Signs of a UTI in Babies
Medically reviewed by Dr. Michael Okonkwo, MD, FAAP · Board-Certified Neonatologist
Content reviewed against published AAP, CDC, AAP guidelines
Last reviewed:
If your baby has been diagnosed with or you suspect signs of a uti in babies, here is what the evidence says.
The short answer
UTIs (urinary tract infections) in babies can be tricky to spot because symptoms are often vague - fever without other cold symptoms, fussiness, poor feeding, or foul-smelling urine. If your baby has unexplained fever, especially if under 3 months, your pediatrician may test for a UTI. UTIs need antibiotic treatment to prevent kidney damage.
Key takeaways
- UTIs (urinary tract infections) in babies can be tricky to spot because symptoms are often vague - fever without other cold symptoms, fussiness, poor feeding, or foul-smelling urine. If your baby has unexplained fever, especially if under 3 months, your pediatrician may test for a UTI. UTIs need antibiotic treatment to prevent kidney damage.
- Usually normal when: Your baby's urine smells slightly stronger after starting a new food (like asparagus)
- Call your doctor if: Your baby under 3 months has any fever (100.4°F/38°C or higher)
- Varies by age — see the age-by-age breakdown below
“Fever itself is not an illness — rather, it is a sign or symptom that the body is fighting an infection. Fever stimulates certain defenses, such as the white blood cells, which attack and destroy invading bacteria.”
This is one of the most common questions parents ask. Searching for answers means you care.
What Parents Should Know
According to AAP, CDC guidelines, uTIs (urinary tract infections) in babies can be tricky to spot because symptoms are often vague - fever without other cold symptoms, fussiness, poor feeding, or foul-smelling urine. If your baby has unexplained fever, especially if under 3 months, your pediatrician may test for a UTI. UTIs need antibiotic treatment to prevent kidney damage. At 0-3 months, any fever in a baby under 3 months (100.4°F/38°C or higher) requires immediate medical evaluation, as UTIs are a common cause of fever in young infants. Your baby may seem generally unwell, feed poorly, or be unusually fussy. Because the signs are subtle, your doctor will likely test your baby's urine. Untreated UTIs can lead to serious kidney infection, so prompt diagnosis is critical. It is generally considered normal when your baby's urine smells slightly stronger after starting a new food (like asparagus). However, you should contact your pediatrician promptly if your baby under 3 months has any fever (100.4°F/38°C or higher).
Normal vs. Concerning
When to Seek Immediate Care
- Your baby under 3 months has any fever (100.4°F/38°C or higher)
- Your baby has a high fever (over 102°F/39°C) that doesn't improve with fever reducer
- Your baby is vomiting repeatedly and can't keep fluids down
- Your baby has very few wet diapers or shows signs of dehydration (sunken soft spot, no tears, dry lips)
- Your baby seems very unwell, is extremely lethargic, or has a weak cry
By Age
What to expect by age
0-3 months
Any fever in a baby under 3 months (100.4°F/38°C or higher) requires immediate medical evaluation, as UTIs are a common cause of fever in young infants. Your baby may seem generally unwell, feed poorly, or be unusually fussy. Because the signs are subtle, your doctor will likely test your baby's urine. Untreated UTIs can lead to serious kidney infection, so prompt diagnosis is critical.
3-6 months
UTI symptoms at this age may include fever without runny nose or cough, irritability, vomiting, or poor feeding. You might notice your baby cries more during diaper changes or has foul-smelling urine. Girls are at higher risk than boys. If your baby has a fever and your pediatrician can't find an obvious source (like an ear infection), they'll likely collect a urine sample.
6-12 months
Babies with UTIs may have fever, fussiness, loss of appetite, or vomiting. Some babies cry when urinating, though this is not always obvious. Urine may smell stronger than usual or look cloudy. If your baby has a fever lasting more than 24 hours without clear cold symptoms, mention this to your doctor - they may want to rule out a UTI.
12-24 months
Toddlers may start to show more classic UTI symptoms like crying when peeing, holding their diaper area, or peeing more or less frequently than usual. Fever, abdominal pain, or new-onset bedwetting (if previously dry) can also be signs. If your toddler is potty training, accidents combined with fever could indicate a UTI. Diagnosis requires a urine test.
