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Flu

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Definition

The flu is a contagious infection of the nose, throat, and lungs caused by the influenza virus.

Symptoms

The flu usually begins abruptly, with a fever between 102 and 106 °F. (An adult typically has a lower fever than a child.) The fever usually lasts for a day or two, but can last 5 days.

Other common symptoms include:

  • Body aches
  • Chills
  • Dizziness
  • Flushed face
  • Headache
  • Lack of energy
  • Nausea
  • Vomiting

Somewhere between day 2 and day 4 of the illness, the "whole body" symptoms begin to subside, and respiratory symptoms begin to increase.

The most prominent of the respiratory symptoms is usually a dry, hacking cough. Most people also develop a sore throat and headache. Runny nose (nasal discharge) and sneezing are common.

These symptoms (except the cough) usually disappear within 4 - 7 days. Sometimes, the fever returns. The cough and tiredness usually last for weeks after the rest of the illness is over.

Other symptoms may include:

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Related Articles

Fever
Fever is the temporary increase in the body's temperature, in response to some disease or illness. A child has a fever when their temperature is at or above one of these levels: 100.4 F (38 C) measured in the bottom (rectally; 99.5 F(37.5 C) measu...  More »
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Headache
A headache is pain or discomfort in the head, scalp, or neck. Serious causes of headaches are extremely rare. Most people with headaches can feel much better by making lifestyle changes, learning ways to relax, and occasionally by taking medicatio...  More »
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Cough
Coughing is an important way to keep your throat and airways clear. However, excessive coughing may mean you have an underlying disease or disorder. Some coughs are dry, while others are considered productive. A productive cough is one that brings...  More »
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