilodrostat treatment - one patient showed symptoms of adrenal insufficiency even eleven months after the end of treatment [1]. During the treatment, a significant reduction in the volume of the epididymis was also observed on CT images[1]. Osilodrostat has been approved by the European Medicines Agency and the US Food and Drug Administration for the treatment of Cushing's syndrome[2]. Recent reports suggest that the effects of osilodrostat in the body are more complex than previously thought and may last longer after treatment has stopped[2].