Fever in Kids: What Counts as a Fever, When to Call the Doctor and How to Keep Your Child Comfortable

Quick answer: a fever is generally a temperature of 100.4°F (38°C) or higher. Call the doctor immediately for any fever in a baby younger than 3 months. For older children, the American Academy of Pediatrics says to call right away if the child looks very ill, is unusually drowsy, has a stiff neck, trouble breathing, an unexplained rash or repeated vomiting, has had a seizure, has a weakened immune system, or if the temperature rises above 104°F (40°C) repeatedly. Also call if a fever lasts more than 24 hours in a child under 2, or more than 3 days in a child 2 or older. Offer fluids, dress your child lightly and ask your doctor or pharmacist about the right medicine dose.

Few things make a parent’s heart jump like a hot forehead in the middle of the night. A fever feels like an emergency, yet in most cases it is a sign that your child’s body is doing exactly what it should, fighting off an infection.

The trick is knowing when a fever is routine and when it needs a call to the doctor. This guide gathers advice from the American Academy of Pediatrics and other health agencies into plain steps you can use at 2 a.m. It is part of our family health and safety guide, and it pairs with our checklist on when to keep your child home from school. This article is general information, not medical advice, and your child’s doctor knows your child best.

Sources: American Academy of Pediatrics HealthyChildren.org pages “Fever Without Fear,” “Fever and Your Baby,” “Fever: When to Call the Pediatrician” and “How to Take Your Child’s Temperature”; HealthyChildren.org guidance on febrile seizures and on medicines for fever; U.S. Food and Drug Administration consumer information on children’s acetaminophen and ibuprofen; Centers for Disease Control and Prevention information on Reye syndrome and aspirin. Checked November 2026. This article is not a substitute for medical care. If you are worried about your child, call your pediatrician or local emergency number.

What Counts as a Fever

A normal body temperature varies with age, activity and time of day. According to the American Academy of Pediatrics, a fever is usually a temperature of 100.4°F (38°C) or higher. That number applies to a rectal reading and is generally used as the cutoff for oral, ear and forehead readings as well. Underarm readings can run lower, so a reading under the arm may need a lower cutoff.

Fever by itself is not an illness. It is a sign that the body is fighting something, most often a virus. The AAP describes fevers as generally harmless and sometimes a good sign that the immune system is working. What matters more than the number is how your child looks and acts, and how old your child is.

Take a Real Temperature

Feeling a forehead is not accurate, especially when a child has chills, and temperature strips are not reliable either, according to the AAP. Use a digital thermometer.

Which thermometer for which age

• Babies and young children: a rectal reading is the most accurate, especially for babies under 3 months. Ask your pediatrician to show you how, and use a thermometer reserved for that purpose.
• Ear thermometers: the AAP advises avoiding them for babies younger than 6 months because their ear canals are too small for an accurate reading.
• Forehead (temporal artery) and oral thermometers: these can be used for older children who can hold a thermometer under the tongue or sit still. Follow the manufacturer’s directions.
• Underarm readings: these are easy but less accurate and may be used as a screening step. Confirm a high reading with a better method if you are worried.

Keep a digital thermometer where you can find it in a hurry, and write down the temperature, the time and any medicine you gave. That log is helpful if you call your doctor.

When to Call Right Away

The AAP’s guidance lists situations that call for contacting the doctor right away. Use these as a quick checklist.

By age

• Under 3 months (12 weeks): a rectal temperature of 100.4°F (38°C) or higher needs a call to the doctor immediately, even if your baby seems fine. A doctor needs to check for serious infection.
• 3 to 6 months: the AAP says to let the doctor know if a fever reaches 101°F (38.3°C) or higher.
• Over 6 months: the AAP says a temperature of 103°F (39.4°C) or higher is a reason to notify the doctor.
• Any age: call if the temperature repeatedly rises above 104°F (40°C).

By symptoms

Call the doctor right away if your child has a fever and:

• Looks very ill, is unusually drowsy or is very fussy.
• Has been in a very hot place, such as an overheated car.
• Has a stiff neck, severe headache, severe sore throat, severe ear pain, trouble breathing, an unexplained rash, or repeated vomiting or diarrhea.
• Shows signs of dehydration such as a dry mouth, crying without tears, a sunken soft spot or noticeably fewer wet diapers.
• Has a weakened immune system, for example from cancer or sickle cell disease, or takes steroids or similar medicines.
• Has a heart problem that may make a fever harder to tolerate.
• Has had a seizure.

By how long

Also call the doctor if:

• Your child still acts sick after the fever comes down.
• Your child seems to be getting worse.
• The fever lasts more than 24 hours in a child younger than 2.
• The fever lasts more than 3 days (72 hours) in a child 2 or older.

If you are ever unsure, calling is the right choice. Pediatric offices and many nurse advice lines expect these calls and will tell you whether to watch at home, come in or go to the emergency department.

When to Call 911

Call your local emergency number if your child has trouble breathing, is hard to wake or unresponsive, has blue or gray lips or skin, has a seizure lasting more than five minutes, or shows signs of a severe allergic reaction. Do not wait for a callback if your child’s condition seems life-threatening.

