What happens if you don't treat a urinary tract infection?

Resolves slpwly: An untreated urinary tract infection will usually eventually clear up on it's own. However, sometimes the infection will ascend to the kidneys (called pyelonephritis) which can damage the kidneys - and on rare occasion the infection can lead to sepsis and death if untreated. The benefit of treatment is a speedier resolution, with much less risk of complications.