Few things spike a parent’s anxiety like a thermometer that won’t come down. You’ve given fever-reducing medication, you’ve done a lukewarm bath, you’ve checked again, and the number is still high. Maybe it’s been going for hours, maybe days. The pediatrician’s office is closed. You’re standing in the kitchen at 1 a.m. with your phone, trying to figure out whether to drive to the ER or wait it out.
Here’s the most important thing this article will tell you: with pediatric fever, the temperature number itself is rarely the most important factor. How your child looks, how they’re acting, how old they are, and how long the fever has lasted matter more than whether the thermometer reads 102 or 104. A child who is alert, drinking, and engaging at 103°F is in a different situation than a child who is limp and unresponsive at 101°F.
This article walks through what counts as a fever at each age, what “not going down” actually means in pediatric medicine, the warning signs that matter more than the number, and the conditions that persistent high fever can signal. If your child is symptomatic now, skip to the red-flag section first.
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Any of these signs in a child with fever, regardless of the exact temperature number, means don’t wait. Call 911 if severe, or come straight to ER of Dallas:
Critical age-based rule:
- ANY fever of 100.4°F (38°C) or higher in an infant under 3 months, regardless of how the child looks. No exceptions. This is an immediate ER visit.
Behavior and responsiveness warning signs:
- Lethargy, unusually sleepy, hard to wake up, not responding normally
- Limp or floppy body tone
- Inconsolable crying, or a weaker/quieter cry than usual (infants)
- Confusion, disorientation, or unusual behavior
- Not making eye contact, not interacting with familiar people or toys
- A child who just “doesn’t seem right” to you
Breathing and circulation warning signs:
- Difficulty breathing, fast breathing, retractions (skin pulling in around ribs or above collarbones), or grunting
- Blue, gray, or unusually pale lips, face, or skin
- Cold, mottled, or grayish hands and feet despite the fever
- Capillary refill longer than 2 seconds (press a fingernail, color should return quickly)
Neurologic warning signs:
- Stiff neck or pain when bending the head forward
- Severe headache (in children old enough to describe it)
- Sensitivity to light
- A rash that doesn’t blanch (fade) when pressed with a clear glass, possible meningococcal infection
- Bulging soft spot (fontanelle) in an infant
- Seizure of any kind, even a brief one
- Repeated vomiting along with high fever and lethargy
Dehydration with fever:
- No wet diaper in 6+ hours (infant) or no urination in 8–12 hours (older child)
- Dry mouth, no tears when crying, sunken eyes, sunken soft spot
- Refusing all fluids
Persistent fever red flags:
- Fever lasting more than 5 days, regardless of how the child appears, raises specific clinical concerns including Kawasaki disease
- Fever in a child with a known chronic medical condition (sickle cell, immunodeficiency, cancer treatment, organ transplant, congenital heart disease)
- Fever in a child on chemotherapy or long-term steroids
- Fever after recent international travel, some travel-related infections can be severe
- Fever with severe abdominal pain
- Fever combined with a new rash, swelling of hands or feet, red eyes without discharge, red cracked lips, or swollen lymph nodes, possible Kawasaki disease in young children
- Recent COVID-19 infection (within 6 weeks) with new fever and rash, abdominal pain, or other multi-organ symptoms, possible MIS-C
What “Fever” Actually Means by Age
Different ages use different thresholds. Using a reliable thermometer matters, rectal temperature is most accurate in infants; oral or temporal artery (forehead) thermometers work for older children; ear thermometers are reasonable in children over 6 months.
| Age | Fever Threshold | Threshold for Urgent Evaluation |
| Under 3 months | Any temp at or above 100.4°F (38°C), rectal | 🚨 ER immediately, no exceptions |
| 3–6 months | Temp at or above 100.4°F (38°C) | Call pediatrician or come to ER for evaluation, especially if temp is 102°F+ or other signs are present |
| Over 6 months | Temp at or above 100.4°F (38°C) | How the child looks and acts matters more than the number; specific warning signs trigger ER (see red flag list) |
The under-3-months rule is the most important threshold in pediatric medicine. Newborns and young infants haven’t developed full immune responses, so even mild-seeming fevers can signal serious infection that’s otherwise hidden. This rule is not flexible, it applies whether the infant looks happy and content or sleepy and fussy.
What “Not Going Down” Actually Means
When parents say a fever “isn’t going down,” they often mean one of two different things, and the distinction matters.
