Stephen J. Schueler, M.D.

Overview Evaluation taking temperatures Treatment Home Care medications warning signs Underlying Cause Types

Fever Newborn Evaluation

An evaluation of a fever in an infant begins with a medical history and physical examination.

Options for measuring the temperature include:

  • Rectal temperature:
    • Very reliable
    • Best option for infants
  • Oral thermometer:
    • Unreliable results in infants
  • Under the arm temperatures:
    • Unreliable results
  • Thermometer ear probe:
    • In some cases can provide unreliable results
  • Thermometer skin patches:
    • Unreliable results

Test may be required in the following infants:
  • An infant less than 2 months old, who has a fever over 100.4 degrees F (38 C)
  • An infant less than 2 years old, who has a fever over 101.9 degrees F (38.8 C)

Tests that may be used to evaluate an infant less than 3 months old, who has a fever over 100.4 degrees F (38 C) include:

Tests that may be used to evaluate an infant less than 2 years old, who has a fever over 101.9 degrees F (38.3 C) include:

Additional tests may be performed, based on the presence of additional symptoms.

Fever Newborn Taking Temperatures

The temperature should not be measured for at least 20-30 minutes after eating or drinking. You should also wait at least 30 minutes to check the temperature after the infant has had a bath.

Rectal temperatures are the most accurate, and should be the only method used to check temperatures in a newborn or infant. A well lubricated rectal thermometer should be inserted gently into the rectum no more than 1/2 to 1 inch. It should be left for 1 minute, after which time it can be read. Digital thermometers can obtain a reliable reading in a few seconds.

Mothers should not be concerned: rectal temperatures are very safe and are not harmful. Do not use oral thermometers to measure a rectal temperature. Rectal temperatures tend to run about 1 degree F. above oral temperatures. A rectal temperature above 100.4 degrees F. (38 C) represent a fever.

Continue to Fever Newborn Treatment

Last Updated: Dec 13, 2010 References
Authors: Stephen J. Schueler, MD; John H. Beckett, MD; D. Scott Gettings, MD
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PubMed Fever Newborn References
  1. Losek JD. Acetaminophen dose accuracy and pediatric emergency care. Pediatr Emerg Care. 2004 May;20(5):285-8. [15123898]
  2. McCarthy P. Fever without apparent source on clinical examination. Curr Opin Pediatr. 2005 Feb;17(1):93-110. [15659971]
  3. Miller LC, Sisson BA, Tucker LB, Schaller JG. Prolonged fevers of unknown origin in children: patterns of presentation and outcome. J Pediatr. 1996 Sep;129(3):419-23. [8804332]
  4. Perrone J, Hollander JE, Datner EM. Emergency Department evaluation of patients with fever and chemotherapy-induced neutropenia. J Emerg Med. 2004 Aug;27(2):115-9. [15261351]
  5. Russell FM, Shann F, Curtis N, Mulholland K. Evidence on the use of paracetamol in febrile children. Bull World Health Organ. 2003;81(5):367-72. [12856055]
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