Influenza (flu) is an infection in the lungs and breathing passages. It is caused by the influenza virus. There are different strains, or types, of the flu virus from year to year. Unlike the common cold, the flu comes on suddenly and the symptoms, such as a cough, congestion, fever, chills, fatigue, aches, and pains, are more severe. These symptoms may last up to 10 days. Although the flu can make you feel very sick, it usually doesn’t cause serious health problems.
Home treatment is usually all you need for flu symptoms. But your doctor may prescribe antiviral medicine to prevent other health problems, such as pneumonia, from developing. Older people and those who have a long-term health condition, such as lung disease, are most at risk for having pneumonia or other health problems.