Meaning 1: Fever-reducing medication isn’t bringing the temperature to normal. Fever-reducing medications, prescribed and dosed by a pediatrician, typically lower a child’s fever by 2–3 degrees within 30–60 minutes. They don’t always bring the temperature all the way to 98.6°F, and they’re not designed to. A child whose 103°F fever comes down to 100°F after medication is responding normally. A child whose fever doesn’t come down at all may have a higher underlying infection load, or it may be a sign that the original measurement was inaccurate. Either way, lack of response to fever reducers is a reason to be evaluated, not necessarily an emergency on its own.
Meaning 2: The fever has been persistent over days. A fever that’s been going for several days, even if it goes up and down within a day, deserves evaluation. Most viral illnesses resolve within 3–5 days. A fever that persists beyond day 5, or one that’s getting higher instead of lower over the course of an illness, raises specific clinical concerns (see the serious causes section below).
What we tell parents in the ER: the goal of treating fever is the child’s comfort, not the thermometer reading. A child who feels okay at 101°F doesn’t need aggressive treatment. A child who feels miserable at 100°F may benefit from comfort measures and fever reducers. Treat the child, not the number, but watch for the warning signs that mean evaluation is needed.
Why the Temperature Number Isn’t the Most Important Thing
It’s natural to focus on the number on the thermometer, it’s the data point that feels most concrete. But emergency physicians evaluating children with fever pay much more attention to how the child looks and acts than to the exact temperature. A few examples:
- A child with a temp of 104°F who is alert, drinking fluids, playing with a toy, and making eye contact is generally less worrying than a child with a temp of 101°F who is lethargic, refusing to drink, and unable to be engaged.
- A child whose fever responds well to fever-reducing medication and who looks much better afterward is showing a reassuring response.
- A child whose fever doesn’t respond at all, OR who looks just as ill after the temperature comes down, is showing a more concerning pattern.
This is one reason we encourage parents to bring their child in for evaluation when something feels off, even if the temperature number seems “only” 101°F. Your sense that your child looks sicker than usual is real clinical information.
Common fever myths worth addressing:
Myth: “Fever above 104°F causes brain damage.” Fevers from infection essentially never reach the temperatures that cause direct brain damage (typically above 107°F sustained). Body temperature is biologically regulated even during infection. The danger comes from the underlying cause of the fever, not the heat itself. Heat stroke and other hyperthermia (not from infection) are a separate category and ARE dangerous.
Myth: “Fever needs to be treated to prevent seizures.” Febrile seizures happen in 2–5% of children, typically between 6 months and 5 years old. They are frightening but generally harmless. Fever-reducing medications have not been shown to prevent febrile seizures. (That said, a child who has had a febrile seizure should be evaluated to rule out other causes.)
Myth: “The exact number determines how sick they are.” Severity of illness correlates more with behavior, hydration, breathing, and other clinical signs than with the exact temperature.
How Long Is Too Long, Fever Duration Concerns
How many days the fever has been going on shifts the clinical picture significantly:
Days 1–2
Most fevers in children are caused by viral infections that resolve on their own. The first day or two of fever, in a child who otherwise looks okay, is usually managed at home with comfort measures and monitoring. Watch for the warning signs in this article.
Days 3–5
Many viral illnesses resolve in this window. Persistent fever beyond day 3 with no obvious source deserves evaluation by a doctor, either your pediatrician (during office hours) or an ER. Some bacterial infections (UTI, ear infection, sinus infection, pneumonia, strep throat) become more likely if a fever continues into this window.
Day 5+
Fever lasting more than 5 days in a child raises specific clinical concerns including Kawasaki disease, deep-seated abscess, atypical pneumonia, persistent UTI, mononucleosis, MIS-C (in children who recently had COVID-19), and rarely other rheumatologic or oncologic conditions. Any fever lasting more than 5 days deserves prompt medical evaluation, even if the child seems relatively okay.
Recurring or cyclical fever
Some children have recurrent fever syndromes that come and go in patterns. These need outpatient workup, not necessarily ER care, unless the child is acutely unwell during an episode.
Age-Specific Fever Rules
Under 3 months, Always come in
Any temperature of 100.4°F or higher (rectal) is an immediate ER evaluation. Young infants cannot fight infections the way older children can, and serious bacterial infections (UTI, blood infection, meningitis) can be present without obvious symptoms. The ER will do a full workup to identify the source. Do not wait.
3–6 months, Low threshold to come in
Fevers of 100.4°F or higher should be discussed with your pediatrician or evaluated at an ER, especially if the temp is 102°F or higher, or if any warning signs are present. UTIs are a common hidden cause of fever in this age group and require evaluation to identify.
6 months–2 years, Behavior matters most
By 6 months, the threshold shifts: now how the child looks and acts matters more than the exact number. A child who is alert, drinking, urinating, and making eye contact can often be managed at home with comfort measures and monitoring. A lethargic, dehydrated, or unusual-behaving child should be seen, regardless of the temperature.
