Harmful Effects of Fever
They may come into play in instances of high temperature, especially if the fever lasts too long, and the patients happen to be suffering from some other disease as well. Increased basal metabolism, minute heart volume, and water and salt losses may complicate other basic illnesses. Very high temperatures suppress immune mechanisms.

Utility of Fever
Fever increases immune reactions, and chemotactic, phagocytic, and bactericidal activity of leucocytes. Up to a certain value, it stimulates the processes of antibody production. It slows down the proliferation of microorganisms as well. Increased body temperature causes a decrease in the amount of plasmatic iron, zinc, and copper. This decrease is not favorable for the growth of microbes. High temperature causes destruction of lysosomes and the whole cells.