An illness in any part of the urinary tract, the system of organs that makes urine.

Urinary tract infections (UTIs) often start when bacteria get into the tube through which urine leaves the body, the urethra. Most UTIs involve the lower urinary tract, which includes the bladder and the urethra. Risk factors include being born female, using diaphragms or spermicide for birth control and having blockages in the urinary tract.

UTI symptoms can include a strong urge to urinate that doesn't go away or a burning feeling while urinating. The urine may look cloudy, red, bright pink or cola-colored. It may have a strong odor. Pain in the pelvis also can be a symptom. Sometimes, UTIs cause no symptoms.

Medicines that fight bacteria, called antibiotics, are often the first treatment for UTIs. Serious UTIs may need treatment with antibiotics that are given through a vein, which happens at a hospital. Pain medicine can ease burning while urinating.