Over 2 years, Watch behavior, hydration, and warning signs
Most fevers in this age group are viral and self-limited. Focus on warning signs (in the red-flag list above), hydration, breathing, and overall behavior. Fevers persisting beyond 3–5 days deserve medical evaluation. Sudden severe symptoms at any point are an ER visit.
Common Causes of Persistent Fever in Children
Most fevers in children come from one of these common causes:
- Viral upper respiratory infections, colds, flu, COVID, RSV. Fever typically lasts 2–5 days.
- Ear infections, often present with fever, ear pulling (in infants), pain, and fussiness.
- Strep throat, sore throat, fever, headache, sometimes abdominal pain in young children. Common in school-age kids.
- Urinary tract infections, in young children, often present primarily with fever without obvious urinary symptoms. Common hidden cause in infants and toddlers.
- Roseola, high fever for 3–5 days followed by a pink rash as the fever resolves. Common in infants and young toddlers.
- Hand, foot, and mouth disease, fever followed by sores on the hands, feet, and mouth.
- Croup, fever with a barking cough, often worse at night.
- Bronchiolitis, RSV and similar viruses in infants. See our Child Breathing Fast While Sleeping blog for details.
- Vaccination response, mild fever for 24–48 hours after some vaccines is common and not concerning unless other warning signs appear.
- Teething, may cause low-grade fever (under 100.4°F) but does not cause high fever. A child with a true fever should not be “blamed on teething.”
Serious Causes, What We Worry About with Persistent High Fever
When a fever is high, persistent, or paired with other warning signs, we consider these:
Pneumonia. Lung infection that can be bacterial or viral. Often presents with fever, cough, fast breathing, and sometimes chest pain. Severity ranges from mild outpatient illness to severe and requiring hospital admission.
Urinary tract infection / kidney infection. UTIs in young children, especially under 2, can present primarily with fever and few other symptoms. Kidney infections (pyelonephritis) cause high fever, flank pain, and can progress to sepsis if untreated.
Sepsis. The body’s extreme response to severe infection. Children with sepsis show fast heart rate, fast breathing, fever (or sometimes low body temperature), lethargy, decreased urination, and poor circulation. A medical emergency.
Meningitis. Infection of the lining around the brain and spinal cord. Symptoms include fever, severe headache, stiff neck, sensitivity to light, vomiting, lethargy, irritability, and in some cases a specific rash. Infants may show bulging fontanelle and high-pitched crying. A medical emergency.
Kawasaki disease. A rare inflammatory condition primarily affecting children under 5. The hallmark is fever lasting 5+ days that doesn’t respond well to fever-reducing medications, plus a combination of features: red eyes without discharge, red cracked lips and strawberry-red tongue, rash, swelling/redness of hands and feet (sometimes with peeling later), and swollen lymph nodes in the neck. Untreated, it can cause heart artery damage. Diagnosable and treatable when caught early.
MIS-C (Multisystem Inflammatory Syndrome in Children). A serious post-COVID inflammatory condition that can appear 2–6 weeks after a COVID-19 infection. Signs include persistent high fever plus features like rash, red eyes, abdominal pain, vomiting, diarrhea, swelling, and signs of inflammation in multiple organs. Needs urgent evaluation.
Appendicitis. Can present with fever, abdominal pain (often starting around the belly button and shifting to the lower right), nausea, vomiting, and loss of appetite. See our Sharp Stomach Pain blog for more.
Deep abscess or hidden infection. Persistent fever in a child who otherwise seems okay can occasionally be the only sign of a deep infection, in a tooth, sinus, bone, or other location. Worth investigating after several days of unexplained fever.
Travel-related infections. Children returning from international travel with persistent fever may have malaria, typhoid, dengue, or other travel-acquired infections. Tell the medical team about recent travel.
Mononucleosis (“mono”). Caused by Epstein-Barr virus, most common in adolescents. Causes persistent fever, severe sore throat, swollen lymph nodes, and significant fatigue. Usually self-limited but can last weeks.
Visible Warning Signs of Serious Illness
Beyond the temperature, these visible signs in a child with fever raise our concern significantly:
- Lethargy, not just sleepy, but unusually unresponsive or hard to engage
- Limpness or floppy body tone
- Trouble breathing, fast breathing, retractions, or grunting
- Pale, mottled, gray, or bluish skin
- Cool extremities despite fever (suggests poor circulation)
- Capillary refill longer than 2 seconds
- Severe headache, stiff neck, or sensitivity to light
- Bulging fontanelle in infants
- A non-blanching rash, small purple-red spots that don’t fade when pressed with a clear glass
- Persistent vomiting or refusing all fluids
- Dehydration signs (no wet diapers, no tears, dry mouth, sunken eyes)
- Inability to be consoled even by familiar caregivers
- Seizure
- A child who looks much sicker than the temperature would suggest
Special Populations, Lower the Threshold
Infants under 3 months
Always come in for any fever of 100.4°F or higher. This is a hard rule.
