When you bring a child with a high fever to the emergency room, the medical team will work quickly to assess how sick your child is, bring the fever down, find the cause, and make sure there’s no serious infection. The specific steps depend heavily on your child’s age. A newborn with a 100.4°F fever gets a very different workup than a 5-year-old with a 103°F fever.
Here’s what to expect at each stage, from the moment you walk in to when you go home.
The First Assessment: Triage
The triage nurse will take your child’s temperature, heart rate, and breathing rate and ask you how long the fever has lasted, how high it’s been, and whether your child has been drinking fluids. They’ll also look at your child’s overall appearance: alertness, skin color, and responsiveness. A child who is limp, difficult to wake, or has mottled skin will be moved to a treatment room faster than a child who is fussy but alert and making eye contact.
The ER team is trained to screen for signs of sepsis, a dangerous response to infection. They look at blood pressure (adjusted for age), level of consciousness, and how well your child is breathing. If any of these are significantly off, the team shifts into a higher-urgency protocol immediately.
How Age Changes Everything
Age is the single biggest factor in how aggressively the ER investigates a fever. The younger the child, the more testing is required, because young infants can have serious bacterial infections with very few outward signs.
Newborns Under 21 Days
Any fever at or above 100.4°F (38°C) in a baby this young is treated as a medical emergency. The team will draw blood cultures, collect a urine sample, test for herpes simplex virus, and perform a lumbar puncture (spinal tap) to check for meningitis. This sounds frightening, but it’s standard practice because newborns have immature immune systems and can deteriorate rapidly. Nearly all babies in this age group are admitted to the hospital and started on antibiotics while results come back.
Infants 22 to 60 Days
The workup is similar but slightly more flexible. Blood and urine cultures are still drawn, and the team checks inflammatory markers, with procalcitonin being the most accurate single marker for identifying serious bacterial infection. If those markers come back normal and the urine looks clean, your baby may be spared a spinal tap. If any marker is elevated (procalcitonin above 0.5 ng/mL or a high neutrophil count), a lumbar puncture is typically performed. Many of these babies are still admitted for observation, though some with completely normal results and a reliable follow-up plan can go home.
Older Infants and Children
Once a child is past 2 or 3 months, the ER approach becomes more targeted. The team looks for an obvious source of infection: an ear infection, a throat infection, a urinary tract infection. If your child looks well, is drinking fluids, and has a clear source for the fever, blood work may not be necessary at all. Testing is reserved for children who look particularly unwell, have very high fevers (especially above 104°F), have no obvious infection source, or have underlying health conditions.
Bringing the Fever Down
The ER uses the same two medications available at home: acetaminophen (Tylenol) and ibuprofen (Advil, Motrin). Acetaminophen is dosed by weight at about 15 mg per kilogram and can be used in babies as young as 2 months. Ibuprofen is available for children 6 months and older, dosed at about 10 mg per kilogram, and tends to last a bit longer (6 to 8 hours versus 4 to 6).
If your child is vomiting and can’t keep medicine down, the ER can give acetaminophen rectally, which works just as well. Contrary to what many parents expect, the ER doesn’t typically use IV medications to treat fever itself. The fever reducers are given by mouth or rectally, just like at home, but the ER has the advantage of dosing precisely by weight rather than by the age ranges on the box.
For fevers below 102°F, medicine isn’t always necessary. Fever itself is part of the body’s immune response and isn’t inherently dangerous. The goal of treatment is comfort, not hitting a specific number on the thermometer.
Physical Cooling
You may see the staff remove extra blankets or clothing to help your child cool down. Tepid sponge baths (water around 85°F to 90°F) are sometimes used if a child is very uncomfortable, but they’re considered a comfort measure, not a primary treatment. Cold baths and ice packs are avoided because they can cause shivering, which actually raises the body’s core temperature. Rubbing alcohol should never be applied to a child’s skin; children can absorb enough through the skin to cause poisoning.
IV Fluids and Hydration
Fever increases fluid loss, and many feverish children don’t want to eat or drink. The ER will first encourage oral fluids, small sips of water, breast milk, formula, or an electrolyte solution. IV fluids are started when a child can’t keep liquids down, shows signs of moderate to severe dehydration (less than half the usual wet diapers, no tears when crying, dry mouth), or looks “toxic,” meaning unusually lethargic or ill-appearing. The IV also gives the team quick access if antibiotics or other medications are needed.
If Your Child Has a Febrile Seizure
About 2 to 5 percent of children between 6 months and 5 years will have a seizure triggered by a rapid rise in temperature. These are terrifying to witness but are usually harmless. If the seizure lasts less than 5 minutes and involves the whole body symmetrically (a “simple” febrile seizure), the ER provides supportive care: positioning the child safely, monitoring breathing, and waiting for the seizure to stop on its own. No anti-seizure medication is needed.
If a seizure lasts 5 minutes or longer, the team will give medication to stop it, typically through the nose or rectally if there’s no IV in place. Once the seizure ends, the priority shifts to finding the cause of the fever. A spinal tap to check for meningitis is considered if the child is very young, not fully immunized, or shows signs of a brain infection like a stiff neck or prolonged confusion. For a straightforward first febrile seizure in an otherwise healthy child, brain imaging and EEGs are not routinely ordered.
What the Team Is Really Looking For
The fever itself isn’t what concerns the ER. They’re trying to answer one question: is this a routine viral illness, or is there a bacterial infection that needs antibiotics? Most childhood fevers are caused by viruses and will resolve on their own. The dangerous minority includes urinary tract infections, bacterial pneumonia, bloodstream infections, and meningitis.
The team uses a combination of your child’s appearance, age, fever height, and lab markers to sort this out. Each degree Celsius above 101.3°F (38.5°C) roughly doubles the risk of serious bacterial infection in young infants. That’s why higher fevers in younger babies prompt more aggressive testing. Viral testing (nasal swabs for flu, RSV, and similar viruses) can help too: if a clear viral culprit is identified, the likelihood of a simultaneous bacterial infection drops, though it doesn’t eliminate it entirely.
Going Home vs. Being Admitted
The ER will send your child home if they meet a few key criteria: they’re drinking well enough to stay hydrated, their vital signs are stable, initial lab work (if done) looks reassuring, and you have a plan for follow-up with your pediatrician. You’ll be given specific instructions about when to return, which typically include a fever lasting more than 3 to 5 days, new symptoms like a rash or difficulty breathing, refusal to drink, or your child becoming significantly harder to wake or less responsive.
Admission is more likely for newborns and very young infants regardless of how well they look, for children who are dehydrated and not improving with oral fluids, for any child with abnormal inflammatory markers while culture results are still pending, and for children who simply look too sick to safely go home. Cultures take 24 to 48 hours to grow, so some babies are kept in the hospital on precautionary antibiotics until those results come back negative.
What You Can Do While You’re There
Bring a list of any medications your child has already taken at home, including the dose and timing. This prevents accidental double-dosing of acetaminophen or ibuprofen. Know your child’s recent weight if possible, since all medication doses are calculated by weight. Keep your child in light clothing, and offer small sips of fluid frequently. The ER visit for a fever can take anywhere from 2 to 6 hours depending on whether labs are drawn and how quickly results return, so having a comfort item and staying calm will help both of you get through the wait.