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Why does your body temperature rise when you have the flu?

Stacy Wiegman, PharmD
Stacy Wiegman, PharmD
Pharmacy
answer
Your body temperature rises when you have the flu as a way of fighting off the influenza virus; viruses thrive best at 98.6 degrees Fahrenheit—normal body temperature. When your body is hotter it's harder for the flu virus to survive. A fever also stimulates your immune system to fight off the illness. Although you may not feel great when you have a fever, the fever itself is helping you get better.
Discovery Health
Discovery Health
answer

When the body temperature rises because of an infection, it's called fever. Fevers are caused by chemicals in the bloodstream called pyrogens. Pyrogens make their way to the brain's hypothalamus, which is in charge of regulating body temperature. When those pyrogens bind to certain receptors in the hypothalamus, the body temperature rises.

One common pyrogen is Interleukin-1 (also called IL-1). IL-1 is produced by white blood cells that are called macrophages when they connect with certain bacteria and viruses. IL-1 has multiple purposes. An important purpose is to signal white blood cells, called helper T cells, into action.

Doctors think one reason for a fever is to raise the body's temperature enough to kill off bacteria and viruses that are sensitive to temperature changes. In debate right now is whether we should be trying to lower fevers. Aspirin, for example, will reduce fever. Still, if the fever is helping rid the body of infection, then lowering it could be counterproductive. On the other hand, people sometimes die from fever. The general medical consensus right now leans to the "reduce the fever" side of the fence.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.