Fever is one of the body’s natural responses to fight infections. It helps limit the multiplication of microbes (viruses and bacteria) and stimulates the immune response. Acting as a warning signal, it is useful but may require management.
Fever is a symptom defined as an increase in body temperature above the normal value (37.2°C to 37.7°C orally, 0.5°C more if measured rectally or tympanically).
Other causes of increased body temperature include heatstroke, sunstroke, or intense physical activity.
When white blood cells fight microbes responsible for infection, they release proteins called pyrogens*. These act on the nervous system, particularly the hypothalamus, which regulates body temperature, causing it to rise.
* Pyrogen: a substance that induces fever
Fever is often accompanied by:
In adults, moderate fever may go unnoticed or cause a mild sense of discomfort with chills.
Fever has beneficial effects. On the one hand, in the case of an infection, it helps limit the multiplication of microbes; on the other hand, it stimulates the immune response against these infectious agents. However, fever can also have negative effects, as it impacts the body — for example, by increasing respiratory rate and heart rate (by 5 to 9 beats per minute). It may be poorly tolerated, especially when it is high.
Before using fever-reducing medications (antipyretics), it is essential to identify and treat the underlying cause of the fever — for instance, with anti-infective treatment in the case of an infection. In children, fever should be managed when it exceeds 38.5°C and/or is not well tolerated.
Important: If the fever lasts more than 3 days, or if it affects a very young child or elderly person, medical consultation is necessary.
It is composed of the prefix “anti” and “pyretic”, which comes from the Greek “pyretikos”, meaning fever. In other words: “prevents or treats fever.”