Urinary Tract Infections in Children: Symptoms, Testing, and When to Seek Care

What is a UTI?

A UTI happens when bacteria—usually germs that normally live in the bowel—get into the urinary tract. There are two main types:

• Bladder infection (cystitis): The infection stays in the bladder. It usually causes burning, frequent urination, and belly discomfort, often without fever.
• Kidney infection (pyelonephritis): The infection reaches one or both kidneys. It often causes fever and a sicker-looking child, and it is the type that can, in some cases, lead to kidney scarring.

Symptoms can overlap, especially in babies. Fever alone cannot tell you whether an infection involves the kidneys.

Symptoms to watch for

The signs of a UTI depend a lot on your child's age.

Babies and toddlers

Children under about 2 years often cannot tell you what is wrong, and the signs may be vague. Watch for:

• Fever with no obvious cause
• Poor feeding or not gaining weight
• Vomiting, fussiness, or irritability
• Unusual sleepiness
• Foul-smelling urine

In this age group, an unexplained fever may be the only sign of a UTI. This is one of the most important things for parents to know. Having cold symptoms does not completely rule out a UTI.

A child who is difficult to wake needs emergency evaluation, not just a routine appointment.

Older, potty-trained children

Older children can usually point to the problem. Watch for:

• Pain or burning when urinating
• Needing to urinate often or urgently
• New daytime wetting or bedwetting after being dry
• Belly pain, or pain in the side or back
• Cloudy or bad-smelling urine
• Fever, which can suggest that the kidneys are involved

Cloudy or strong-smelling urine alone does not prove there is an infection. Your child's symptoms and urine test results need to be considered together.

When to call the doctor

Contact your child's pediatrician promptly when you suspect a UTI, especially for:

• A young child with a fever without a clear cause, particularly when it lasts more than a day or two
• Pain or burning with urination, or new wetting accidents
• Back or side pain with fever
• Poor feeding, vomiting, or an infant who seems unwell

When to seek urgent or emergency care

Seek urgent medical evaluation if your child has a high fever with shaking chills, repeatedly vomits and cannot keep fluids down, has signs of dehydration, or looks very unwell.

Go to the emergency department for extreme sleepiness, difficulty waking, poor responsiveness, or a seriously ill appearance. For a possible life-threatening emergency, call 911.

Do not wait for a routine appointment when your child is getting worse. Prompt treatment helps reduce the risk of complications.

How a UTI is diagnosed

A UTI cannot be diagnosed from symptoms alone—a urine test is needed. The doctor will usually:

• Test the urine with a dipstick and/or look at it under a microscope for signs of infection.
• Send a urine culture to grow and identify the bacteria and help determine which antibiotic will work best. Culture results usually take 1 to 2 days.

How the urine is collected matters. In babies and children who are not potty-trained, a small catheter—a thin tube—often provides a more reliable sample than a stick-on bag. Bag samples are easily contaminated by bacteria on the skin.

A bag sample may sometimes be used for an initial screening test, but a positive bag culture alone should not be used to confirm a UTI. A more reliable sample is needed. In older children, a properly collected clean-catch midstream sample is usually enough.

Whenever possible, collect urine before starting antibiotics. Antibiotics can make a culture harder to interpret. However, urgent treatment should not be delayed in a seriously ill child if a urine sample cannot be obtained promptly.

How a UTI is treated

• Antibiotics are the main treatment. The doctor often starts an antibiotic based on the initial findings, then adjusts the plan once culture results return.
• Most children can be treated at home with oral antibiotics. Very young infants, children who are seriously ill, or those who cannot keep fluids or medicine down may need hospital care and intravenous antibiotics.
• Give the antibiotic for the full prescribed duration unless your clinician changes the plan. Treatment may last several days to about 10 days, depending on the infection and your child's age. If the culture does not confirm a UTI, the clinician may recommend stopping the antibiotic.
• Symptoms should begin improving within 48 hours. Contact the doctor if fever or other symptoms are not improving within 48 hours of starting treatment—or sooner if your child is getting worse. The antibiotic may need to change, or further evaluation may be needed.
• Fever and pain relievers such as acetaminophen can help your child feel more comfortable when used appropriately for age and weight.

See our Fever in Children guide for comfort measures and weight-based medication dosing tables.

Sometimes, especially after a first kidney infection in a young child or after repeated infections, the doctor may recommend an ultrasound of the kidneys and bladder or other imaging. The need for testing depends on your child's age, response to treatment, infection history, and other findings.

Preventing future UTIs

Some children get UTIs more than once. These everyday steps can help lower the risk:

• Treat and prevent constipation. A full bowel can interfere with bladder emptying. Our Constipation in Children guide explains what to watch for.
• Encourage regular, complete bladder emptying and discourage holding urine for long periods.
• Offer enough age-appropriate fluids throughout the day. For young babies, continue breast milk or formula rather than adding extra water unless a clinician advises it.
• Wipe front to back after using the toilet.
• In uncircumcised boys, use gentle routine cleaning. Never force the foreskin back. Clean the outside until it retracts naturally.

What about cranberry juice or supplements?

Research suggests that cranberry products may reduce repeat UTIs in some children, but products and doses vary, and there is no established standard dose for children. Ask your child's clinician before using one for prevention.

Cranberry does not treat an active UTI and must not replace urine testing or prescribed antibiotics.

What about daily preventive antibiotics?

These are not routinely recommended after a first UTI. They may be considered for selected children with repeated infections or certain urinary tract problems. The possible benefits need to be weighed against side effects and antibiotic resistance with your child's clinician.

The bottom line

UTIs in children are common and very treatable.

• An unexplained fever may be the only sign in a baby or toddler.
• A properly collected urine sample matters; symptoms alone cannot confirm a UTI.
• Urine should be collected before antibiotics when possible, without delaying urgent treatment for a seriously ill child.
• Follow the antibiotic plan and check back if symptoms are not improving within 48 hours—or sooner if your child worsens.
• Addressing constipation and avoiding prolonged urine holding can help prevent repeat infections.

With prompt care, the vast majority of children do very well. If you are worried about your child, contact your pediatrician.