Your child has a fever with no obvious cause. No runny nose, no ear pain — but the fever persists. Could it be a urinary tract infection?

A urinary tract infection (UTI) is one of the most common bacterial infections in children, and it is especially important to catch it in babies — where symptoms can be vague and hard to interpret.

What Is a Urinary Tract Infection?

A UTI occurs when bacteria enter the urinary tract and begin to multiply. The infection can affect:

Lower urinary tract (cystitis) – bacteria in the bladder. Most common and least serious.
Upper urinary tract (pyelonephritis) – bacteria have reached the kidneys. More serious and requires prompt treatment.

The most common bacterium is E. coli, which normally lives in the gut. Girls are affected more often than boys because the urethra is shorter and closer to the anal opening.

Symptoms Vary With Age

The symptoms of a UTI look very different depending on the child's age. This is one reason the infection can be difficult to spot in younger children.

Babies Under 1 Year

In babies, symptoms are often non-specific:

Fever – often the only clear sign, can be high
Irritability and restlessness – the baby is unsettled without obvious cause
Poor appetite – refusing breast or bottle
Vomiting – can resemble a stomach bug
Poor weight gain – with repeated or prolonged infections
Jaundice – in newborns this can be a sign
Foul-smelling urine – can be difficult to detect in a diaper

In babies under 3 months with a fever, always contact a doctor promptly. Fever without an obvious cause in very young babies is a reason to check the urine.

Toddlers Ages 1–3

In toddlers, symptoms may become more apparent, but the child cannot always explain what hurts:

Fever – can be high or low
Holding their abdomen or groin – a sign of pain
Changed urination pattern – urinating more frequently, in small amounts
Crying when urinating – the child shows discomfort
Foul-smelling or cloudy urine
Regression in potty training – a child who was dry starts having accidents again

Older Children (3+ Years)

Older children can describe their symptoms more clearly:

Pain or burning when urinating
Frequent urge to urinate – going often but passing very little each time
Pain in the abdomen or lower back
Blood in the urine – can make urine appear pink or red
Foul-smelling urine
Fever with a kidney infection

How Is a Urine Sample Collected in Children?

To make a diagnosis, the doctor needs a urine sample. The method depends on the child's age.

Babies (in diapers)

Bag specimen – a small plastic bag is attached around the child's genital area. Easy method, but can give false positive results due to contamination from skin and stool
Clean midstream sample – if the bag specimen shows signs of infection, a cleaner sample is usually collected
Catheter sample – a doctor inserts a thin tube into the bladder. Gives the most reliable sample in babies

Toddlers and Older Children

Midstream urine sample – the child urinates into a cup after washing. The first part of the stream is let out, and the middle portion is collected
Urine dipstick – a quick test that shows whether there are signs of infection. Confirmed with a sample sent to the laboratory

Tip for collecting a urine sample from a toddler: Bring a clean cup to the doctor's office. Let the child drink plenty of fluids beforehand. Be patient — it may take time. Some children find it easier to urinate into a cup in the bathtub.

Treatment

A UTI is treated with antibiotics. The type and duration depend on whether the infection is in the lower or upper urinary tract.

Lower UTI (Cystitis)

Antibiotics for 3–5 days – usually tablets or liquid suspension
Improvement within 1–2 days – symptoms should ease quickly
Complete the full course – even if your child feels better

Upper UTI (Pyelonephritis)

Antibiotics for 7–10 days – a longer course than for cystitis
Hospital admission may be necessary for babies under 3 months or with severe illness
Intravenous antibiotics – given directly into the bloodstream in serious cases

Pain Relief

Acetaminophen (paracetamol/Tylenol) for fever and pain – follow age-appropriate dosing
Plenty of fluids – helps flush bacteria from the bladder
Frequent diaper changes in babies

Child being examined by a doctor

Follow-Up After Infection

According to current pediatric guidelines (AAP), the following is recommended:

Urine test after completing treatment – to confirm the infection has cleared
Kidney ultrasound – recommended after the first UTI in children under 2 years, and with repeated infections in older children
VCUG (voiding cystourethrogram) – a specialized X-ray examination that can detect vesicoureteral reflux (backflow of urine to the kidneys). Performed in selected children

The doctor will assess whether the child needs further evaluation based on age, severity, and whether there have been multiple infections.

When Should You Contact a Doctor?

Call your pediatrician or seek urgent care if:

A baby under 3 months has a fever
Your child has a fever without obvious cause for more than 24 hours
Your child cries or shows pain when urinating
You see blood in the urine
Your child has pain in the flank (side of the back)
Your child is lethargic and drinking poorly

Call emergency services (911 / your local emergency number) if your child is very lethargic, difficult to wake, has a high fever that does not respond to acetaminophen, or shows signs of dehydration (dry diapers, sunken eyes, floppiness).

Preventing Urinary Tract Infections

You can reduce the risk of recurrent infections:

Good hygiene – wipe front to back after toileting (for girls)
Frequent diaper changes – change diapers often to avoid bacterial growth
Enough fluids – make sure your child drinks enough throughout the day
Do not hold it in – encourage your child to urinate regularly and not to hold on for too long
Avoid constipation – constipation can press on the bladder and cause incomplete emptying
Cotton underwear – choose breathable materials close to the skin

Happy child drinking water

Frequently Asked Questions

Can babies get UTIs?

Yes, babies can absolutely get urinary tract infections. In very young babies, fever is often the only sign. Boys have a slightly higher risk than girls during the first year of life.

Is a UTI dangerous for children?

A lower UTI (cystitis) is usually harmless with proper treatment. An upper UTI (pyelonephritis) is more serious because it can damage the kidneys if not treated promptly.

Can a UTI cause fever with no other symptoms?

Yes, especially in babies. Fever without an obvious source is a common reason to check the urine. It is important to test urine if your child has unexplained fever.

How long does it take for antibiotics to work?

Your child should start to feel better within 24–48 hours of starting antibiotics. If there is no improvement within 48 hours, contact your doctor again. The bacteria may be resistant to the medication and the course may need to be changed.

Can my child go to daycare with a UTI?

UTIs do not spread between children. Your child can return to daycare as soon as they feel well enough, provided they are fever-free and have started antibiotics.

Urinary Tract Infection in Children: Symptoms and Treatment