Fevers: Their cause and potential dangers

[note: yes, if I still have this stupid fever tomorrow, I will go to the doctor, blah blah blah.]

As I sit here with this annoying fever in the low 100 degree range (my normal temp is in the upper 97 degree range), I am wondering about the mechanism that causes fevers. This one so far isn’t coming with any respiratory or throat symptoms, as mine usually do, just muscle aches, chills, and overly sensitive-to-the-touch skin.

So what causes the darn things? Feel free to get geeky and technical on me. Also, is there any danger to leaving a not-terribly-high fever alone for a couple of days (i.e. not taking ibuprofen every few hours), other than feeling generally crappy? Is the fever per se going to damage anything, provided it doesn’t go to 105 or something? Just curious.

Fevers can be caused by a couple of things. In your case, most probably by chemicals known as pyrogens. The body’s temperature is regulated by part of the hypothalamus. When you are infected with bacteria, virus, fungus, etc they release these pyrogens and the hypothalamus responds by increasing the body’s ‘set point’, similar to turning up the thermostat in your house. So the thermostat may be set at 101F, but the body is still at 98.6F. What do you do? You start shivering to increase your body’s temperature until it is at the set point (like the heater kicking in at your house). Similarly when you’ve fought off the infection and the set point is back to normal, you will start sweating to bring your body temperature back to the set point. This is known as the ‘fever breaking’

Fevers in themselves are NOT harmful and may actually be beneficial to a certain degree (pun intended). The body is more efficient at fighting off intruders at slightly elevated temperatures. Temperatures under 104 are generally harmless aside from making you feel like crap, which makes you stay at home in bed (something you should be doing anyway). Over 104 and it becomes more worrisome for organ damage or seizure, especially in infants and children.

Decent article from eMedicine.