My Baby Has a Fever That Won't Go Away
Medically reviewed by Dr. Michael Okonkwo, MD, FAAP · Board-Certified Neonatologist
Content reviewed against published AAP, AAP, Mayo Clinic guidelines
Last reviewed:
If your baby has been diagnosed with or you suspect has a fever that won't go away, here is what the evidence says.
The short answer
Most fevers in babies and toddlers are caused by viral infections and resolve within 3-5 days. A fever that lasts longer than 3 days, returns after seeming to resolve, or is accompanied by worsening symptoms warrants medical evaluation. The most important thing is how your baby looks and acts - a child who is alert and drinking well with a fever is generally less concerning than one who is listless, regardless of the temperature.
Key takeaways
- Most fevers in babies and toddlers are caused by viral infections and resolve within 3-5 days. A fever that lasts longer than 3 days, returns after seeming to resolve, or is accompanied by worsening symptoms warrants medical evaluation. The most important thing is how your baby looks and acts - a child who is alert and drinking well with a fever is generally less concerning than one who is listless, regardless of the temperature.
- Usually normal when: A fever lasting 2-3 days during an obvious viral illness (cold, stomach bug) with your child drinking well and having periods of normal activity
- Call your doctor if: Any fever in a baby under 3 months old requires immediate medical evaluation; a fever above 104°F (40°C) in any child, or a fever lasting 5 or more days with rash, red eyes, swollen hands/feet, or red cracked lips (possible Kawasaki disease) needs urgent assessment
- 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.”
Thousands of parents search for this exact thing. You are not alone.
What Parents Should Know
According to AAP, Mayo Clinic guidelines, most fevers in babies and toddlers are caused by viral infections and resolve within 3-5 days. A fever that lasts longer than 3 days, returns after seeming to resolve, or is accompanied by worsening symptoms warrants medical evaluation. The most important thing is how your baby looks and acts - a child who is alert and drinking well with a fever is generally less concerning than one who is listless, regardless of the temperature. At 0-3 months, any fever (rectal temperature of 100.4°F / 38°C or higher) in a baby under 3 months requires immediate medical evaluation, regardless of how well the baby looks. Young infants have immature immune systems and can develop serious bacterial infections (urinary tract infection, meningitis, bloodstream infection) with minimal symptoms. Your doctor will likely perform blood tests, urine tests, and possibly a lumbar puncture to identify the cause. Do not give fever-reducing medication before seeking evaluation, as it may mask symptoms. It is generally considered normal when a fever lasting 2-3 days during an obvious viral illness (cold, stomach bug) with your child drinking well and having periods of normal activity. However, you should contact your pediatrician promptly if any fever in a baby under 3 months old requires immediate medical evaluation; a fever above 104°F (40°C) in any child, or a fever lasting 5 or more days with rash, red eyes, swollen hands/feet, or red cracked lips (possible Kawasaki disease) needs urgent assessment.
Normal vs. Concerning
By Age
What to expect by age
0-3 months
Any fever (rectal temperature of 100.4°F / 38°C or higher) in a baby under 3 months requires immediate medical evaluation, regardless of how well the baby looks. Young infants have immature immune systems and can develop serious bacterial infections (urinary tract infection, meningitis, bloodstream infection) with minimal symptoms. Your doctor will likely perform blood tests, urine tests, and possibly a lumbar puncture to identify the cause. Do not give fever-reducing medication before seeking evaluation, as it may mask symptoms.
3-6 months
A fever in this age group is commonly caused by viral infections, though bacterial infections still need to be considered. If the fever lasts more than 2-3 days, is above 102°F (38.9°C), or your baby appears unwell (poor feeding, excessive fussiness, decreased responsiveness), contact your pediatrician. Roseola, a common viral illness, classically causes 3-5 days of high fever followed by a rash once the fever breaks. UTIs are a common hidden cause of unexplained fever at this age.
6-24 months
Viral infections are the most common cause of fever, and children in daycare may have frequent fevers. A typical viral fever lasts 3-5 days. Post-vaccination fevers usually resolve within 24-48 hours. Fevers lasting more than 5 days, or a fever that resolves then returns, warrant evaluation to look for bacterial complications like ear infections, pneumonia, or urinary tract infections. Teething may cause a very mild temperature elevation but does not cause true fevers above 100.4°F.
2-3 years
Toddlers can have fevers lasting up to a week with certain viral illnesses like adenovirus, influenza, or hand-foot-and-mouth disease. Focus on how your child is acting: drinking fluids, making urine, and being at least periodically alert and interactive are reassuring signs. A fever lasting more than 5-7 days, or a fever above 104°F (40°C) that does not come down with appropriate doses of acetaminophen or ibuprofen, should be evaluated. Persistent high fever lasting 5 or more days may indicate Kawasaki disease, which requires specific treatment.
