Recognize and respond to fever in infants

Fever in infants is defined as a rectal temperature of 100.4°F (38°C) or higher. It is the body's natural immune response to infection, not an illness itself. Use a digital rectal thermometer for the most accurate reading in babies under 3 months -- axillary and forehead thermometers are less reliable at this age.

Key Age-Based Guidelines

• Under 3 months: Any fever of 100.4°F or higher requires immediate medical evaluation. Do not give fever-reducing medication -- go to the pediatrician or emergency room right away
• 3-6 months: Contact the pediatrician for fevers of 102°F (38.9°C) or higher, or if the baby appears unusually irritable or lethargic
• Over 6 months: Acetaminophen (Tylenol) can be used per pediatrician-directed dosing based on weight; ibuprofen (Advil/Motrin) can be introduced after 6 months of age

Tips

• Never give aspirin to infants or children due to the risk of Reye's syndrome
• Dress the baby in lightweight clothing -- overbundling can raise body temperature further
• Offer frequent feeds to prevent dehydration
• Focus on how the baby is acting, not just the number on the thermometer -- a baby with 101°F who is alert and feeding well is less concerning than a baby with 100.5°F who is limp and unresponsive
• Always dose fever medication by weight, not age, and confirm dosing with your pediatrician