When a baby has a high fever that isn't accompanied by a runny nose, a cough, vomiting, or diarrhea, figuring out what's wrong can be difficult. There are many viral infections that can cause a fever and no other symptoms. Some viral infections, such as roseola, cause three days of very high fever followed by a light pink rash on the trunk. More serious infections, such as meningitis, urinary tract infections, or bacteremia (bacteria in the bloodstream), may also trigger a high fever without any other specific symptoms. If your baby has a high fever and no other symptoms, call the doctor.
When to seek medical advice
Fevers by themselves may not be a cause for alarm — or a reason to call a doctor. Yet there are some circumstances when you should seek medical advice for your baby, your child or yourself.
For infants
An unexplained fever is greater cause for concern in infants and children than in adults. Call your baby's doctor if your baby:
Is younger than 2 months of age and has a rectal temperature of 100.4 F or higher. Even if your baby doesn't have other signs or symptoms, call your doctor just to be safe.
Is older than 2 months of age and has a temperature of 102 F or higher.
Is a newborn who has a lower-than-normal temperature — under 95 F rectally.
Has a fever and unexplained irritability, such as marked crying when you change your baby's diapers or when he or she is moved. Some infants might have a fever and seem lethargic and unresponsive. In infants and children younger than age 2, these may be signs of meningitis — an infection and inflammation of the membranes and fluid surrounding your brain and spinal cord. If you're worried that your baby might have meningitis, see your doctor right away. Don't wait until morning to see your usual physician — meningitis is an emergency.