The study will be a prospective randomized double-blind placebo-controlled trial of mirabegron for medical expulsive therapy (MET) in patients with a CT scan-proven ureteral stone between 4 to 10 mm undergoing expectant management. Subjects will be distributed at a 1:1 ratio between the control and treatment groups. The treatment group will receive mirabegron and the control groups will receive a placebo. Both groups will receive analgesics and hydration will be recommended. All subjects will then be followed for 30 days to determine the proportion of subjects with spontaneous passage. Patients will record narcotic usage and pain scores during this time. If there is stone persistence in the ureter based on imaging (CT scan of the abdomen and pelvis versus renal ultrasound plus KUB), then the patient will undergo ureteroscopy with stent placement. In these patients, treatment will continue while the stent is in place and patients will fill out a validated questionnaire regarding stent pain.