Urinary tract infections (UTIs) can occur when bacteria get into the bladder or the kidneys. These bacteria are common on the skin around the anus. They can also be present near the vagina.

Some factors make it easier for bacteria to enter or stay in the urinary tract, such as:

• Vesicoureteral reflux in which urine flow backs up from the bladder into the ureters and kidneys.
• Brain or nervous system illnesses (such as myelomeningocele or spinal cord injury).
• Bubble baths or tight-fitting clothes (girls).
• Changes or birth defects in the structure of the urinary tract.
• Not urinating often enough during the day.
• Wiping from back (near the anus) to front after going to the bathroom. In girls, this can bring bacteria to the opening where the urine comes out.

UTIs are more common in girls. This may occur as children begin toilet training around 3 years of age. Boys who are not circumcised have a slightly higher risk of UTIs before age 1.

Young children with UTIs may have a fever, poor appetite, vomiting, or no symptoms at all.

Most UTIs in children only involve the bladder. It may spread to the kidneys.

Symptoms of a bladder infection in children include:

• Blood in the urine
• Cloudy urine
• Foul or strong urine odor
• Frequent or urgent need to urinate
• General ill feeling (malaise)
• Pain or burning with urination
• Pressure or pain in the lower pelvis or lower back
• Wetting problems after the child has been toilet trained

Signs that the infection may have spread to the kidneys include:

• Chills with shaking
• Fever
• Flushed, warm, or reddened skin
• Nausea and vomiting
• Pain in the side (flank) or back
• Severe pain in the belly area

A urine sample is needed to diagnose a UTI in a child. The sample is examined under a microscope and sent to a lab for a urine culture.

It may be hard to get a urine sample in a child who is not toilet trained. The test cannot be done using a wet diaper.

Ways to collect a urine sample in a very young child include:

• Urine collection bag -- A special plastic bag is placed over the child's penis or vagina to catch the urine. This is not the best method because the sample may become contaminated by bacteria that are not in the urine.
• Catheterized specimen urine culture -- A plastic tube (catheter) placed into the tip of the penis in boys, or straight into the urethra in girls, collects urine right from the bladder.
• Suprapubic urine collection -- A needle is placed through the skin of the lower abdomen and muscles into the bladder. It is used to collect urine.

Imaging may be done to check for any anatomical abnormalities or to check kidney structure and function, including:

• Ultrasound
• X-ray taken while the child is urinating (voiding cystourethrogram)

Your health care provider will consider many things when deciding if and when a special study is needed, including:

• The child's age and history of other UTIs (infants and younger children usually need follow-up tests)
• The severity of the infection and how well it responds to treatment
• Other medical problems or physical defects the child may have

In children, UTIs should be treated quickly with antibiotics to protect the kidneys. Any child under 6 months old or who has other complications should see a specialist right away.

Younger infants will most often need to stay in the hospital and be given antibiotics through a vein. Older infants and children are treated with antibiotics by mouth. If this is not possible, they may need to get treated in the hospital.

Your child should drink plenty of fluids when being treated for a UTI.

Some children may be treated with antibiotics for periods as long as 6 months to 2 years. This treatment is more likely when the child has had repeat infections or high grade vesicoureteral reflux.

After antibiotics are finished, your child's provider may ask you to bring your child back to do another urine test. This may be needed to make sure that bacteria are no longer in the bladder.

Most children are cured with proper treatment. Most of the time, repeat infections can be prevented.

Repeated infections that involve the kidneys can lead to long-term damage to the kidneys.

Contact your provider if your child's symptoms continue after treatment, or come back more than twice in 6 months or your child has:

• Back pain or flank pain
• Bad-smelling, bloody, or discolored urine
• Fever of 102.2°F (39°C) in infants for longer than 24 hours
• Low back pain or abdominal pain below the belly button
• Fever that does not go away
• Very frequent urination, or need to urinate many times during the night
• Vomiting

Things you can do to prevent UTIs include:

• Avoid giving your child bubble baths.
• Have your child wear loose-fitting underpants and clothing.
• Increase your child's intake of fluids.
• Keep your child's genital area clean to prevent bacteria from entering through the urethra.
• Teach your child to go the bathroom several times every day.
• Teach your child to wipe the genital area from front to back to reduce the spread of bacteria.

To prevent recurrent UTIs, the provider may recommend low-dose antibiotics after the first symptoms have gone away.

UTI - children; Cystitis - children; Bladder infection - children; Kidney infection - children; Pyelonephritis - children

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Jerardi KE and Jackson EC. Urinary tract infections. In: Kliegman RM, St. Geme JW, Blum NJ, Shah SS, Tasker RC, Wilson KM. eds. Nelson Textbook of Pediatrics. 21st ed. Philadelphia, PA: Elsevier; 2020:chap 553.

Mattoo TK, Shaikh N, Nelson CP. Contemporary management of urinary tract infection in children. Pediatrics. 2021;147(2):e2020012138.PMID: 33479164 pubmed.ncbi.nlm.nih.gov/33479164/.

Sobel JD, Brown P. Urinary tract infections. In: Bennett JE, Dolin R, Blaser MJ eds. Mandell, Douglas and Bennett's Principles and Practice of Infectious Diseases. 9th ed. Philadelphia, PA: Elsevier; 2020:chap 72.

Veauthier B, Miller MV. Urinary tract infections in young children and infants: common questions and answers. Am Fam Physician. 2020;102(5):278-285. PMID: 32866365 pubmed.ncbi.nlm.nih.gov/32866365/.

Updated by: Charles I. Schwartz, MD, FAAP, Clinical Assistant Professor of Pediatrics, Perelman School of Medicine at the University of Pennsylvania, General Pediatrician at PennCare for Kids, Phoenixville, PA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.