700 Children's® – A Blog by Pediatric Experts

Fevers: What They Are and Why They Happen

Oct 01, 2014

At urgent care, we address a wide variety of problems, but one of the most common concerns we discuss with parents is fever. When a child develops a fever, parents are often scared or worried. But understanding what’s happening in your child’s body may help to lessen your fears and prevent you from panicking.

fever is an abnormal elevation of the body temperature. The list of what can cause a fever is long, but infection is by far the most common. In this post, we will focus on fever as the body’s natural response to infection.

When triggered by an infection, a fever is simply one symptom of illness. A fever is not the same as a disease.. According to research, a fever is one of the methods that the body is using to try to defeat the infection.

Let’s use a real life example to walk through what typically occurs in the body in response to a fever. Jack is my toddler son, and let’s just say that he isn’t always the most hygienic. When little Jack is at the park one afternoon, he decides to lick the rung of the playground ladder. Soon, Jack gets infected with a cold virus from the child who had just wiped his nose with his hand and climbed the same ladder earlier that day. Over the next few days, the cold virus multiplies and produces chemicals that trigger fever, which are known as pyrogens.

Pyrogens are made by viruses, bacteria or the body itself — in this example, a cold virus. Pyrogens travel to a part of the brain called the hypothalamus, which controls the body’s “thermostat”. The hypothalamus usually keeps the body at a happy 98.6F, but the pyrogens send a message to increase the thermostat to a higher temperature, like 102F. This abnormal elevation of the body temperature is what’s known as a fever.

Because of the message from the pyrogens, the body kicks into high gear to achieve the new desired temperature of 102F. This means doing all the things your body might do if you were out in the winter cold without a coat

  • Conserving heat by bringing more blood into the core
  • Constricting the blood vessels in the skin to minimize heat loss
  • Generating heat by making the muscles shake (shivering)

Jack is now fussy because he feels cold, his hands and feet are cold to the touch, and he is shivering. When a fever is in full force, children can experience many other symptoms, such as body aches, headaches and mild dizziness.

Because Jack has a fever and is clearly uncomfortable, I decide to give him ibuprofen to bring his fever down. Once the medication starts working, the hypothalamus gets the message to bring the body’s temperature back to normal. This means that the body sweats to release heat and blood vessels in the skin dilate, causing the skin to look flushed or red, Often times, heart rate increases to pump the body’s blood around for faster cooling, and breathing can speed up as well.

Jack’s shivering has stopped, he is flushed and sweaty, and his heart is pounding away… but now he is playing and his mood is improving since his temperature is closer to normal. He is a happy little guy now . . . until the cycle repeats itself, which it likely will until his immune system starts to win the battle against the virus.

In our next post on fevers, we’ll explain how to treat your child’s fever and when to go see your pediatrician.

Featured Expert

Heather Battles, MD
Emergency Medicine

Dr. Heather Battles starts her days as a mom of four and ends them as an urgent care physician for Nationwide Children’s Hospital’s Westerville Close To Home clinic.

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Pediatric News You Can Use From America’s Largest Pediatric Hospital and Research Center

700 Children’s® features the most current pediatric health care information and research from our pediatric experts – physicians and specialists who have seen it all. Many of them are parents and bring a special understanding to what our patients and families experience. If you have a child – or care for a child – 700 Children’s was created especially for you.