Summary
A raised body temperature that can slow pathogen growth and boost immune activity.
In depth
Pyrogens such as IL-1 and IL-6 reset the hypothalamic set point. Higher temperatures reduce bacterial growth and boost immune responses. Very high fever above about 41 °C can be dangerous.
Prostaglandin E2 acts on the hypothalamus. Antipyretics (paracetamol, ibuprofen) block its synthesis. Febrile seizures can occur in young children.
Remember: fever is a symptom, a part of the defence, not a disease.
Fever is a regulated rise in body temperature, unlike hyperthermia where the set point is unchanged. Prostaglandin E2 acts on the hypothalamus. A rise of 1 to 2 degrees speeds up immune cell activity and makes iron less available to bacteria. Chills and shivering occur as the body raises its temperature to the new set point, and sweating follows when the set point falls (the fever breaks).
Antipyretics (paracetamol, ibuprofen) block prostaglandin synthesis and help comfort, though fever itself is not usually dangerous below about 40 degrees. Children can get febrile seizures. Fevers above 41 degrees, or those with confusion or stiff neck, need urgent care. Periodic fevers are typical of malaria.
Frequently asked questions
What is Fever?
A raised body temperature that can slow pathogen growth and boost immune activity.
Which area of biology covers Fever, and how advanced is it?
Fever is one of the 52 topics in Immunology & Disease. It is rated Beginner, so it suits learners who are starting out in biology. Related topics in this area include Herd Immunity, Antigens, Basic Reproduction Number.
Why does Fever matter?
Fever is part of the body's defence, and lowering it is not always required.
Can you give an example of Fever?
Shivering raises body temperature at fever onset.
What should I learn before Fever?
Fever is a Beginner topic, so no earlier topic is required. Other Beginner topics in Immunology & Disease that pair well with it include Immune System, Viruses, Innate Immunity.
What topics are related to Fever?
The closest topics to Fever are Herd Immunity, Antigens, Basic Reproduction Number, Vaccines. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Fever?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Fever. To practise the whole of Immunology & Disease, use the Immunology & Disease quiz.
How is Fever different from Herd Immunity?
Fever: A raised body temperature that can slow pathogen growth and boost immune activity. Herd Immunity: Indirect protection of unvaccinated people when enough of a population is immune. Read both side by side and note what each one explains.
How should I study Fever step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Herd Immunity and explain the difference aloud. Finally, take the Immunology & Disease quiz and come back to this page for any question you miss.