Definition of fever —

  • fever is an increasing of body temperature above normal under the influence of thermo regulatory center.
Abnormal elevation of temperature. The normal temperature taken orally ranges from about 97.6° to 99.6°F, although there is some individual variation. Rectal temperature is 0.5° to 1.0°F higher than oral temperature.

normal body temp —

  • fever is controlled by hypothalamus
  • normal core body tmp is 37 C
  • mean oral temp is- 36.8 C
  • mean temp is least at morning 6am
  • maximum at  4 pm

body temperature in fever —

  • morning temp is more then– 37.2C
  • and earning temp  more then–37.7C
  • oral temp is 1F higher then axially temp
  • during menstruation the morning temp in women is lower in 1st 2nd weeks

site of temperature measurement —

  • oral cavity
  • axillary
  • rectum
  • tympanic membrane [radiant heat]
  • average rise of 1F there is increase of 10 beat in pulses

Etiology  of Fever —

  • Elevated temperatures that are caused by inadequate thermoregulatory responses during exercise in very hot weather is called hyperthermia; the set point is not increased.
  • Fever involves resetting the temperature set point that the body seeks to maintain at a higher level.
  • It is caused by the release of interleukin-1 (IL-1), interleukin-2 (IL-2),
  • and tumor necrosis factor from white blood cells, esp. macrophages, secretion of acute phase proteins, and redistribution of the blood away from the skin by the autonomic nervous system.

Relative bradycardia —

  • when the temp is increasing but the pulse are not increasing this condition called relative bradycardia
  • main causes of this condition—typhoid fever, leptospirosis, brucellosis, factitious fever, some time drug induced

Difference between fever, hyperthermia, hyperpyrexia —


  • in fever there is increase in body temperature along with hypothalamic thermo regulatory set point.

Hyperthermia —

  • uncontrolled rise in body temperature but unchanged thermo regulatory set point.

Hyperpyrexia –

  • fever of  more then– 41C (106.7F) is called hyperpyrexia.
  • causes are—infection, CNS haemorrhage, etc.


  • hyperthermia dose not respond to aspirin and paracetamol.
  • hyperpyrexia and fever both respond to paracetamole and aspirin.

Main causes of hyperthermia —

  • septic shock
  • bacterial infection
  • thyrotoxoicosis
  • pheochromocytoma
  • MAO induced
  • tricyclic anti depressant drug induced
  • amphetamines
  • LSD
  • cocaine induced
  • malignant hyperthermia
  • some time by anaesthetics, succnyl choline.

Heat stock —

  • the failure of thermoregulatory mechanism in body can cause the heat stoke. it may be exortional or non exortional.

Patterns of fever —

  • continuous fever–

  • there is continuous fever with the fluctuation of only 1F . temperature never touch normal.
  • remittent fever–

  • there is persistent fever but the fluctuation is more then  1F.
  • Intermittent fever–

  • the temperature of body comes to normal during the certain time of day.
  • Qtidian fever–

  • it is intermittent fever but it occurs daily.
  • Tertian fever–

  • fever occurs 1st day and then 3rd day.
  • Quartan fever–

  • fever ocure 1st day then 4th day.
  • Pel ebstein fever–

  • fever  3- 10 day then no fever next  3- 10 day, like in Hodgkin’s lymphoma.
  • Cyclic neutropeniya–

  • the fever occur every 21 day.

Treatment of fever —

  • the best anti pyretic is paracetamol that can be used.
  • aspirin is not used due to risk of Reye’s syndromes [ in influenza in children age blow 15 y, then there is vomiting, progressive CNS damage, hepatic injury,

Treatment of hyperpyrexia —

  • oral anti pyretic,
  • cooling blanket

Treatment of hyperthermia —

  • sponging
  • fans, cooler, Ac, ice boatel, cooling blanket,
  • IV fluid, gastric and peritoneal lavages  with iced saline, haemodialysis, etc.
  • this is the general information about fever, hope it will help you…


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