You wake up in the middle of the night, shaking. You experience a
a fever — a temporary spike in body temperature.
Fevers can occur as the body’s immune system fights infection, but they can also be triggered by other things, including
autoimmune diseases like rheumatoid arthritisor occur as a side effect of some medicines.
But what happens in the body during a fever?
Human body temperature it varies slightly from day to day and from person to person, but usually stays around 98.6 degrees Fahrenheit (37 degrees Celsius). This creates the ideal environment for our cells to work effectively. Part of the brain called hypothalamus acts as a thermostat, constantly monitoring body temperature and turning internal dials to bring it down to approximately 98.6F.
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During an infection, when our immune cells detect foreign invaders such as
bacteria or virusesthey release fever-inducing chemicals called pyrogens. These chemicals travel to the brain where they act temperature-sensitive neurons in the hypothalamus, essentially telling it that it’s time to turn up the heat in the house, Dr. Paul O’Rourkeassistant professor of medicine at Johns Hopkins University, told Live Science.
As a result, these neurons release hormone-like substances, the so-called
prostaglandins — specifically, one called PGE2 — to turn the dial on the body’s thermostat and initiate a fever.
“Usually we consider it a fever when you reach temperatures above 38 degrees Celsius [100.4 F]O’Rourke said.
The hypothalamus can increase body temperature in several ways. For example, directs
blood vessels to constrict, which reduces the amount of heat that is dissipated through the skin’s surface. It also evokes trembling to generate as much heat as possible.
These physiological processes together form part of the body’s first line of defense against infection, known as acute
inflammation. The main goal is to bring the infection under control and stop its spread.
Paradoxically, people can have chills along with a fever, even though their body temperature is rising. This is because the hypothalamus has temporarily increased the body’s internal thermostat to a
higher “normal” level. As your body tries to reach this new baseline, you feel relatively cold.
So why does the body need heat?
One possible reason is to make it harder for bacteria or viruses to replicate and infect our cells, O’Rourke said. A higher body temperature can also make the immune system better “
fighting machine” he said. For example, when our body temperature rises, cells produce heat shock proteins (HSPs) that activate immune pathways to fight infection. HSPs are normal upregulated by cells during inflammationas the body seeks to protect itself from foreign invaders.
“For your average older child or adult, you might experience some degree of fever for a few days, certainly two or three days, without necessarily getting a lot of medical attention,”
Dr. Kitty O’Hareconsultant in the Department of Medicine at Duke University, told Live Science.
But if you’re concerned about your symptoms or they don’t seem to be improving, you should contact your health care provider, she said.
Sometimes when children get a high fever, for example, they may experience convulsions called convulsions
febrile seizures. Although they can be frightening, they usually only last a few minutes and are usually harmless. However, parents should call their health care provider any time their child has a seizure, even if it’s during a fever, O’Hare said.
The degree of the fever also matters, O’Hare said. “It’s good to get advice from your own health care provider based on your health history about how much fever would be problematic for you,” she said.
Depending on your age, over-the-counter medications such as acetaminophen or ibuprofen can help relieve fever symptoms. Removing a layer of clothing, taking a cold bath and drinking cool liquids can also help improve the temperature, she said.
Raising your body temperature during a fever takes a lot of effort—for every 1.8 F [1 C] increase in body temperature, you spend extra
10% more energy than you normally use to maintain your temperature. That’s why it’s important to stay well rested, O’Rourke said.
This article is for informational purposes only and is not intended to offer medical advice.
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