What to Tell Your Pediatrician
- Describe when you first noticed has a fever that won't go away and how it has changed over time.
- Note your baby's current age and which age-specific patterns you are seeing.
- Mention if the fever has lasted more than 3-5 days without improvement or a clear cause.
- Mention if the fever resolved for 24 hours then returned, which may indicate a secondary bacterial infection.
- Bring a list of any questions or observations you want to discuss at the appointment.
What Should You Do?
When to take action
- A fever lasting 2-3 days during an obvious viral illness (cold, stomach bug) with your child drinking well and having periods of normal activity
- A mild fever for 1-2 days after vaccinations
- The fever responds to acetaminophen or ibuprofen (in children over 6 months) and your child perks up when the temperature comes down
- Your child is producing tears when crying and making wet diapers regularly
- The fever has lasted more than 3-5 days without improvement or a clear cause
- The fever resolved for 24 hours then returned, which may indicate a secondary bacterial infection
- Your child has a fever along with ear pain, pulling at ears, persistent cough, or painful urination
- Any fever in a baby under 3 months old requires immediate medical evaluation; a fever above 104°F (40°C) in any child, or a fever lasting 5 or more days with rash, red eyes, swollen hands/feet, or red cracked lips (possible Kawasaki disease) needs urgent assessment
- Your child has a fever with stiff neck, severe headache, confusion, difficulty breathing, purple spots on the skin, persistent vomiting, or appears extremely ill or unresponsive - seek emergency care immediately
What You Can Do at Home
- Keep track of when you notice has a fever that won't go away — noting the time of day, duration, and any triggers can help your pediatrician.
- Remember that a fever lasting 2-3 days during an obvious viral illness (cold, stomach bug) with your child drinking well and having periods of normal activity — 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 any fever in a baby under 3 months old requires immediate medical evaluation; a fever above 104°F (40°C) in any child, or a fever lasting 5 or more days with rash, red eyes, swollen hands/feet, or red cracked lips (possible Kawasaki disease) needs urgent assessment.
Related Resources
Fever Decision Tree
Step-by-step guidance for evaluating your baby's fever by age and temperature.
Medicine Dosage Calculator
Calculate correct Tylenol and Motrin doses by your baby's weight.
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 has a fever that won't go away normal?
When should I call the doctor about has a fever that won't go away?
When is has a fever that won't go away normal?
What causes has a fever that won't go away?
What should I mention to my pediatrician about has a fever that won't go away?
Is has a fever that won't go away normal at 0-3 months?
Is has a fever that won't go away normal at 3-6 months?
Should I go to the ER for has a fever that won't go away?
Does has a fever that won't go away go away on its own?
References
- [1]Sullivan JE, Farrar HC. Fever and Antipyretic Use in Children. Pediatrics, 2011. AAP
- [2]HealthyChildren.org. Fever Without Fear: Information for Parents. AAP
- [3]Mayo Clinic. Fever in Children: When to Seek Medical Attention. Mayo Clinic
Doctor Visit Checklist
Bring this checklist to your next pediatrician visit to discuss My Baby Has a Fever That Won't Go Away.
Things to mention
- Describe when you first noticed has a fever that won't go away and how it has changed over time.
- Note your baby's current age and which age-specific patterns you are seeing.
- Mention if the fever has lasted more than 3-5 days without improvement or a clear cause.
- Mention if the fever resolved for 24 hours then returned, which may indicate a secondary bacterial infection.
- Bring a list of any questions or observations you want to discuss at the appointment.
Observations to share
- The fever has lasted more than 3-5 days without improvement or a clear cause
- The fever resolved for 24 hours then returned, which may indicate a secondary bacterial infection
- Your child has a fever along with ear pain, pulling at ears, persistent cough, or painful urination
Urgent signs to report immediately
- Any fever in a baby under 3 months old requires immediate medical evaluation; a fever above 104°F (40°C) in any child, or a fever lasting 5 or more days with rash, red eyes, swollen hands/feet, or red cracked lips (possible Kawasaki disease) needs urgent assessment
- Your child has a fever with stiff neck, severe headache, confusion, difficulty breathing, purple spots on the skin, persistent vomiting, or appears extremely ill or unresponsive - seek emergency care immediately
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 has a fever that won't go away are normal. Talk to your pediatrician if any fever in a baby under 3 months old requires immediate medical evaluation; a fever above 104°f (40°c) in any child, or a fever lasting 5 or more days with rash, red eyes, swollen hands/feet, or red cracked lips (possible kawasaki disease) needs urgent assessment.
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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