How serious is a urinary tract infection?

Serious if untreated: Urinary tract infections can cause pain, urgency and frequency of urination. If untreated the kidneys could be affected.

It depends: Most infections are simple bladder infections, although sexually transmitted diseases (which can sometimes cause sterility or serious or overwhelming infection) can have similar symptoms. It is important to make sure that a urinary tract infection is not involving the kidneys, or leading to infection in the blood.

Mostly not serious: Not serious if UTI is confined to bladder & treated promptly. Utis reaching the kidney, by bladder reflux or aggressive bacteria can result in a kidney infection/pyelonephritis. This is potentially serious because infection can kidney damage & scarring. Serious kidney infections affecting both kidneys, or a solitary kidney can lead to kidney failure & death if not treated. Thus treat all utis.