Fever also called Pyrexia or Febrile Response is one of the common medical signs of most diseases. It is characterized by rise in body temperature. The normal range of body temperature is 97.7 to 99.5 degree F.

Elevation in temperature also starts Muscle Chills. When temperature rises, there is a sudden feeling of cold despite the increase in temperature but as soon as the new temperature is reached there is feeling of warmth. Fever is quite different from Uncontrolled Hypothermia. It causes the elevation of body temperature due to Excess heat production or insufficient thermoregulation at Thermoregulatory Set-Point.


Based on the diagnosis of temperature changes following are the types of Fever.

  • Continuous Fever:  In this type of fever, the temperature remains above normal throughout the day and doesn’t fluctuate more than 1 degree C. Such type of fever is seen in following conditions:

    • Lobar Pneumonia

    • Typhoid

    • Typhus

    • Urinary Tract Infection

  • Intermittent Fever: In this type fever, there is an increase in temperature for certain period of time. Eventually, the temperature returns back to normal. It has further three type.

    • Quotidian Fever having periodicity of 24 hours. For example, fever seen in Plasmodium Knowlesi Malaria.

    • Tertian Fever having periodicity of 48 hours. For example fever seen in Plasmodium Ovale Malaria.

    • Quartan Fever having periodicity of 72 hours. For example fever seen in Plasmodium Malaria.

  • Remittent Fever: In this type of fever, the temperature remaining above normal throughout whole day and fluctuates more than 1 degree C. For example fever associated with Infective Endocarditis.

  • Pel-Ebstein Fever is a special kind of Fever that is seen in association with Hodgkin’s Lymphoma. It causes elevation of body temperature for one week and low for other week and so on.

Other than these there is a type of fever that happens in absence of Immune System Functions. This fever is called Neutropenic Fever or Febrile Neutropenia.


Symptoms of fever are linked to what is known as Sickness Behavior which is as follows.

  • Feeling cold

  • Shivering

  • Anorexia (lack of Appetite)

  • Dehydration

  • Depression

  • Hyperalgesia (sensitivity to pain)

  • Lethargy

  • Drowsiness

  • Sweating

In cases of extreme fever symptoms may include

  • Extreme irritation

  • Confusion

  • Delirium

  • Convulsions


Causes of Fever are vast some of which are as follows.

  • Infectious Diseases like Influenza, Malaria, or AIDS.

  • Skin Inflammation for example Boils or Abscess.

  • Immunological Diseases like Sarcoidosis or Inflammatory Bowel Disease.

  • Tissue obstruction occurring in Surgery, Crush Syndrome or Hemolysis.

  • Reaction to incompatible blood products.

  • Cancers commonly including Kidney Cancer or Leukemia.

  • Metabolic Disorders like Gout or Porphyria.

  • Thrombo Embolic Processes like Pulmonary Embolism or Deep Venous Thrombosis.


Fever generally does not need treatment as most people recover without medical attention. If the Fever rises to dangerous level than following measures must be taken.

Conservative Measures:

  • Sponging or bathing with tepid water.

  • Use of fan or air conditioning to reduce temperature.

  • If the temperature elevates to extreme level of Hyperpyrexia aggressive cooling is necessary.

  • Adequate hydration.


Medications that control the Fever are called Antipyretic. These medications includes ibuprofen, Aspirin and Acetaminophen (Paracetamol).