Any fever in a baby under 3 months is an emergency.
What to say on the phone
When calling 911 or the ER
“My baby is [AGE] weeks old and has a fever of [TEMPERATURE] taken rectally. We are on our way to the emergency room.”
Newborns have immature immune systems and cannot fight infections like older children. A fever may be the only sign of a serious bacterial infection like meningitis, urinary tract infection, or bloodstream infection. These conditions can progress rapidly in young infants.
Temperature 100.4°F (38°C) or higher rectally
Lethargy or difficult to wake
Refusing to feed or poor feeding
Bulging soft spot (fontanelle) on head
Mottled or pale skin
High-pitched or weak cry
Fewer than 4 wet diapers in 24 hours
This guide is for quick reference and does not replace professional medical advice. When in doubt, call your pediatrician or go to the ER.