Influenza Symptoms

  • Symptoms

    The flu typically produces a high fever (from 101° to 103°F), a deep and persistent cough, headache, muscle aches, sore throat, weakness or fatigue, and sometimes sneezing and a runny nose. Patients may cough up sputum, which is mucous-like material from the respiratory tract. Blood in the sputum should be reported to the doctor. The cough may last for a week or longer. The fever usually starts to go down after two or three days, but still may last a week. Patients typically complain of muscle aches in the legs and lower back, but soreness could develop in any muscle or in the joints. (It is unknown why the respiratory disease causes symptoms throughout the body.) Patients may also experience a burning sensation in the eyes or an increased sensitivity to the sun.

    Flu symptoms tend to follow a pattern that distinguishes it from a common cold—for example, a cold usually does not cause a high fever Table 01.

    Table 1.  How To Tell A Cold From the Flu

    Symptoms Cold Flu
    Fever Rare Characteristic, high (102?-104?F); lasts 3-4 days
    Headache Rare Prominent
    General aches, pains Slight Usual; often severe
    Fatigue, weakness Quite mild Can last up to 2-3 weeks
    Extreme exhaustion Never Early and prominent
    Stuffy nose Common Sometimes
    Sneezing Usual Sometimes
    Sore throat Common Sometimes
    Chest discomfort, cough Mild to moderate; hacking cough Common; can become severe

    Adapted from "Is It a Cold or the Flu?" from the National Institute of Allergy and Infectious Diseases, National Institutes of Health, U.S. Department of Health and Human Services.

    Flu symptoms usually come on suddenly. People can often pinpoint the exact time they became ill. However, the disease can also start gradually. Patients become sick from one to four days after being exposed to the influenza virus.

    Difficulty breathing, rapid breaths, and a bluish skin discoloration indicate a serious lung complication. Anyone who has these symptoms should contact a doctor immediately. Nausea, vomiting, and diarrhea may occur with the flu, but are not the main symptoms. Nausea, vomiting, and diarrhea are also symptoms of the somewhat misleading term “stomach flu” (gastroenteritis), which is not caused by the influenza virus. Stomach flu symptoms are caused by other viruses, bacteria, and certain other disorders.

  • Risk Factors

    Being with someone who has the flu increases your risk of coming down with the disease. Because the flu is a contagious disease, contact with people who already have the flu increases your chances of becoming sick. Healthcare workers are at greater risk of acquiring the flu. Outbreaks of influenza B often occur in schools, military installations, and long-term care facilities for older adults.

    Children are two to three times more likely to get the flu than adults. The flu is more common among children and in families with children than in the rest of the population. Children suffering from the flu may have convulsions due to high fevers, and the flu may be followed by ear infections in young children. Children with asthma are at particular risk for developing respiratory complications, including the flu.

    Advanced age and chronic heart and lung conditions place people at increased risk for complications and death, as do some kidney and immune diseases. People with heart and lung diseases requiring ongoing medical care are more likely than others to develop pneumonia and other serious complications of the flu. People with immune diseases such as AIDs or suppressed immune systems, such as people receiving chemotherapy for cancer, are also at increased risk of complications. The majority of flu deaths occur among older people.

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