102.5 Fever in an Infant

A fever is an increase in the baseline body temperature. Fevers are part of the body's response to infection or inflammation, helping the immune system in its fight against offending microbes and indicating when there is an ongoing inflammatory process. The definition of fever in children is a rectal temperature of 100.4 degrees Fahrenheit or higher. Rectal thermometers give you the most accurate measurement of body temperature in children.


Infants are a special patient population when it comes to fevers. According to the Merck Manuals, infants have a poorly developed or immature immune system, which can predispose them to serious bacterial infections. Also, because of their age, it is sometimes difficult to pinpoint the actual source of the fever. Infants are unable to pinpoint if they have ear or throat pain, and they exhibit general or nonspecific symptoms both during mild and serious illnesses, such as:

  • fever
  • decreased oral intake
  • irritability
  • lethargy


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An infant with a temperature of 102.5 needs evaluation by a health provider in order to determine the source of the fever. According to the American Academy of Family Physicians, younger infants--those under two months of age--are at particular risk for serious bacterial infections, such as:

  • bacteremia
  • which is the presence of bacteria in the bloodstream; urinary tract infection;
  • meningitis
  • which is an infection of the meninges
  • the tissue that surrounds the brain

In older infants (up to a year of age), the risk for these infections decreases somewhat.


The American Academy of Family Physicians recommends that infants with a fever of 102.5 who do not have an obvious source for fever need evaluation for the presence of serious bacterial infections. Infants less then two months of age may need evaluation of their blood, urine and spinal fluid. Spinal fluid is the fluid that surrounds the brain and the spinal cord, which can be infected if the child has meningitis. During this evaluation, infants stay in the hospital receiving intravenous antibiotics until a bacterial infection is ruled out. Older infants who do not appear ill can have the evaluation as outpatients, with close follow-up by a health provider. If the child appears ill, then hospitalization and a thorough evaluation may be warranted.


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Despite the concerns for serious bacterial infections, most fevers are benign and do not require treatment. If the infant with a fever of 102.5 is irritable or dehydrated, she may benefit from a fever-reducing medicine. The Merck Manuals recommend using acetaminophen and/or ibuprofen as appropriate over-the-counter remedies for fevers in infants. Aspirin is not a safe alternative in children, as it can interact with certain viruses to cause Reye syndrome, a life-threatening condition that can cause swelling of the brain and liver damage. Ibuprofen is not recommended for infants younger than six months of age.


Infants between six months and one year of age with a fever of 102.5 can have a febrile seizure. According to the National Institute of Neurological Disorders and Stroke, febrile seizures usually occur when a child's temperature is higher than 102 degrees F, especially during the first day of an illness. These seizures are generally harmless and have no long-term consequences.