Keeping Your Child Comfortable at Home

For a child who is older than 3 months and otherwise acting reasonably well, the goal is comfort, not a particular number. The AAP highlights these steps:

1. Offer plenty of fluids. Fever makes the body lose fluid faster. Water, breast milk, formula, oral rehydration solutions and popsicles can help. Watch for signs of dehydration.
2. Dress lightly. A single layer is fine. Use a blanket if your child has chills, and remove it when they are warm.
3. Let them rest as much as they want, and do not force food.
4. Keep the room comfortable, not hot and not freezing.
5. Watch behavior. A child who plays, drinks and interacts after a dose of fever medicine is usually a reassuring sign, according to the AAP.

What not to do

• Do not use alcohol baths or ice packs. The AAP says these practices are no longer recommended and can cause harm.
• Do not bundle a feverish child in heavy blankets, which can raise body temperature.
• Do not give aspirin. Aspirin has been linked to Reye syndrome, a rare but serious illness, in children and teens recovering from viral infections, according to the CDC.
• Do not leave a child alone in a hot car or room, and never assume a high temperature is only from the weather.

Fever Medicine: What to Know

Medicine is optional. Not every fever needs treatment, and the main reason to give it is to help a child feel more comfortable. If you do use it:

• Acetaminophen and ibuprofen are the two common choices. Follow the label, use the measuring device that comes with the product and never guess a dose by eye.
• For children under 2, the AAP says to contact your pediatrician or pharmacist for the correct dose.
• Babies under 12 weeks should not receive fever medicine unless a doctor says so, because they need to be examined first.
• Ibuprofen is not recommended for babies under 6 months, according to the AAP and the FDA labeling.
• Do not combine products that contain the same active ingredient, such as a cold medicine with acetaminophen plus a separate acetaminophen dose.
• Keep medicine locked up and out of reach. Our guide to poison prevention at home covers safe storage.

Write down the time and dose each time so that nobody doubles up.

Febrile Seizures

A small share of young children, typically between about 6 months and 5 years, can have a seizure when their temperature rises quickly. These febrile seizures are scary to watch. The AAP says that most are brief and do not cause lasting harm, but any first seizure should be evaluated by a doctor.

If it happens:

• Stay calm and lay your child on their side on a safe surface.
• Do not put anything in the mouth.
• Do not hold your child down.
• Note how long it lasts.
• Call your local emergency number if it lasts more than five minutes, if your child has trouble breathing afterward or if you cannot wake them.
• Call your doctor after any seizure, even a short one.

Fever and Common Childhood Illnesses

Most fevers come from viral infections such as colds, flu and stomach bugs. Others come from ear infections, strep throat, urinary tract infections or other bacterial illnesses that may need treatment. A doctor may look for the cause when a fever is high, lasts several days or comes with specific symptoms such as ear pain, a sore throat or burning with urination.

Vaccines protect against several infections that can cause fever, including influenza. Follow the schedule your pediatrician recommends, and ask about seasonal vaccines before winter.

Fever After Vaccines

Mild fever, fussiness and soreness for a day or so can follow vaccination. If your baby is under 3 months, any fever of 100.4°F or higher needs a call to the doctor. For older children, use the same guidelines above, and let your doctor know if the fever lasts longer than expected or your child seems unusually ill.

Going Back to School or Daycare

Many schools and daycares ask that children stay home until they have been fever-free for 24 hours without the help of fever-reducing medicine. The CDC uses that standard in its guidance for flu, and local policies often follow it. A fever that comes back after medicine wears off means the illness is still active, so resting at home is the safest choice for your child and for classmates.

Check your school’s handbook, since rules differ for stomach illness, pink eye and other conditions. If your child has a long-lasting fever, keep a record of temperatures and symptoms to share with the doctor. Our checklist on when to keep your child home from school covers common illnesses and typical return rules.

Rest matters, too. Sick children often sleep more than usual, and that is helpful. Our guide on how much sleep kids need lists typical ranges by age so you can tell when changes in sleep are normal and when they are a reason to check in with a doctor.

A Simple Home Plan

• Keep a digital thermometer, a measuring syringe and the pediatrician’s phone number in one place.
• Know your child’s weight, since doctors may ask for it when they advise on medicine.
• Write down temperatures, times, symptoms and doses.
• Keep sick-day basics on hand, such as oral rehydration solution and plain foods.
• Decide in advance who stays home with a sick child and how you will handle the school or daycare rules.
• Use the call-right-away list above as a checklist, and call when you are unsure.

Frequently Asked Questions

Frequently Asked Questions

What temperature is a fever in a child?

The AAP says a fever is usually 100.4°F (38°C) or higher. The reading method matters, and underarm readings may run lower.

How high is too high?

Height of the fever matters less than the child’s age and behavior. Call right away for any fever in a baby under 3 months and when the temperature repeatedly rises above 104°F (40°C) at any age.

How long can a fever last before I call the doctor?

Call if it lasts more than 24 hours in a child under 2, or more than 3 days in a child 2 or older.

Should I wake my child to give fever medicine?

Usually not. Rest is helpful, and medicine is meant for comfort. Ask your pediatrician if you are unsure.

Can teething cause a high fever?

A high fever should not be blamed on teething without a doctor’s input. Call your doctor if you have a baby with a fever, especially under 3 months.

The Bottom Line

A childhood fever is most often a sign that the immune system is working. The number on the thermometer matters less than your child’s age, behavior and other symptoms. Call right away for any fever under 3 months, for temperatures that repeatedly pass 104°F, for fevers that last longer than the AAP limits and for any warning signs. Offer fluids, keep your child comfortable, avoid aspirin and unsafe cooling methods and trust your instincts to call your pediatrician when something feels wrong.