Should you always treat a fever? The symptom that puzzled doctors for millennia
Fevers are an evolutionarily conserved defence that signal an activated [[immune system]] and have helped animals for more than 600 million years to fight infections; by raising the body's set point via the [[hypothalamus]] they make conditions less hospitable for bacteria and viruses and boost immune-cell function. Historically misunderstood until [[Louis Pasteur]] and germ theory reframed fever as a symptom of infection, not a disease itself. Mild, short-lived [[fever]] often aids recovery and encourages rest and behavioural changes that limit transmission, whereas uncontrolled heat (hyperthermia above about 40C) can cause dehydration, DNA damage, organ dysfunction and, in young children, [[febrile seizures]]. Suppressing fevers with medication can sometimes increase spread at a population level, so decisions about antipyretics should be individualised and guided by clinicians, who can identify when treatment is necessary.