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Flu
 Understanding Flu
  2009 H1N1 Flu
  Definitions and Overview
  Cause
  Transmission
  Symptoms
  Complications
  Diagnosis
  Treatment
  Prevention
  Publications
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Flu (Influenza)

Symptoms

If you get infected by the flu virus, you will usually feel symptoms 1 to 4 days later. You can spread the flu to others before your symptoms start and for another 3 to 4 days after your symptoms appear. The symptoms start very quickly and may include

  • Body aches
  • Chills
  • Dry cough
  • Fever
  • Headache
  • Sore throat
  • Stuffy nose

Typically, the fever begins to decline on the second or third day of the illness. The flu almost never causes symptoms in the stomach and intestines. The illness that some call “stomach flu” is not influenza.

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Volunteer for NIAID-funded clinical studies related to flu on ClinicalTrials.gov.

See Also

  • Influenza news releases
  • Common cold
  • Is It a Cold or the Flu?
  • Related Links

    View a list of links for more information about influenza.

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    Volunteer for NIAID-funded clinical studies related to flu on ClinicalTrials.gov.

    See Also

  • Influenza news releases
  • Common cold
  • Is It a Cold or the Flu?
  • Related Links

    View a list of links for more information about influenza.