A fever is usually a symptom of an illness or an infection. It could also mean that the body is fighting an illness and the immune system is working. If your baby has a fever, this could mean that they have caught a cold or other viral infection. Other conditions such as pneumonia, urinary tract infections, ear infections, or a more serious infection such as a blood bacterial infection or meningitis may be causing the fever.
Babies can also have fever in reaction to a vaccination or if they become overheated from being dressed too warmly or spending too much time outside on a hot day.
To know for sure that your baby has a fever, you should always use a digital thermometer to check your child’s temperature either via the rectum (rectally), mouth (orally), ear, under the arm (axillary), or at the temples. The American Academy of Pediatrics (AAP) recommends only using digital thermometers in children. Never use a mercury thermometer because they pose a risk of mercury exposure and poisoning if they break.
For infants and toddlers, be sure to use a rectal thermometer correctly. A rectal thermometer may accidentally poke a hole in (perforate) the rectum. It may also pass on germs from the stool. Always follow the product maker’s directions for proper use. If you don’t feel comfortable taking a rectal temperature, use another method.
Here are guidelines for fever temperature:
- Ear temperatures aren’t accurate before 6 months of age.
- Don’t take an oral temperature until your child is at least 4 years old.
- Ask your child’s healthcare provider how you should take the temperature of your infant under 3 months old.
Temperature Measurements:
- Rectal or forehead (temporal artery) temperature of 100.4°F (38°C) or higher, or as directed by the provider.
- Armpit temperature of 99°F (37.2°C) or higher, or as directed by the provider.
Signs of Fever in Newborns
When newborns have a fever, they may act differently, and they may also be crankier and fussier than usual. They may also sleep poorly, refusing to eat, lack interest in play, be less active or even lethargic and they may have convulsions or seizures.
If your baby is under one month and has symptoms of a fever, contact your child's doctor immediately or take the baby to the Pediatric Emergency Center nearest to your home.
