Medical Definition of Flu
Flu: Flu is a colloquialism for influenza. The flu is an acute respiratory illness caused by influenza viruses A or B . Most people who get the flu recover completely in 1 to 2 weeks, but some people develop serious and potentially life-threatening medical complications, such as pneumonia. Much of the illness and death caused by influenza can be prevented by annual influenza vaccination.
Last Editorial Review: 5/13/2016
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