Fever
Fever, also known as pyrexia, is a medical symptom which describes an increase in temperature to levels which are above normal (37 degrees Celsius). An adaptive mechanism, fever is the body's reaction to pathogens; it attempts to kill them by overheating them. Most fevers are caused by infections and almost all infectious diseases cause fever. When a patient has or is suspecting of having a fever, that person's body temperature is measured using a thermometer.
Fever usually occurs in response to pyrogens (e.g. prostaglandins) which are released from inflammatory cells. These pyrogens act on the hypothalamus (the body's thermostat), resetting it to a higher temperature and in doing so invoking the body's temperature raising mechanisms and raising the body temperature to a level above normal. The body has a number of techniques to raise its temperature.
- Shivering ,which involves physical movement that produces heat.
- Vasoconstriction, which entails the constriction of blood flow beneath the skin and thus reduces the amount of heat lost from the body.
The body's temperature is maintained at that level until the effects of the pyrogens wear off.
Pyrexia can be classed as low grade (38 to 39 °C), moderate (39 to 40 °C), or high grade (more than 40 °C) depending on how much the body temperature has deviated from normal.
It may be of benefit and is part of the body's response to a disease; however, if the fever goes above 42 °C then it may cause significant tissue damage and would most certainly be harmful.
Drugs that reduce fever are known as antipyretics. Common antipyretics are acetaminophen, also called paracetamol, and aspirin.
Sometimes, for health reasons, mild fevers are intentionally induced. Cancer cells, for example, are known to die at lower temperatures than normal body cells, and therefore can sometimes be fought with fevers. [1]
US National Institute of Health factsheet BUPA factsheet
- Fever is also the name of an album by Kylie Minogue.
- Fever is also the name of a rock'n'roll song composed by Otis Blackwell