February 18, 2024 at 10:49 am

Here’s What Happens Inside Your Body When You Have A Fever

by Trisha Leigh

Source: Shutterstock

Nobody like to have a fever. In fact, we’ve kind of made fevers this terrifying thing, especially when it comes to children, because of the scary stuff that can happen if our body temperature gets too high.

In truth, running a reasonable fever is nothing to fear – and in fact, might even allow your body to fight off invading bacteria or viruses more quickly.

Along with defending against foreign microbes, fevers can arise in autoimmune conditions or even as a side effect of some drugs.

Normally, our bodies maintain a core temperature around 98.6 degrees, which is an optimal temperature when it comes to how our cells work. The hypothalamus regulates that temperature, keeping it steady as long as it’s possible.

Source: Shutterstock

Once our immune cells detect invading bacteria or viruses, though, they release chemicals called pyrogens. These induce fevers by traveling to the brain and working on the temperature-sensitive neurons in the hypothalamus.

Dr. Paul O’Rourke, a professor of medicine at Johns Hopkins, says then those neurons release prostaglandins (specifically PGE2) that actually initiates the fever.

“We typically consider a fever when you’re reaching temperatures greater than 38 degrees Celsius (100.4F).”

The hypothalamus can raise your body’s temperature by directing blood vessels to constrict, which reduces the amount of heat that can leave through your skin. It can also induce shivering, which generates more heat.

Together this inflammation is the body’s first line of defense against infection – with the main goal being to stop it from spreading.

Source: Shutterstock

You might be wondering why the body needs the heat as part of its defense.

One theory is that it makes it harder to replicate and infect our cells, but it could also help the immune system in its fight.

Cells produce heat shock proteins (HSPs) that activate immune pathways and are upregulated by cells during inflammation.

“For your average older child or adult, you may experience a degree of fever for a few days, certainly two or three days, without necessarily needing to get a lot of medical attention.”

If your symptoms don’t seem to be improving after that, you might want to see a doctor.

Additionally, young children can experience febrile seizures if their temperature gets too high, and if you notice them, a healthcare provider should be notified.

Source: Shutterstock

A doctor should be able to give you a range where the degree of the fever would be concerning.

Most often, though, removing a layer of clothing, taking a cold bath, having a cold drink, and getting plenty of rest should alleviate the symptoms while you wait for your body to reduce its temperature within a few days.

Remember that your body is working hard to increase its temperature – around 10% more energy than you would normally use – so that rest part isn’t exactly optional.

Don’t feel badly taking some time off while your body does the work.

If you found that story interesting, learn more about why people often wake up around 3 AM and keep doing it for life.