May also be called: Cystitis; Pyelonephritis; Bladder Infection; Kidney Infection A urinary tract infection (UTI) is an infection in one or more of the structures of the urinary tract. UTIs are more common in females. More to Know The urinary tract includes the kidneys, ureters, bladder, and urethra. Kidneys filter blood, remove waste and produce urine (pee); ureters carry the urine from the kidneys to the bladder; and the bladder stores the urine until it is eliminated from the body through the urethra. A UTI can happen anywhere along this tract, but the lower part — the urethra and bladder — is most commonly involved. This is called cystitis. If the infection travels up the ureters to the kidneys, it's called pyelonephritis and is usually more serious. Most UTIs occur when bacteria infect the urinary tract, but some viruses also can cause an infection. Bacteria aren't normally found in pee, but they can easily enter the urinary tract from the skin around the anus. UTIs are highly treatable, but it's important to catch them early. Untreated UTIs can lead to kidney damage, especially in kids younger than 6. UTI symptoms include pain while peeing, frequent urination, low back pain or abdominal pain in the area of the bladder, fever, and foul-smelling urine that may look cloudy or contain blood. UTIs are treated with antibiotics. The antibiotic used and how long it must be taken depend on the type of bacteria causing the infection and how severe it is. Keep in Mind Most UTIs are cured within a week with proper medical treatment. Many UTIs can be prevented by changing infants' diapers frequently, encouraging kids to practice good hygiene, and instructing kids not to "hold it" when they have to pee because urine that remains in the bladder gives bacteria a good place to grow. Some UTIs are caused by a congenital condition called vesicoureteral reflux (VUR) that causes urine to flow from the bladder up the ureters and toward the kidneys. Kids with VUR should follow their doctor's treatment plan to prevent recurrent UTIs. All A to Z dictionary entries are regularly reviewed by KidsHealth medical experts. Back to Articles Related Articles Activity: Urinary System Do you know your urinary system? Label the parts of this important body system. Read More A to Z: Pyelonephritis Learn more about pyelonephritis and how it's treated. Read More Urinary Tract Infections A urinary tract infection (UTI) is one of the most common reasons that teens visit a doctor. Learn about the symptoms of UTIs, how they're treated, and more in this article. Read More First Aid: Pain With Urinating (Peeing) When it hurts to pee, a urinary tract infection (UTI) is usually to blame. But there are other causes. Here's what to do. Read More Your Urinary System You pee every day, but what makes it happen? Find out in this article for kids about the urinary system. Read More Why Am I Getting Urinary Tract Infections? Find out what the experts have to say! Read More Kidneys and Urinary Tract The kidneys perform several functions that are essential to health, the most important of which are to filter blood and produce urine. Read More Recurrent Urinary Tract Infections and Related Conditions Recurrent urinary tract infections can cause kidney damage if left untreated, especially in kids under age 6. Here's how to recognize the symptom of UTIs and get help for your child. Read More Urinary Tract Infections (UTIs) Urinary tract infections (UTIs) are common in kids. They're easy to treat and usually clear up in a week or so. Read More Your Kidneys You need at least one kidney to live. Find out why in this article for kids. Read More Kidneys and Urinary Tract The bean-shaped kidneys, each about the size of a child's fist, are essential to our health. Their most important role is to filter blood and produce urine. Read More Urine Tests Is your child having a urine culture or urinalysis performed? Find out why urine tests are performed, and what to expect when the doctor orders them. Read More Voiding Cystourethrogram (VCUG) A VCUG can help evaluate the bladder's size and shape, and look for problems, such as a blockage. It can also show whether pee is moving in the right direction. Read More Ultrasound: Renal (Kidneys, Ureters, Bladder) A renal ultrasound makes images of your child's kidneys, ureters, and bladder. Doctors may order this test if they suspect kidney damage, cysts, tumors, kidney stones, or complications from urinary tract infections. Read More Note: All information is for educational purposes only. For specific medical advice, diagnoses, and treatment, consult your doctor. © 1995-2021 KidsHealth®. All rights reserved. Images provided by The Nemours Foundation, iStock, Getty Images, Veer, Shutterstock, and Clipart.com.