Urinary tract infections (UTIs) are among the most common bacterial infections, both in out- and inpatient settings. The clinical spectrum is heterogeneous and ranges from benign, often self-limiting, uncomplicated infections to complicated urinary tract infections (cUTIs) with life-threatening courses. Uncomplicated UTIs include acute, sporadic, or recurrent lower (uncomplicated cystitis) and/or upper (uncomplicated pyelonephritis) urinary tract infections, limited to non-pregnant women with no known relevant anatomical and functional abnormalities within the urinary tract or comorbidities. Pyelonephritis is characterized by an additional occurrence of fever, chills, flank pain, nausea, vomiting, or costovertebral angle tenderness, with or without the typical symptoms of cystitis. A subdivision into mild to moderate forms of the disease, as well as severe infections, is useful for stratifying whether outpatient therapy with oral antibiotics or inpatient therapy with intravenous antibiotics should be performed. Fluoroquinolones and cephalosporins are available for both oral and intravenous therapy. A therapy period of 7–14 days is sufficient. Complicating factors must be excluded in any case, as these infections have a higher risk of chronicity, recurrence, and/or progression and may be associated with severe disease progression.