Children with chronic medical conditions
Sickle cell disease, congenital heart disease, immunodeficiency, kidney disease, neurologic conditions, and others all change the calculation. Fever in these children deserves earlier evaluation. Children with sickle cell disease and fever need to be seen urgently, they’re at high risk of serious infection.
Immunocompromised children
Cancer patients, transplant recipients, children on long-term steroids, those with primary immune deficiencies. Persistent fever in these children always needs evaluation. Their immune systems can’t fight off infections normally, and what looks routine can be severe.
Children with central lines or VP shunts
Indwelling medical devices increase the risk of bloodstream infection or device-related infection. Fever in these children deserves prompt evaluation.
Recent international travel
Children who’ve traveled internationally in the past month should mention this to the medical team. Some travel-related infections (malaria, typhoid, dengue) need specific testing.
Recent COVID-19 infection
Children who had COVID-19 within the past 6 weeks and develop new fever, especially with rash, red eyes, abdominal pain, or signs of multi-organ involvement, may have MIS-C. Get evaluated.
How an ER Evaluates Persistent High Fever in Children
At ER of Dallas, evaluation of a child with persistent fever is systematic, gentle, and focused on finding the source while making the child comfortable. Here’s what happens:
- Triage and vital signs, temperature, heart rate, breathing rate, blood pressure, oxygen saturation
- Full history, when the fever started, how it’s changed, response to fever reducers, other symptoms, sick contacts, medications, immunizations, recent travel, chronic conditions
- Comprehensive physical exam, ears, throat, lungs, heart, abdomen, skin, lymph nodes, neurological status
- Targeted testing based on what’s suspected, may include rapid strep test, urinalysis (catheterized in infants and young children unable to provide a clean sample), nasal swabs for flu/RSV/COVID, blood work (complete blood count, basic metabolic panel, inflammatory markers, blood cultures in severe cases)
- Chest X-ray when pneumonia is suspected
- Lumbar puncture (spinal tap) when meningitis is a concern, done gently with appropriate monitoring; an important test when needed
- IV fluids if the child is dehydrated
- Fever-reducing care and comfort measures during the visit
- Observation when the diagnosis is unclear and the child needs more time to evolve
- Pediatric hospital transfer coordinated directly when admission, surgery, or specialized care is needed (e.g., sepsis, meningitis, Kawasaki, severe pneumonia)
Most children come into our ER for persistent fever and go home the same visit with a clear diagnosis, next steps, and a follow-up plan. For cases requiring hospital admission, sepsis, severe pneumonia, meningitis, Kawasaki, MIS-C, we stabilize and coordinate transfer directly to a pediatric hospital.
When to Come to ER of Dallas vs. Monitor at Home
| Situation | What to Do |
| Child over 6 months with fever for under 3 days, alert and engaging, drinking fluids, normal urination, no warning signs, otherwise healthy child | Monitor at home. Comfort measures. Contact pediatrician for guidance on fever-reducing medications and follow-up. |
| Fever lasting beyond 3–5 days; OR fever in a 3–6 month old; OR any persistent fever in a child with a chronic medical condition; OR fever paired with mild-to-moderate symptoms that aren’t clearly diagnostic | Come to ER of Dallas for evaluation. Lab tests and exam can identify the cause and guide treatment. |
| ANY red flag from earlier in this article, infant under 3 months with any fever, lethargy, breathing trouble, severe headache, stiff neck, non-blanching rash, signs of sepsis, signs of meningitis, signs of dehydration, persistent fever 5+ days with rash/red eyes/swelling (possible Kawasaki), recent COVID with new multi-system symptoms (possible MIS-C) | 🚨 Call 911 (for severe distress) or come straight to ER of Dallas immediately. |
When in doubt with a child, come in. Children’s margins are smaller, and the cost of evaluation is far less than the cost of missing a serious cause.
What to Do While Monitoring at Home
If you’re managing fever at home and watching for warning signs, here’s safe general guidance:
- Focus on comfort, not the number. A child who feels okay at 101°F doesn’t need aggressive treatment. A child who feels miserable at 100°F may benefit from comfort measures.
