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Key Points

  • Regardless of age, all toxic-appearing infants and children with fever require a full septic work-up, urgent treatment with broad-spectrum antibiotics, and admission.

  • Initial management of fever in infants less than 30 days old includes a complete examination of cerebrospinal fluid, blood, and urine for a serious bacterial infection, prompt empiric antibiotic administration, and hospitalization.

  • Management of well-appearing febrile infants aged 1–3 months is determined by analyzing risk factors for serious bacterial infection.

  • Well-appearing, low-risk, febrile infants and children who do not have a source of infection must have reliable follow-up when discharged from the emergency department.


Fever in children is defined as a rectal temperature ≥38.0°C (100.4°F) and accounts for approximately 20% of all pediatric visits to the emergency department (ED). Fever is part of a larger, comprehensive host response to infection. Leukocytes and other phagocytic cells release pyrogens, which trigger an increase in prostaglandin synthesis, resulting in an elevation of the thermoregulatory set point. Fever occurs when the hypothalamus responds to this new set point by initiating physiologic changes involving endocrine, metabolic, autonomic, and behavioral processes. Specific physiologic changes associated with fever such as increased oxygen consumption, protein breakdown, and gluconeogenesis can quickly deplete the already limited reserves of infants and children.

Fever can be the first and only physiologic sign of illness. It can herald a serious bacterial infection (SBI) such as meningitis, bacteremia, osteomyelitis, septic arthritis, urinary tract infection (UTI), or pneumonia. These and other SBIs can rapidly lead to sepsis, an overwhelming and devastating systemic syndrome caused by infection. A child or infant with a SBI may appear “toxic” (very ill-appearing with unstable vital signs). Alternatively, well-appearing febrile children can also have an SBI such as occult bacteremia. Occult bacteremia is the presence of pathogenic bacteria in the blood of well-appearing, febrile children without any identifiable focus of infection, also described as “fever without a source.” Approximately 20% of all children presenting with fever will have no identifiable cause. Neonates (<30 days old) have immature immune systems that place them at high risk for SBI with fever.

Clinical Presentation


Elicit the duration, pattern, and maximum recorded temperature from caregivers. Young infants do not usually have localizing symptoms and often present with nonspecific complaints such as excessive crying, poor feeding, irritability, or lethargy. Parents of older children may report more specific complaints such as cough, rhinorrhea, sore throat, vomiting, diarrhea, dysuria, joint pain, body aches, or headache. Questions regarding oral intake and urine output will help the clinician assess the degree of associated dehydration, if present.

The presence of a seizure in a febrile infant may suggest a benign simple febrile seizure or could be an indicator of meningitis. A simple febrile seizure is defined as a single generalized tonic-clonic seizure that lasts <15 minutes in children aged ...

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