It is possible for an untreated infection to cause urethral damage in men, though this seems to be true only in an infection by specific organisms. An untreated or recurrent infection by these organisms may injure the wall of the urethra and cause the passageway to become narrower, making urination difficult. The complete prevention of urination is a very serious condition.
Other potentially serious effects may result from an untreated urinary tract infection. The organisms that caused the UTI may spread to the kidneys and the bloodstream. The kidneys may be permanently damaged. The bloodstream will transport the microbes to other parts of the body. A very serious and life-threatening condition known as Sepsis may appear in this situation.
In Sepsis, the body secretes chemicals into the blood in an attempt to fight the infection. The chemicals cause inflammation, which can often be a helpful process. In Sepsis, however, the inflammation is severe, widespread, and dangerous. Sepsis may be accompanied by a very dangerous condition known as Septic shock. In this disorder, blood pressure falls dramatically.