UTIs are common infections, usually caused by bacteria, in the bladder or urethra.
There are several kinds of UTI. The type of a UTI depends on where the infection occurs. For example:
- Urethritis is an infection in the urethra.
- A bladder infection is called cystitis.
If left untreated, a UTI could travel up one or both ureters to the kidney(s), causing pyelonephritis or a kidney infection. Kidney infections can become serious and may require hospitalization as part of treatment. UTIs are not the only cause of kidney infections.
UTIs are more common among women than among men. They also can affect children. For information about UTIs in children, https://www.niddk.nih.gov/health-information/urologic-diseases/urinary-tract-infections-in-children.