A febrile infant includes any child under the age of 2 months old who has a fever of 100.4 degrees Fahrenheit or higher. Fevers can be caused by bacterial or viral infections. Because infants do not have fully developed immune systems, they are more likely to get infections that adult immune systems would fight off. While fevers are most often caused by common illnesses such as colds, infants may have a more serious infection that requires medical attention. The younger an infant is, the higher the risk for serious infection. For example, a baby under 3 weeks of age is treated slightly differently than a baby older than 4 weeks of age.
Fever is an important cause for concern in infants. A baby who has a serious infection could also be lethargic, irritable or inconsolable. The baby may cough, vomit or have diarrhea. He or she may not want to eat and may sleep more than usual. Newborns typically sleep an average of 16 hours per day.
You can check your baby's temperature at home by using a medical thermometer. Doctors at Riley at IU Health recommend using a digital rectal thermometer for the most accurate results. Seek medical attention if your child's temperature is 100.4 degrees Fahrenheit or higher. If your baby’s temperature is taken through the armpit, ear or forehead, the results may be less accurate. Parents who take their child's temperature this way may want to see their child's pediatrician if the fever is near 100.4 degrees Fahrenheit.
You should not give your baby acetaminophen or any other medicine to reduce the fever before going to the doctor. These medicines can hide symptoms, leading to an incorrect diagnosis.
Not all fevers in infants are caused by serious illnesses. However, doctors cannot know the cause of the fever without proper testing. Doctors at Riley at IU Health practice the best guidelines for diagnosing and treating febrile infants. Each infant with a fever is checked for sepsis through a rule out sepsis work-up. The sepsis work-up includes tests such as:
It is routine for infants younger than 6 weeks old with a fever of 100.4 degrees Fahrenheit or higher to be admitted to the hospital while diagnostic tests are processed. The management for 6-week-old children to 2-month-old children is somewhat more flexible and based on factors such as how sick the baby appears and what is most likely causing the fever.
Depending on their exact age, most infants will also begin receiving antibiotics before test results are available. Because infections can cause serious long-term problems, treatment should not be delayed. Once results from the rule out sepsis work-up are complete, your child’s treatment will be tailored to fit the cause of the fever. He or she may receive specific antibiotics or an antiviral agent to fight the infection.
Your child will also receive supportive care, including:
If your baby is doing well and all tests are negative for serious infections after 48 hours, he or she will be able to go home.
To learn more about fevers in infants, please visit the resources below:
Riley at IU Health offers a broad range of supportive services to make life better for families who choose us for their children's care.
This website from the American Academy of Pediatrics includes information about fevers in babies as well as many other topics.
The Hospitalist Department at Riley at IU Health is currently participating in a pilot research project to speed up the diagnosis of serious infections. The goal of this research is to ensure the accuracy of a new blood test that may be able to reveal the cause of infections in just two hours instead of 48 hours.
If your infant comes to Riley at IU Health with a fever, you may be asked if you would like to participate in this pilot project. While your baby will still receive a rule out sepsis work-up that takes 48 hours to complete, he or she will also have the new blood test completed. If the blood test is successful, you and your child will have helped future families get answers and care faster than ever before.
