by Dr. Bridget O’Brien

  • Fevers in the majority of us are actually a good thing. Fever is our body’s way of doing what it is supposed to do when it is exposed to a foreign pathogen. Pathogens are those pesky viruses, bacteria and fungi that invade the body and cause infection (and we help protect against with immunizations). They can be transmitted by saliva, stool, respiratory droplets in the air (i.e. expelled when someone coughs), or infected skin in certain diseases.  Fever means the body is revving up its defenses to help fight that intruder. So when your child develops a runny nose, cough, vomiting, diarrhea and then develops a fever, his/her body is doing what it is supposed to be doing!
  • So when should parents worry? Read on!

Newborns and fever:

  • From birth to when your baby is 12 weeks old, you should call your Pediatrician with any fevers of 100.4 Fahrenheit or higher.
  • Per the current guidelines, any fever of 100.4F or higher in a baby 0 to 8 weeks old needs to be seen in the emergency department. We strongly recommend Children’s Hospital of Wisconsin’s ER. There is a specific work-up that needs to ensue, and you can talk to your pediatrician in more detail about what that is.
  • Any baby from 0 to 4 weeks old with a fever of 100.4 or higher will also need that work-up in the emergency department (CHW ER), and will need to spend the night in the hospital.

Newborns can hide serious infections and not show any signs until it’s too late which is why these guidelines are in place. It is very important that you always call your pediatrician with any concerns for fever in this age group.

What classifies as fever?

  • Body temperature normally fluctuates throughout the day, peaking in late afternoon and evening. 98.6 F is average temperature, but this can fluctuate up to the 99s normally and not classify as a fever. Low-grade fever is 100 to 101F. True fevers (in infants older than 12 weeks) are 101.5F or higher. Fevers 100-104F are actually good for your child as they help fight off infection.

How long is too long to have a fever?

  • *Most* viral illnesses (like the common cold, “stomach flu”) are accompanied by fevers up to 3-4 days. Fevers lasting longer than this should prompt a visit to your pediatrician to ensure it’s not a bacterial infection or other fever-causing illness.

When to treat a fever?

  • My rule of thumb is to treat any fever if your child seems to be affected by it (fussy, listless, uncomfortable), or if the temperature is 103F or higher. *Most* kids can tolerate lower fevers just fine and it’s always best to avoid medication if you can. If you do not treat the fever it does not mean the fever will keep going higher. The brain has a built-in thermostat to counter this phenomenon.  Remember: that fever is for a reason and it’s ok to have one.
  • Your body’s fluid needs increase in the setting of fever, so it is important to encourage extra fluids when your child is having fevers.

How to treat a fever?

  • Remember to call your pediatrician if your 8-12 week old child has a fever before giving medication.
  • Infants and children 2 months and older can receive Tylenol. Tylenol can be dosed every 4-6 hours as needed. However, they should get no more than 5 doses in 24 hours. Tylenol is dosed based on weight. We have a reference chart on the resources page of our website.
  • Infants and children 6 months and older can also receive ibuprofen. Ibuprofen can be dosed every 6-8 hours as needed. Ibuprofen is dosed based on weight. We have a reference chart on the resources page of our website.
  • If your child is having high-spiking fevers and seems to be very affected by them, you can alternate Tylenol and ibuprofen every 3 hours for 2-3 days until the fevers resolve. (Give Tylenol, then 3 hours later ibuprofen, then 3 hours later Tylenol again, etc.) What you’ll be doing is giving Tylenol every 6 hours and ibuprofen every 6 hours individually. Make a chart to keep track of when you give each medicine. If you’re uncertain about alternating medicines, it is OK to stick to using just one fever reducing medicine at a time as directed above.
  • Cool washcloths across the forehead and stripping off excess clothing can also be helpful if fever medicine alone is not working.
  • You can trial a lukewarm bath if the other options above are not working right away for high-spiking fevers. If your child starts to chill, make the water temp warmer.
  • Do not give Tylenol and ibuprofen at the same time.
  • Do not use rubbing alcohol.

How high is too high a fever?

  • It takes a temperature of 108F or higher to have any deleterious effect on the brain. Fevers this high typically occur when the air temp is high, like in heat stroke, and are very unlikely to occur from common illnesses.
  • If your child spikes a fever over 104F but it starts to come down (may not completely resolve, but should trend down 1-3 degrees) within 30-60 minutes of Tylenol or ibuprofen, that’s a good sign. If it still doesn’t break with fever reducing medicines, you should call your pediatrician for further guidance. It doesn’t necessarily mean something bad, it’s more so how your child looks at the time, but it’s always helpful to talk this out with your pediatrician over the phone.
  • I also recommend calling your pediatrician if fevers are 105F or higher.
  • We cannot diagnose viral vs bacterial infections based on height of fever alone.

When do I just go to the clinic or ER?

  • There are certain conditions that fall outside the advice above. If your child has any of the following, he/she will need to be seen:
  • very ill appearance and fever
  • limp and fever
  • eye swelling and fever
  • cellulitis and fever
  • boils and fever
  • limb pain/swelling and fever
  • back pain and fever
  • neck pain/stiffness and fever
  • inconsolability and fever
  • neck swelling and fever
  • inability to swallow liquid or saliva and fever
  • retractions (breathing in so hard ribs are showing) or nasal flaring and fever
  • hard, fast breathing that doesn’t improve when you treat the fever

The list above is by no means exhaustive, and if your parental gut-instinct is alarming and you are concerned with how your child looks or is behaving, it is always best to err on the side of caution and call or see your Pediatrician. Fevers in children can be scary and we as Pediatricians recognize that. It is important to keep in mind that our bodies are smart and fevers occur for a reason. More often than not, it’s ok for your child to have one; they’re helping your child fight off infection! Follow the above advice and utilize your Pediatrician with any other questions or concerns.

(The exceptions to the advice below are children with chronic illness such as sickle cell disease, inflammatory bowel disease, cancer, organ transplants, immunodeficiencies, metabolic syndromes, CF, abnormal kidneys, VP shunts, etc.).

Information from AAP Healthychildren contributed to parts of this post.