What to Do When Your Baby Has a Fever

A high fever can be harmful for a newborn, but taking effective steps will greatly reduce this risk. Learn how to treat baby fevers and when to visit the doctor.

As any parent knows, your baby's first fever can be downright frightening. It turns out that "fever phobia" is justifiable: temperatures greater than 100.4 degrees Fahrenheit can lead to life-threatening infections (such as bacterial meningitis and pneumonia) in newborns less than 3 months old.

But don't panic! With the proper steps, it's unlikely that a newborn's fever will lead to complications. And luckily, there are many effective steps you can take to reduce their fever and greatly lowering their risk of adverse outcomes. Here's what to do when your baby has a fever—plus guidance from the American Academy of Pediatrics on how to handle infant fevers.

What Causes a Baby's Fever?

There are variety of reasons why your baby may have a fever. "The most common cause of fever is infections from viruses or bacteria," such as colds, flu, ear infections, and strep throat, says Anne Tran, M.D., a pediatric hospitalist at Kaiser Permanente in Hawaii. Believe it or not, developing a fever is actually beneficial in these cases since it proves that your baby's immune system is working properly to fight off the infection.

Dr. Tran says that certain immunizations can also cause a temporary fever for as long as 48 hours, which is a normal response to vaccinations. In rare cases, fevers can point to brain disorders or autoimmune disorders.

What is Considered a Fever for a Baby?

A normal temperature is 98.6 degrees Fahrenheit (37 degrees Celsius) plus or minus one degree (.6 degrees Celsius). Note that "normal" body temperature varies slightly from person to person and also may change throughout the day. However, 99.6 and above is considered high or having a fever, and according to the AAP, a "true fever" is 100.4 degrees Fahrenheit.

What's the Best Way to Check a Baby's Temperature?

Just by putting your hand on your baby's forehead, you'll most likely be able to tell right away if they have a fever. However, if they do feel overly warm, you'll want to take their temperature so that you'll know how high it is. There are multiple types of thermometers to choose from, but their accuracy varies.

Experts recommend using a rectal thermometer for anyone less than three years old age. These give a more accurate reading than oral thermometers since you actually insert the bulb into the body (1/2 to 1 inch into your child's rectum). Any reading above 100.4 degrees Fahrenheit is considered a fever and cause for concern in babies, says Lana Gagin, MD, MPH, FAAP, at Spectrum Health Helen DeVos Children's Hospital.

Signs of Fever in Babies

Besides having an elevated temperature, other signs of fever in babies include:

  • Excessive sleepiness
  • Fussiness
  • Lack of appetite
  • Redness of the skin and/or sweating

It's also important to make sure the baby isn't actually suffering from heat stroke, which is elevated body temperature caused by overheating. Prevent heat stroke by avoiding sun exposure or overdressing or over-bundling your baby, especially if your baby is less than 6 months old. "If you suspect your child is overheated, immediately move him to a cool place," says Dr. Gagin. "Call your pediatrician or take your child to the emergency room."

Baby Fever

How to Treat Your Baby's Fever

See medical help right away if your baby has a "true fever." "In newborns under three months, any temperature over 100.4 degrees is considered a medical emergency," says Dr. Tran. Babies under three months don't have fully functioning immune systems, which increases the risk of infections like bacterial meningitis and pneumonia. It's important they get evaluated right away to prevent life-threatening complications.

If your baby is between 3 months and 6 months old, call the doctor for a fever over 101 degrees F. You should also alert the pediatrician if your baby develops vomiting, diarrhea, ear pain, stiff neck, skin rash, inconsolable crying, shortness of breath, or other worrisome symptoms— or if they have trouble moving or walking. Also watch out for signs of dehydration in your baby, which include lack of tears and less than three or four wet diapers a day, says Dr. Tran.

Consider relieving the discomfort of a lower-grade fever with acetaminophen (for babies over 3 months) or ibuprofen (for babies over 6 months). Keep in mind, however, that these medications temporarily mask a fever, but they won't treat symptoms. Call your doctor to discuss the proper dosage.

Don't overdress your feverish baby or cover them in thick blankets, "as this can prevent body heat from escaping and cause their temperature to rise," says Dr. Tran. Consider giving them a lukewarm bath or dribbling a lukewarm washcloth over their body. Finally, let your child rest and keep them well hydrated. "And spend some extra time together. A hug from a loving relative goes a long way," says Dr. Gagin.

AAP Guidance on Treating Infant Fevers

So what happens if you bring your newborn to the doctor for a fever? As it turns out, there was previously no protocol for dealing with fevers in young babies; treatment could range from short observation to extensive testing at the hospital (such as a lumbar puncture). This prompted the American Academy of Pediatrics (AAP) to release standardized guidelines— published in July 2021 in Pediatrics—to set protocols for dealing with elevated temperatures in infants between 8 to 60 days old.

The new AAP guidelines are broken down by age: 8-21 days, 22-28 days, and 29-60 days. They help doctors determine whether babies with a fever (100.4 degrees Fahrenheit or more) who appear otherwise healthy should be admitted to the hospital.

"What is good about these guidelines from the perspective of a parent is they are based on all the science accumulated over the decades on how to manage an infant with a fever," Dr. Sean O'Leary, a co-author of the guidelines, vice-chair of the Committee on Infectious Diseases for the American Academy of Pediatrics, and a professor of pediatrics at the University of Colorado, Anschutz Medical Campus, told Today.

Parents should alert their pediatrician right away if their baby has a fever, especially if the baby is younger than 60 days old. Hopefully, these guidelines will eliminate unnecessary medical costs and streamline treatments in the future.

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