A fever in children is a temperature of 100.4°F (38°C) or higher. In most healthy kids over 3 months, fever isn’t dangerous on its own — it’s a sign the immune system is doing its job. What matters most is how your child looks and acts, not the exact number. Call your pediatrician right away for any fever in a baby under 3 months, a temperature above 104°F, a fever lasting more than 3 days, or if your child seems very ill, is hard to wake, or is breathing hard.
Few things send a parent reaching for the phone faster than a hot, flushed toddler at midnight. The good news: for most children, a fever is a normal, healthy response to a minor infection — and knowing what to look for turns a scary moment into a manageable one.
What counts as a fever?
A fever is a body temperature of 100.4°F (38°C) or higher. A child’s temperature naturally rises and falls through the day — it’s often lowest in the morning and highest in the late afternoon — so a reading of 99°F after running around the backyard usually isn’t cause for concern.
How you take the temperature matters, especially in babies:
- Under 3 months: a rectal temperature is the most accurate and the one we rely on for medical decisions.
- 3 months–4 years: rectal, or a forehead (temporal artery) thermometer for screening.
- 4 years and up: an oral thermometer works well once your child can hold it under the tongue.
Ear (tympanic) thermometers can be unreliable under 6 months. When in doubt with a young infant, a rectal reading is the standard your pediatrician will ask for.
Why fevers happen — and why they usually help
A fever isn’t the illness — it’s the body’s response to one. When the immune system detects a virus or bacteria, it raises the body’s set-point to make it a less comfortable place for germs to multiply and to help immune cells work faster. Most childhood fevers come from ordinary viral infections — colds, the flu, ear infections, and the everyday bugs kids swap at school and daycare.
Because fever is a symptom and not a diagnosis, the goal at home usually isn’t to force the number down to normal — it’s to keep your child comfortable and hydrated while their body does the work. A child who is drinking, resting, and still has moments of play is generally doing fine, even at 102°F.
When to call your pediatrician
The right response to a fever depends heavily on your child’s age. Younger babies have less-developed immune systems, so the threshold for calling is much lower.
Babies under 3 months
Call us — or seek care — for any rectal temperature of 100.4°F (38°C) or higher, even if your baby otherwise seems fine. Fevers in this age group are evaluated promptly, every time.
Ages 3 months to 3 years
Most fevers can be watched at home. Reach out if the fever climbs above 102°F for more than a day, lasts more than 3 days, or if your child seems unusually fussy, sluggish, or won’t take fluids.
Ages 3 and older
Focus on how your child is acting more than the number. A generally happy, drinking child can often be managed at home even with a higher fever.
- Is difficult to wake, unusually limp, or not responding normally
- Is breathing fast or working hard to breathe
- Has a stiff neck, a severe headache, or a rash that doesn’t fade when pressed
- Has a seizure, or has signs of dehydration (no wet diaper in 8 hours, no tears, dry mouth)
- Has a fever above 104°F that doesn’t come down with medication
Helping your child feel better at home
Comfort and fluids are the priorities. A few simple steps make a real difference:
- Offer fluids often — breast milk or formula for babies; water, diluted juice, or an electrolyte drink for older kids.
- Dress lightly and keep the room comfortable. Bundling in blankets can trap heat.
- Let them rest, but they don’t have to stay in bed if they’d rather be on the couch.
Acetaminophen (Tylenol) can be used from as young as your pediatrician advises; ibuprofen (Motrin/Advil) is for babies 6 months and older. Always dose by your child’s weight, not age, and never give aspirin to children. If you’re ever unsure of a dose, ask us before giving it.
Fever myths, cleared up
A lot of fever advice gets passed down that simply isn’t true:
- “Teething causes high fevers.” Teething may raise temperature slightly, but a true fever over 100.4°F points to a separate illness — don’t blame the teeth.
- “A high fever will damage the brain.” Fevers from infection top out around 105–106°F and don’t cause brain damage. Untreated overheating (like being left in a hot car) is a different danger entirely.
- “You must break the fever with medicine.” Medicine is for comfort, not for chasing a normal number. A comfortable, hydrated child at 102°F often needs nothing at all.
When you’re not sure, that’s exactly what your pediatrician is for. With direct-access membership, a quick text or call can save you a stressful late-night trip — and give you an answer from someone who knows your child.
