Following informed consent, patients will be randomized to receive 10 days of cephalexin or PDAD (minimum of 3 days of cephalexin followed by placebo once patient reports 24 hours of symptom resolution). Patients will be evaluated at day 1 in-person, then daily using a mobile cellphone application to assess acute uncomplicated pyelonephritis (AUP) symptoms and quality of life (QOL). Urine samples will be collected at in-person visits at day 1, 3 weeks, and 4 weeks. Study feasibility will be assessed through day 90.