What Temperature Is Considered a Fever in Children? A Pediatrician Explains
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100.4°F (38°C) or higher is generally considered a fever.
Age matters. A baby younger than 3 months with a temperature of 100.4°F or higher needs prompt medical care.
For older children, also watch how your child looks and acts. Breathing and drinking are important too.
- 100.4°F (38°C) or higher is generally a fever.
- Normal body temperature can vary.
- The way you take a temperature matters.
- A higher fever does not always mean a worse illness.
- Watch how your child looks, drinks and breathes.
- Fever in a baby under 3 months needs prompt medical care.
What Is a Normal Temperature for a Child?
Many parents think 98.6°F is the one normal body temperature. It is not.
Normal temperature can vary. It may change during the day. Activity can change it too.
The way you take the temperature can also affect the reading. A number a little above 98.6°F does not always mean your child is sick.
What Temperature Is a Fever?
100.4°F (38°C) or higher is generally considered a fever.
A baby younger than 3 months with a temperature of 100.4°F (38°C) or higher needs prompt medical care.
A rectal temperature is the most accurate way to check for fever in a young infant. Do not wait for the number to go higher.
Does the Way I Take a Temperature Matter?
Yes. Different methods can give different readings.
A rectal temperature is most accurate for young infants. Forehead, ear and oral thermometers can be useful as children get older. Underarm readings are less exact.
Follow the directions for your thermometer. If a reading seems wrong, check it again.
Treat the child, not just the thermometer.
The number matters. But I also want to know how your child is doing. Are they drinking? Are they alert? Are they breathing comfortably?
Does a Higher Fever Mean a Worse Illness?
Not always. Common viral illnesses can cause high fevers. Some serious illnesses can cause lower ones.
This is why the number alone cannot tell us how sick a child is.
Watch your child, not just the thermometer. Look for:
- Drinking
- Wet diapers or urination
- Breathing
- Alertness
- Pain
- Vomiting or diarrhea
- A new rash
- Symptoms that are getting worse
Should I Treat Every Fever?
No. Fever medicine is mainly used to help a child feel better. The goal is not to make every reading 98.6°F.
An older child who is drinking and comfortable may not need medicine just because the thermometer shows a fever.
If you use fever medicine, dose it by your child's weight. Follow the label and your pediatrician's advice.
Dr. G's QuickDose™ gives weight-based dosing guidance for acetaminophen and ibuprofen.
QuickDose is an educational guide. It does not replace your child's pediatrician.
Call if:
- Your baby is under 3 months and has a temperature of 100.4°F or higher.
- The fever goes above 104°F more than once.
- Your child looks very sick or is getting worse.
- Your child is not drinking well.
- Your child has severe pain or repeated vomiting.
- Your child has a new or concerning rash.
- The fever lasts longer than expected or keeps returning.
- You are worried about your child.
Get emergency help if your child:
- Has serious trouble breathing
- Is very hard to wake or does not respond
- Has a seizure and does not recover normally
- Has a stiff neck and looks very sick
- Has a sudden purple or bruise-like rash
- Looks severely ill or gets worse quickly
Frequently Asked Questions
Is 99°F a fever?
Usually not. A temperature in the 99°F range can be normal.
Is 100°F a fever?
Usually not. It is below the common fever cutoff of 100.4°F (38°C).
Is 103°F dangerous?
Not by itself. Many common illnesses can cause a fever of 103°F. Watch how your child looks, drinks and breathes.
The Bottom Line
100.4°F (38°C) or higher is generally a fever. But age and symptoms matter too.
A baby under 3 months with a temperature of 100.4°F or higher needs prompt medical care. For older children, watch the child as well as the thermometer.
Related Fever Resources
Have another fever question? Visit our Fever in Children Parent Guide.
References
- American Academy of Pediatrics, HealthyChildren.org. Fever Without Fear: Information for Parents
- American Academy of Pediatrics, HealthyChildren.org. How to Take Your Child's Temperature
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