The duration of a fever is as important as how high it is. A high fever for a short period of time is tolerated better than a high fever for a longer period because there is less depletion of body energy reserves. The longer a fever goes, the less stamina a person has. While this varies from person to person, a person with a fever running longer than 4 days with no changes, should see a physician.
How one tolerates a fever then, depends upon how high it goes, how long it lasts, if there is sweating, and how much energy reserve a person has. In general, if the person eats well, tends to have few illnesses, and when they do, illnesses of short duration, and are fairly alert and oriented; they undoubtedly have a strong constitution and will be better able to handle the effects of a fever. They also tend to mount a fever quickly, a sign of a strong immune system.
By contrast the person who is frequently or chronically ill, has poor eating habits or eats poor quality food, and tends to be low energy when not ill is less likely to weather the effects of a fever. He or she will not spike the high temperatures needed to overcome the infection but will tend to have lower fevers which "hold the line" against infective agents but are unable to overcome them. Elderly persons are often in this group as a result of the ageing process, narrow tolerance ranges and generally poor diets.
Ideally a fever will follow a pattern somewhat like this. There is a period of incubation when the infective agent or toxin has taken hold. This is where we first notice that we are getting a cold or flu and are feeling a bit "under the weather". Next, there is an aggravation period when temperature elevation occurs. The person tends to go into "adaptive withdrawal" as chilling often occurs. The destruction period is marked by a sustained high temperature to eliminate the infective agent and toxins. Next is the abatement stage which is characterized by sweating to bring down the fever; as mentioned previously, the fever is said to have "broken" and the person begins to feel better. The reconstruction period is the time when one wants to rest, as the body uses this time to restore its strength and resources.
For the most part fevers follow this pattern. There are exceptions however and different types of fever patterns can point to various infective agents.
Fevers in adults tend to show up differently than in children because "grown ups" often do not allow their body's to fight the infection the way it was designed to. More often than not, adults continue to work and not rest, eat meals even though they may be nauseated or not hungry, take medications to "get rid" of symptoms and, in general, ignore the process. Continuing to ignore the condition will only prolong it and in the long run, make it worse.
It is interesting to note that many of the elderly will undertake actions that act to enhance the body's healing mechanisms similar to those discussed earlier in children. Perhaps this is due to lifestyle patterns learned in early childhood when there were fewer medicines available to counteract fever symptoms. It is also possibly due to instinctual patterns inherent in our body's which are now heeded, as the effects of illness can be much more serious in this age group.
Only through supporting the body and its natural ally, fever, will it be able to overcome the disease or toxic process and simultaneously strengthen the vital force. In the long run it will make for less illness and a longer, healthier life.