Health's Book

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:

* Loss of appetite
* Muscle aches and stiffness
* Stuffy, congested nose
* Sweating
* Worsening of underlying illness, such as asthma or heart failure