What are flu symptoms?

Typical clinical features of influenza include

• fever (usually 100° F to 103° F in adults and often even higher in children),
  
• respiratory symptoms such as
  
• cough,
  
• sore throat,
  
• runny or stuffy nose,
  
• headache,
• muscle aches, and
  
• fatigue, sometimes extreme.
  

Although nausea, vomiting, and diarrhea can sometimes accompany influenza infection, especially in children, gastrointestinal symptoms are rarely prominent. The term "stomach flu" is a misnomer that is sometimes used to describe gastrointestinal illnesses caused by other microorganisms.

Most people who get the flu recover completely in one to two weeks, but some people develop serious and potentially life-threatening medical complications, such as pneumonia. In an average year, influenza is associated with about 20,000 deaths nationwide and many more hospitalizations. Flu-related complications can occur at any age; however, the elderly and people with chronic health problems are much more likely to develop serious complications after influenza infection than are younger, healthier people.