Fever is not an illness. It is the body’s response to one, and the number on the thermometer tells you far less about how serious things are than most people expect.
Arlington ER works out what is causing the fever, with imaging and labs on site around the clock. Any fever in a baby under three months old is an emergency, whatever else seems fine.
In adults, a fever above 103 degrees deserves attention, and anything above 105 needs urgent care. But the number is the least useful part of the picture, and how the person looks and behaves matters far more.
An adult at 104 who is alert and drinking is usually in less danger than one at 101 who is confused. The signs below are what actually decide the visit.
The rash test is worth knowing by heart. Press the side of a clear glass firmly against the rash. If the spots stay visible through the glass rather than fading, that can indicate a serious bloodstream infection and needs an ambulance, not a car journey.
Because a baby under three months cannot yet contain an infection, and because they show almost no outward signs until they are already very unwell. A temperature of 100.4 degrees or above in that age group is an emergency regardless of how settled they seem.
Their immune system is not yet able to wall off an infection in one place. What would stay a urine infection or a chest infection in an older child can spread into the bloodstream and to the lining of the brain within hours.
The second problem is that newborns do not look sick in the way older children do. There is no dramatic decline to watch for. A baby with a serious bloodstream infection may simply feed a little less and sleep a little more, right up until they are critically unwell.
This is why the rule is absolute rather than a judgment call, and why it applies even at three in the morning, even on a holiday, and even when the baby has just been checked. Nobody will think you overreacted.
Between three and six months the threshold is only slightly less strict. Above six months there is more room for judgment, and how the child looks and behaves starts to matter more than the reading.
Because how high a fever goes says very little about what is causing it. A mild virus can push a child to 104. A life-threatening bloodstream infection can sit at 100.5, or produce no fever at all.
Fever is a defense, not the disease. Raising body temperature makes life harder for bacteria and viruses and helps the immune system work, which is why bringing a fever down does not treat the underlying infection. It makes the person more comfortable, and comfort is a perfectly good reason, but the illness runs its own course either way.
What genuinely matters is how the person looks and behaves. A child who is drinking, making eye contact, and playing between temperature spikes is usually fine. A child who is limp, will not make eye contact, or cannot be roused properly needs attention no matter what the thermometer reads.
The opposite mistake is more dangerous and less discussed. Older adults, people on treatment that suppresses the immune system, and newborns can all have a serious infection with a low fever or none at all. In those groups, the absence of a high temperature is not reassurance.
There is one exception where the number does matter on its own. Above roughly 106 degrees, the temperature itself becomes harmful rather than merely uncomfortable, and that needs cooling urgently.
Comfort and fluids do most of the work. The right-hand column contains two old remedies that are still widely used and actively make things worse.
| Do this | Never do this |
|---|---|
| Offer fluids constantly, in small amounts | Wait for them to ask before offering a drink |
| Dress in one light layer | Bundle up in blankets to sweat it out |
| Use lukewarm water if bathing | Use a cold bath, ice, or rubbing alcohol on the skin |
| Give fever-reducing treatment for comfort | Give it to a child under twelve weeks without advice |
| Watch behavior rather than the thermometer | Recheck the temperature every ten minutes |
| Note when the fever started and how high it has gone | Assume a normal reading means the illness has passed |
The third row deserves emphasis because both of those remedies are still passed down through families. A cold bath or ice makes the body shiver, and shivering generates heat, so the core temperature often rises rather than falls. Rubbing alcohol is worse still: it absorbs through the skin, and children have been poisoned by it.
Bundling in blankets comes from the same instinct and has the same problem. Someone with a fever feels cold because their body has raised its target temperature, but wrapping them up traps the heat they need to shed.
Find the source. A fever is a signal, and the entire visit is about locating what is producing it rather than simply lowering the temperature and sending you home.
Throat, ears, chest, abdomen, skin and urine. Fever always comes from somewhere, and the examination is systematic.
Strep, flu, urine and blood tests chosen by what the examination found, not ordered as a routine bundle.
Chest X-ray for a cough or fast breathing, CT or ultrasound when the abdomen is the likely source.
Fever burns through fluid quickly. IV fluids when drinking is not keeping up, plus treatment to bring comfort.
Babies under three months get a complete evaluation for serious infection, because outward signs cannot be relied on.
What is causing it, how long it should last, and written signs that mean coming straight back.
A febrile seizure is a convulsion triggered by a rising temperature in a young child. They affect roughly one child in twenty-five, they are terrifying to watch, and the great majority cause no lasting harm at all.