- Offer fluids frequently. Water, oral rehydration solutions, breast milk, or formula, whatever your child usually drinks. Dehydration is a more immediate concern than the fever itself.
- Dress lightly. Don’t bundle a child in heavy blankets or layers, it traps heat. Light clothing helps the body release heat.
- Keep the room comfortable, not too warm, not too cold.
- Lukewarm sponge baths can help if the child is uncomfortable, but avoid cold baths or ice, they can cause shivering, which actually raises body temperature.
- For fever-reducing medications: follow specific guidance from your pediatrician for which medication, what dose, and how often. Do NOT give aspirin to children due to Reye syndrome risk. Do not combine or alternate medications without explicit pediatrician guidance.
- Do NOT give over-the-counter cough/cold medications to children under 6 without specific pediatrician guidance, these are not recommended for young children and can have serious side effects.
- Track the fever pattern, when it started, how high it gets, how it responds to medication, and any other symptoms. This is useful information for the ER team.
- Watch closely for any of the warning signs listed earlier in this article. If any appear, come in.
- Trust your instincts. If your child seems off, even if you can’t name why, come in.
Frequently Asked Questions
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Q: How high is too high for a child’s fever?
A: The temperature number alone isn’t the most important factor for most ages. For infants under 3 months, ANY temperature 100.4°F or higher is an immediate ER visit. For older children, how the child looks and acts matters more than the exact number, a lethargic child at 101°F can be more concerning than a playful child at 104°F. Fevers from infection essentially never reach the temperatures that cause direct brain damage.
Q: What does it mean if the fever won’t go down with medication?
A: Fever-reducing medications typically lower a child’s temperature by 2–3 degrees, not to normal. If the fever doesn’t drop at all after medication is given correctly, that can be a reason to be evaluated. It also may mean the medication wasn’t fully absorbed (if the child vomited it), the dose wasn’t correct for their weight, or the underlying infection is severe. Talk to your pediatrician about specific dosing for your child.
Q: How long should a fever last before I’m worried?
A: Most viral fevers resolve within 3–5 days. Fever persisting beyond 3 days deserves a doctor’s evaluation. Fever lasting 5+ days raises specific concerns including Kawasaki disease and warrants urgent evaluation regardless of how the child appears.
Q: My child had a seizure during a fever. What should I do?
A: Febrile seizures happen in 2–5% of children, usually between 6 months and 5 years. They’re frightening but generally don’t cause harm. After any first seizure, a child should be evaluated to make sure there’s no other cause. Call 911 if the seizure lasts longer than 5 minutes, the child has trouble breathing, or they don’t return to normal afterward.
Q: Is teething causing my baby’s high fever?
A: Teething can cause mild low-grade fevers (below 100.4°F) but does not cause true high fever. A baby with a true fever (100.4°F or higher) should not have it attributed to teething, there’s likely another cause. Infants under 3 months with any fever need ER evaluation.
Q: Should I take my child to the ER or to the pediatrician?
A: For non-urgent fever during business hours, your pediatrician is a great first call. For evening, overnight, or weekend symptoms; for any of the red flags in this article; or for persistent fever without a clear cause, come to the ER. We have on-site labs, imaging, and IV access that pediatrician offices don’t typically have.
Q: Will my insurance cover an ER visit?
A: Under the federal No Surprises Act, your insurance is required to process emergency visits at your in-network benefit level. ER of Dallas accepts most major insurance plans. We don’t accept Medicare, Medicaid, CHIP, or TRICARE.
Q: Do I need an appointment?
A: No. ER of Dallas is a 24/7 walk-in emergency room. Walk in or call +1 214-613-6694.
Q: Where is ER of Dallas located?
A: 4535 Frankford Rd, Dallas, TX 75287, Far North Dallas, easily reached from Carrollton, Addison, Plano, Frisco, and surrounding neighborhoods. Open 24/7.
Trust the Way Your Child Looks, We’re Open 24/7.
A fever that won’t come down sets off every parental alarm bell, and sometimes those alarms are right. The most important thing isn’t the number on the thermometer; it’s how your child looks, how they’re acting, how long the fever has been going, and how old they are. If anything about this fever feels different from what your child usually goes through, get them evaluated.
ER of Dallas is open 24/7 at 4535 Frankford Rd. We treat children every shift. Board-certified emergency physicians, on-site labs and imaging, child-friendly setting, and minimal wait. Walk in or call ahead.
🚨 Red-flag symptoms: Call 911 or come straight in.
📍 Address: 4535 Frankford Rd, Dallas, TX 75287
📞 Phone: +1 214-613-6694
🕐 Hours: Open 24/7, every day, every holiday
🌐 Website: https://erofdallastx.com/
