Fever itself is not an illness. It is a sign that the body is fighting an illness or infection. Fever sparks the body’s defenses, sending white blood cells and other “fighter” cells to combat and destroy the infection. 

While most fevers are not a sign of serious illness, it can be hard to quickly identify the cause of a baby’s fever while avoiding unnecessary tests or hospital stays. More than 10% of infants with fever are diagnosed with a urinary tract infection. The chance of your baby having a more serious bacterial infection is much lower.

Technically, a temperature of 100.4° F (38° C) or higher taken rectally (in the bottom) is considered a fever. The following is a good guide to follow during your baby’s first year of life:

Newborns age 28 days or younger

If your baby is 28 days or younger with a rectal temperature of 100.4° F, seek emergency care immediately.

28 days - 6 months old

If your baby is 28 days to 6 months old with a rectal temperature of 100.4° F, he/she should be seen by your provider or an urgent care facility very soon. Call your provider for instructions.

6 months and older

Typically, infants 6 months and older can be treated with fever reducers such as Tylenol® or Motrin® at the direction of your provider.