When we are ill our body fights against the infection with the help of antibodies. In this process of producing more antibodies our body heats up. More the temperature more is the production of antibodies. Substances like pyrogens cause fever. They move through bloodstream and send a message to hypothalamus in brain which controls body temperature. Hypothalamus further sends the message to the body which causes shivering or increase in heart rate etc.
Rise in the temperature of body indicates that our body is sick and fever takes our body to a temperature which is not friendly for the virus in our body and therefore helps us to get well soon.
Now here a big question arises that whether fever should be lowered by taking medicines as from above we come to know that it helps the body in recovering infection?
Fever is not a type of illness or creates any disorder in body it is the indication that there is some other problem or infection in the body.
Sometimes cold or other viruses can cause high fever while serious infections may not cause fever.