A normal body temperature for children is around 98.6°F (37°C), but it naturally fluctuates throughout the day and varies depending on where you take the reading. A child officially has a fever at 100.4°F (38°C) or higher when measured rectally, in the ear, or on the forehead. Understanding what’s normal, how to measure accurately, and when a fever actually needs attention can save you a lot of unnecessary worry.
Normal Temperature Ranges by Method
There’s no single “normal” number for kids. The reading depends on where you place the thermometer. Rectal temperatures run highest, armpit temperatures run lowest, and oral falls in between. Here are the normal ranges for each method:
- Rectal: 97.9°F to 100.4°F (36.6°C to 38°C)
- Ear (tympanic): 96.4°F to 100.4°F (35.8°C to 38°C)
- Oral: 95.9°F to 99.5°F (35.5°C to 37.5°C)
- Armpit (axillary): 94.5°F to 99.1°F (34.7°C to 37.3°C)
A child’s temperature also shifts naturally by about 1°F over the course of a day, typically lowest in the early morning and highest in the late afternoon. Activity, clothing, and even a hot bath can nudge the number up temporarily without meaning anything is wrong.
What Counts as a Fever
The threshold for fever depends on the measurement method. Your child has a fever if you see:
- Rectal, ear, or forehead: 100.4°F (38°C) or higher
- Oral: 100°F (37.8°C) or higher
- Armpit: 99°F (37.2°C) or higher
Armpit readings are the least accurate of all methods, so if an armpit reading looks borderline, it’s worth rechecking with a more reliable method. A reading just above the line doesn’t necessarily mean your child is sick. Many mild viral infections produce low-grade fevers that resolve on their own.
Best Thermometer for Each Age
The most accurate method changes as your child grows, mostly because younger children can’t cooperate with an oral reading.
For babies from birth to about 2 years old, a rectal temperature with a standard digital thermometer is the gold standard. You can use an armpit reading as a quick screen, but if it’s elevated, follow up rectally. Recent research suggests forehead (temporal artery) thermometers can also provide accurate readings in newborns, though rectal remains the reference.
For children between 2 and 5, rectal is still the most reliable option. Ear thermometers and forehead scanners are reasonable alternatives, but earwax or a small, curved ear canal can throw off the reading. One study of children under 3 found that armpit thermometers detected only about 12% of fevers that a rectal thermometer caught, while forehead scanners caught about 62%. That gap matters when you need a precise number.
By age 4 or 5, most kids can hold a digital thermometer under their tongue long enough for an oral reading. Ear and forehead thermometers also work well at this age. Pacifier thermometers and fever strips are not considered reliable enough to use.
Treat the Child, Not the Number
One of the biggest shifts in pediatric thinking over the past decade is this: the goal of treating a fever is comfort, not hitting a specific number on the thermometer. How your child looks and acts matters far more than whether the reading is 101°F or 103°F. A child who is alert, drinking fluids, and still interested in playing is generally doing fine, even with a fever that sounds high.
Fever itself is part of the immune response. It helps the body fight infection. Scientific evidence does not support the idea that bringing the number down speeds recovery. The real benefit of fever-reducing medicine is that it helps your child feel well enough to rest, eat, and stay hydrated.
When your child is clearly uncomfortable, irritable, or not sleeping well because of the fever, that’s when medication makes sense. Acetaminophen can be used at any age (with your pediatrician’s guidance for dosing in very young infants). Ibuprofen is an option starting at 6 months old and can be given every 6 to 8 hours as needed. Always dose by your child’s weight rather than age for the most accurate amount.
Physical cooling measures like sponge baths or fans are no longer recommended. They’re unpleasant for the child and don’t address the underlying reason for the fever. Their only real use is in cases of heat-related illness, which is different from an infection-driven fever.
When a Fever Needs Immediate Attention
Age is the single biggest factor in how seriously to take a fever. The younger the baby, the more urgent the situation.
For any infant under 2 months old with a rectal temperature of 100.4°F or higher, go to the emergency department right away. At this age, a fever can signal a serious bacterial infection, and doctors will want to run tests quickly. The American Academy of Pediatrics has detailed clinical guidelines specifically for evaluating febrile infants between 8 and 60 days old, reflecting how carefully this age group needs to be assessed.
For babies 3 to 6 months old, contact your pediatrician if the temperature reaches 102°F (38.9°C) or higher. For children older than 6 months, the general threshold for calling your doctor is 103°F or higher.
Regardless of the number on the thermometer, seek emergency care if your child shows any of these signs alongside a fever: extreme drowsiness or difficulty waking up, a stiff neck, signs of dehydration (no tears when crying, very little urination, dry mouth, or sunken eyes), or simply looking very ill in a way that concerns you.
Can a High Fever Cause Brain Damage?
This is one of the most common fears parents have, and the answer is reassuring. Only extremely high fevers, above 107.6°F (42°C), pose any risk to the brain. A fever driven by a typical infection essentially never reaches that level. Temperatures that high are associated with environmental heat emergencies, not with colds or flu.
Febrile seizures are another major source of worry. About 4% of children will experience a seizure triggered by a fever at some point. These episodes are frightening to watch but almost always stop on their own within five minutes. They do not cause brain damage, do not lead to developmental delays or learning disabilities, and do not mean your child has epilepsy. The seizures tend to happen as the temperature is rising rapidly, which is why they often occur before a parent even realizes the child has a fever.
Practical Tips for Taking a Temperature
If your child feels warm and you want an accurate reading, a few small things help. Wait at least 15 minutes after eating or drinking before taking an oral temperature, since hot or cold foods skew the result. For rectal readings in infants, lubricate the tip of the thermometer and insert it only about half an inch. Hold your child still and keep a hand on the thermometer the entire time.
With ear thermometers, gently pull the ear back and up to straighten the ear canal before inserting the probe. For forehead scanners, follow the manufacturer’s instructions on how to swipe across the skin, and avoid taking a reading right after your child has been wearing a hat or lying with their forehead against a pillow.
Whatever method you use, take two readings a minute apart if the first one surprises you. Write down the number and the time so you can track whether the fever is rising, stable, or coming down. That information is exactly what your pediatrician will want if you end up calling.