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Influenza (Seasonal Flu) - What Happens

Influenza (flu) usually comes on suddenly. In many cases people can pinpoint the hour when symptoms started. Symptoms develop 1 to 4 days after you are infected, and they include:

  • Fever, which lasts for about 3 days. Fever is usually slightly lower on the 2nd and 3rd days but may last up to 8 days.
  • Cough, runny nose, and sore throat, which become more noticeable as fever and other symptoms decrease. These symptoms usually last 3 to 4 days after the fever goes down. A dry, hacking cough may linger for up to 10 days after other symptoms are gone.

Complete recovery may take 1 to 2 weeks or longer. Fatigue and weakness can last for several weeks.

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Flu Shot Failure? Questions & Answers

The CDC reports this year's flu shot may not protect against a strain of influenza that's hitting the U.S. Q. Does this mean the flu shot is useless? Not at all. Although this year's flu vaccine doesn't match two of the three main types of flu strains now in circulation, people who did get a flu shot and catch the flu get a much milder disease. This can make a life-or-death difference to people who are at high risk of flu complications, such as pregnant women, young children, the elderly,...

Read the Flu Shot Failure? Questions & Answers article > >

Complications of influenza may develop in anyone, but they are much more likely in older adults and people who have other health problems, especially heart and lung diseases.

    This information is produced and provided by the National Cancer Institute (NCI). The information in this topic may have changed since it was written. For the most current information, contact the National Cancer Institute via the Internet web site at http:// cancer .gov or call 1-800-4-CANCER.

    WebMD Medical Reference from Healthwise

    Last Updated: January 31, 2014
    This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.
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