Is a fever harmful or helpful?

The answer

Fever is an evolutionarily conserved immune response, present in fish, reptiles, and mammals, that actively raises body temperature to fight infection. A temperature increase of just 1 to 4 degrees Celsius enhances the activity of immune cells, increases antibody production, and accelerates the movement of white blood cells to infection sites. Many pathogens reproduce optimally at normal body temperature (37 degrees Celsius) and are impaired at higher temperatures. Studies show that treating mild fevers with antipyretic drugs can actually prolong some infections. However, extremely high fevers above 41 degrees Celsius (106 degrees Fahrenheit) can be dangerous, potentially causing protein denaturation and organ damage, which is why the body has built-in temperature limits regulated by the hypothalamus.