Complications

When treated promptly and properly, bladder infections rarely lead to complications. But left untreated, they can become something more serious. Complications may include:

• Kidney infection. An untreated bladder infection can lead to kidney infection, also called pyelonephritis (pie-uh-low-nuh-FRY-tis). Kidney infections may permanently damage your kidneys.

  Young children and older adults are at the greatest risk of kidney damage from bladder infections because their symptoms are often overlooked or mistaken for other conditions.

• Blood in the urine. With cystitis, you may have blood cells in your urine that can be seen only with a microscope (microscopic hematuria) and that usually resolves with treatment. If blood cells remain after treatment, your doctor may recommend a specialist to determine the cause.

  Blood in the urine that you can see (gross hematuria) is rare with typical, bacterial cystitis, but this sign is more common with chemotherapy- or radiation-induced cystitis.