They typically happen between six months and five years, usually early in an illness as the temperature climbs rather than at its peak. That is why they so often arrive with no warning, before anyone realized the child was becoming unwell.
If one happens, put the child on their side on the floor away from furniture, do not put anything in their mouth, and note the time it started. Most stop within two or three minutes on their own.
Call 911 if the seizure lasts more than five minutes, if it repeats, if breathing is difficult afterward, or if the child does not return to themselves within an hour. Otherwise the child still needs to be seen the same day, because the seizure is a signal to find out what infection caused it.
The reassurance worth hearing is that a simple febrile seizure does not cause brain damage and does not mean the child has epilepsy. Around a third of children who have one will have another during a later illness. Bringing the fever down faster does not prevent them, which is worth knowing so no parent feels they failed to act quickly enough.
A baby under three months with a fever is triaged straight through, at any hour, without exception.
Lowering a temperature is easy. Finding what is producing it is the part that changes the outcome.
The three most common hidden sources of fever, all testable here without a second appointment.
Bringing in a feverish child who turns out to have a virus is the right call, not a wasted trip.
A fever visit is billed as an emergency visit plus whatever testing is needed to find the source. What varies most is how hidden the source turns out to be.
Fever is the symptom that most often makes parents feel judged about cost, so it is worth being plain. A well-looking child over six months with a fever, drinking and playing between spikes, can usually wait for their own pediatrician in the morning. That is cheaper and perfectly safe, and we would rather tell you than take the visit.
What should never be weighed against cost is a fever in a baby under three months, a fever with confusion or a stiff neck, or a rash that does not fade under a glass. Those are the situations where hesitating is the expensive decision.
The cost pattern here is unusual in one respect. A fever with an obvious source is a short, inexpensive visit. A fever with no obvious source needs more testing to exclude the hidden causes, so two patients with identical temperatures can leave with very different bills. Your physician will explain why each test is being added as it happens.
The federal No Surprises Act protects patients from surprise bills for emergency care. Our Financial Support and Care Relief Program can substantially reduce out-of-pocket costs for those who qualify, and our Billing Disclosure page sets out the detail.
For billing questions: 817-973-7406 or info@arlingtoner.com
Arlington ER serves Arlington, Texas from 1607 S. Bowen Rd., on the west side of Bowen just south of Pioneer Parkway. Parking is directly outside the entrance, a few steps from the door with a sick child in your arms.
We are minutes from central Arlington and the Parks Mall, and a short drive from Dalworthington Gardens, Kennedale, Grand Prairie, and Mansfield. From I-20, exit at Bowen Road and head north. From Highway 303 or Pioneer Parkway, turn south onto Bowen and we are on your right. Our Contact Us page has anything else you need.
Call 911 rather than driving if there is a seizure, a rash that does not fade under a glass, difficulty breathing, or a child who cannot be woken properly. For everything else, walk in at any hour with no appointment needed.
Bring them in at any hour, even if they seem settled. Newborns hide serious infection until they are already very unwell, and nobody here will think you overreacted. Open 24/7, no appointment needed.
A temperature of 100.4 degrees or above. Below that is not a fever, whatever someone feels like to the touch. Judging temperature by hand is unreliable in both directions, which is why a reading matters when a decision hangs on it.
Good enough for most situations, and convenient. For a baby under three months, where the decision is absolute, a rectal reading is the accurate one. Tell us which method you used, because it changes how we read the number.
No. Sleep is doing more good than the reading would. What matters is whether they can be roused normally when you do need to wake them, and whether they drink when offered.
More than three days deserves assessment even if everything else seems settled. Most viral fevers break within seventy-two hours, so one that keeps going suggests something else is driving it.
Body temperature naturally rises in the late afternoon and evening, and the hormones that suppress inflammation are at their lowest overnight. It is a normal pattern, not a sign the illness is worsening after dark.
No. Teething may raise the temperature very slightly but does not cause a genuine fever. Blaming teething for a temperature above 100.4 is one of the most common ways a real infection gets missed in babies.
Worth being seen. A fever that returns after a clear improvement can mean a second infection has settled on top of the first, such as a chest or ear infection following a virus. It is a recognized pattern rather than bad luck.
Yes, and it is the reason we never rely on the number alone. Newborns, older adults, and anyone whose immune system is suppressed can be seriously infected with a normal or even low temperature.
Medically reviewed by the Arlington ER Clinical Team | Last Reviewed: August 2026