If the baby will not allow you to properly take their fever under their tongue, simply take the thermometer and get an underarm temperature. If the temperature is over 99-100, you should consider using a rectal thermometer.
If your baby is younger than 3 months old, contact the doctor for any fever. If your baby is 3 to 6 months old and has a temperature up to 102 F (38.9 C) and seems sick or has a temperature higher than 102 F (38.9 C), contact the doctor.
