Fever classification

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]


Pyrexia (fever) can be classed as:

  • Low grade: 38–39°C (100.4–102.2°F)
  • Moderate: 39–40°C (102.2–104.0°F)
  • High-grade: 40–42°C (104.0–107.6°F)
  • Hyperpyrexia: Over 42°C (107.6°F)

Febricula is a mild fever of short duration, of indefinite origin, and without any distinctive pathology.[1]

Fever patterns

  • Sustained fever: the fluctuation in temperature during a 24-hour period is 0.3 °C (0.5 °F) or less.
  • Remittent fever: the temperature is elevated, and it falls each day, but not to normal, remaining 37.3 °C (99.2 °F) or above. The excursion in temperature is more than 0.3 °C (0.5 °F) and less than 1.4 °C (2.5 °F).
  • Intermittent fever: the temperature is elevated but falls to normal (37.2 °C [99 °F] or below) each day. The excursion in temperature is more than 0.3 °C (0.5 °F) and less than 1.4 °C (2.5 °F).
  • Hectic fever: remittent or intermittent fever, with a difference of 1.4 °C (2.5 °F) or more between peak and trough.[2]

Fever patterns and their clinical significance

The periodicity of fever generally offers little diagnostic value in ascertaining the etiology of fever. Characteristic fever patterns include:[3]


  1. Febricula, definition from Biology-Online.org, consulted June 7, 2006 http://www.biology-online.org/dictionary/Febricula
  2. Musher, D. M.; Fainstein, V.; Young, E. J.; Pruett, T. L. (1979-11). "Fever patterns. Their lack of clinical significance". Archives of Internal Medicine. 139 (11): 1225–1228. ISSN 0003-9926. PMID 574377. Check date values in: |date= (help)
  3. Isaac, Benedict (1991). Unexplained fever : a guide to the diagnosis and management of febrile states in medicine, surgery, pediatrics, and subspecialties. Boca Raton: CRC Press. ISBN 9780849345562.