2 years+
Older toddlers can sometimes tell you it hurts to pee or that their belly hurts. Look for frequent urination, accidents in a previously toilet-trained child, strong-smelling or cloudy urine, or fever. Some children have UTIs without fever. If you suspect a UTI, contact your pediatrician - they'll test the urine and prescribe antibiotics if needed.
What to Tell Your Pediatrician
- Describe when you first noticed signs of a uti in babies and how it has changed over time.
- Note your baby's current age and which age-specific patterns you are seeing.
- Mention if your baby has unexplained fussiness or seems uncomfortable during diaper changes.
- Mention if your baby's urine has a consistently foul smell.
- Bring a list of any questions or observations you want to discuss at the appointment.
What Should You Do?
When to take action
- Your baby's urine smells slightly stronger after starting a new food (like asparagus)
- Your baby cries briefly during a diaper change but is otherwise happy
- Your baby has a mild cold with low-grade fever and typical cold symptoms (runny nose, cough)
- Your baby is feeding well, having regular wet diapers, and seems comfortable
- Your baby has unexplained fussiness or seems uncomfortable during diaper changes
- Your baby's urine has a consistently foul smell
- Your baby has had one UTI before (may need follow-up imaging or evaluation)
- Your baby has a low-grade fever for more than 24 hours with no clear source
- Your baby under 3 months has any fever (100.4°F/38°C or higher)
- Your baby has a high fever (over 102°F/39°C) that doesn't improve with fever reducer
- Your baby is vomiting repeatedly and can't keep fluids down
- Your baby has very few wet diapers or shows signs of dehydration (sunken soft spot, no tears, dry lips)
- Your baby seems very unwell, is extremely lethargic, or has a weak cry
What You Can Do at Home
- Keep track of when you notice signs of a uti in babies — noting the time of day, duration, and any triggers can help your pediatrician.
- Remember that your baby's urine smells slightly stronger after starting a new food (like asparagus) — this is generally within the range of normal.
- At 0-3 months, focus on observation rather than intervention unless your pediatrician advises otherwise.
- Follow any care instructions from your pediatrician. Keep a written log of symptoms to bring to appointments.
- While monitoring at home, seek immediate care if your baby under 3 months has any fever (100.4°F/38°C or higher).
Related Resources
Fever Decision Tree
Step-by-step guidance for evaluating your baby's fever by age and temperature.
Excessive Crying Triage
Determine whether crying patterns need medical attention.
Month-by-Month Development
Detailed monthly development guides from birth through 24 months.
When to Call the Doctor
General guide on when to call the pediatrician, visit urgent care, or go to the ER.
Frequently asked questions
Is signs of a uti in babies normal?
When should I call the doctor about signs of a uti in babies?
When is signs of a uti in babies normal?
What causes signs of a uti in babies?
What should I mention to my pediatrician about signs of a uti in babies?
Is signs of a uti in babies normal at 0-3 months?
Is signs of a uti in babies normal at 3-6 months?
Should I go to the ER for signs of a uti in babies?
Does signs of a uti in babies go away on its own?
References
Doctor Visit Checklist
Bring this checklist to your next pediatrician visit to discuss Signs of a UTI in Babies.
Things to mention
- Describe when you first noticed signs of a uti in babies and how it has changed over time.
- Note your baby's current age and which age-specific patterns you are seeing.
- Mention if your baby has unexplained fussiness or seems uncomfortable during diaper changes.
- Mention if your baby's urine has a consistently foul smell.
- Bring a list of any questions or observations you want to discuss at the appointment.
Observations to share
- Your baby has unexplained fussiness or seems uncomfortable during diaper changes
- Your baby's urine has a consistently foul smell
- Your baby has had one UTI before (may need follow-up imaging or evaluation)
Urgent signs to report immediately
- Your baby under 3 months has any fever (100.4°F/38°C or higher)
- Your baby has a high fever (over 102°F/39°C) that doesn't improve with fever reducer
- Your baby is vomiting repeatedly and can't keep fluids down
My notes
From ismybabyalright.com — free, evidence-based baby health guides
All content follows our editorial policy and is reviewed against published clinical guidelines.
2,705 evidence-based guides6 authoritative medical sources5 medical advisory board members
Related Resources
Bottom line
Most cases of signs of a uti in babies are normal. Talk to your pediatrician if your baby under 3 months has any fever (100.4°f/38°c or higher).
Trust your instincts. If something feels wrong, reach out to your pediatrician. Worrying about your baby means you care — that is a good thing.
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