How do fevers occur?

Fevers occur when the body's internal thermostat, located in the hypothalamus of the brain, is reset to a higher temperature. This can be caused by a variety of factors, most commonly infection or inflammation.

Infection: When the body is fighting an infection, the immune system releases chemicals called pyrogens. These pyrogens travel to the hypothalamus and cause it to raise the body's temperature. This increased temperature helps to kill the bacteria or viruses that are causing the infection.

Inflammation: Inflammation is another common cause of fever. When tissue is damaged, chemicals are released that cause the blood vessels in the area to dilate and become leaky. This allows fluid and white blood cells to enter the tissue, which causes swelling and pain. The increased blood flow to the area also causes the temperature of the tissue to rise.

Other causes: In addition to infection and inflammation, a variety of other factors can cause fever, including:

* Certain drugs, such as antibiotics and chemotherapy drugs

* Cancer

* Autoimmune diseases

* Heat stroke

* Dehydration

How fevers work: When the body's temperature is raised, a number of physiological changes occur. These changes include:

* Increased heart rate and breathing rate

* Dilated blood vessels

* Sweating

* Shivering

* Reduced appetite

These changes help the body to fight off infection and promote healing.

When to seek medical attention: In most cases, fevers are not a cause for concern and will resolve on their own within a few days. However, it is important to seek medical attention if:

* The fever is higher than 104 degrees Fahrenheit

* The fever lasts for more than 3 days

* The fever is accompanied by other symptoms, such as rash, headache, vomiting, or diarrhea

* The person with the fever is an infant or has a weakened immune system