Pediatric Fever of Unknown Origin

These conditions can cause a fever:

• Infectious diseases
• Certain medicines
• Heat stroke
• Blood transfusion
• Disorders in the brain
• Some kinds of cancer
• Some autoimmune diseases

Fever is not an illness. It is a symptom, or sign, that your body is fighting an illness or infection. Fever stimulates the body's defenses, sending white blood cells and other "fighter" cells to fight and destroy the cause of the infection.

Children with fevers may become more uncomfortable as the temperature rises. Along with a body temperature greater than 100.4°F (38°C), symptoms may include:

• Your child may not be as active or talkative as usual.
• Your child may seem fussier, less hungry and thirstier.
• Your child may feel warm or hot. Remember that even if your child feels like he or she is "burning up," the measured temperature may not be that high.

The symptoms of a fever may look like other health conditions. According to the American Academy of Pediatrics, if your child is younger than 3 months of age and has a temperature of 100.4°F (38°C) or higher, you should call your child's healthcare provider right away. If you are unsure, always check with your child's healthcare provider for a diagnosis.

In children, a fever that is making them uncomfortable should be treated. Treating your child's fever will not help the body get rid of the infection any faster. It simply will relieve discomfort linked to the fever. Children between the ages of 6 months and 5 years can develop seizures from fever (called febrile seizures). If your child does have a febrile seizure, there is a chance that the seizure may occur again. But usually children outgrow the febrile seizures. A febrile seizure does not mean your child has epilepsy. There is no evidence that treating the fever will reduce the risk of having a febrile seizure.

Give your child an antifever medicine, such as acetaminophen or ibuprofen. DON'T give your child aspirin. It has been linked to a serious, potentially fatal disease, called Reye syndrome.

Other ways to reduce a fever:

• Dress your child lightly. Excess clothing will trap body heat and cause the temperature to rise.
• Encourage your child to drink plenty of fluids, such as water, juices or popsicles.
• Give your child a lukewarm bath. Do not allow your child to shiver from cold water. It can raise the body temperature. Never leave your child unattended in the bathtub.
• Don't use alcohol baths.

Unless advised otherwise by your child’s healthcare provider, call the provider right away if:

• Your child is 3 months old or younger and has a fever of 100.4°F (38°C) or higher. Get medical care right away. Fever in a young baby can be a sign of a dangerous infection.
• Your child is of any age and has repeated fevers above 104°F (40°C).
• Your child is younger than 2 years of age and has a fever of 100.4°F (38°C) that lasts for more than 1 day.
• Your child is age 2 or older and has a fever of 100.4°F (38°C) that lasts for more than 3 days.
• Your baby is fussy or cries and can't be soothed.