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What is a fever?

A fever is a body temperature higher than 100.4° F (38° C). It is a symptom, not a disease. Fever can help the body fight an infection. Often it is caused by a viral infection (such as a cold or stomach bug), but sometimes it can be caused by a bacterial infection. If a fever comes and goes for a long time, your doctor may look for other, rarer causes that aren’t an infection. Sometimes the fever ends on its own, with no cause found at all. 

How do I check for a fever? 

Children can feel warm and not have a fever. For example, if your child is very active or sleeping in warm clothing/blankets they may feel warm. Babies may also have a slightly higher temperature when teething, although not usually higher than 100° F. Using a digital thermometer to measure their temperature is the best way to determine if they have a fever. 

Your child’s temperature can be measured under the arm, on the forehead, in the mouth, or in the rectum, and it varies slightly in each place. Please use the method as recommended by your child's healthcare provider. For infants less than 3 months old, a rectal temperature is best. If you call your clinic about your child's fever, say which method you used. 

High fevers don't necessarily mean that your child is very sick or that they will need antibiotics. High fevers generally do not cause any harm to your child. High body temperatures caused by heat from outside of the body (such as being left in a hot car or spending too long outside in very hot weather) are dangerous, however. 

How should I care for my child?

Keep your child comfortable. Lightweight clothes will help your child cool down. If your child gets cold, use a light blanket. 

Give extra fluids to prevent dehydration (getting "dried out"). 

Sponging and bathing are not recommended, as they may cause shivering. Shivering actually increases the temperature. Do not sponge with rubbing alcohol, as it may be absorbed through the skin, causing bad side effects. 

Fever does not always need to be treated. The main reason to give medicine for a fever is to help your child feel better. If your doctor or nurse practitioner advises a fever-reducing medicine, ask which one to use. Do not give aspirin or aspirin-containing products to children or teens. 

Take your child's temperature before you give any more fever medicine. This will help you know if the temperature is rising and avoid giving medicine that is not needed. 

Sometimes kids with a fever breathe faster than usual and may have a faster heart rate, too. 

When should I call the clinic?

Call if your child:

  • Is younger than 3 months and has a temperature of 100.4° F or higher or a temperature below 97°F. Babies’ immune systems are not fully developed, and this can be a sign of a serious bacterial infection. 
  • has a fever that lasts for more than 48 hours and is older than 3 months 
  • has a fever that won't come down with medicine, or a fever that keeps rising 
  • is crying constantly, or is very fussy and cannot be comforted 
  • is listless or has little energy 
  • is sleeping more and is hard to wake up 
  • has neck pain or stiffness or a severe headache 
  • refuses to drink 
  • has less urine than usual 
  • has vomiting or diarrhea 
  • has a fever that went away for a few days and now is back 
  • is still breathing fast after their fever comes down 

Call 911 if your child:

  • has trouble breathing 
  • has purple spots on their skin or bruising that wasn’t there before 
  • has a seizure 
  • is leaning forward and drooling 


This sheet is not specific to your child, but provides general information. If you have any questions, please call your clinic.

Reviewed 2/2024

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This page is not specific to your child, but provides general information on the topic above. If you have any questions, please call your clinic. For more reading material about this and other health topics, please call or visit Children's Minnesota Family Resource Center library, or visit

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