Last Update: 5/25/2023
Influenza (flu) is a contagious respiratory illness caused by influenza viruses. It can cause mild to severe illness, including hospitalization and death. Serious flu infections can result in hospitalization or death.
Some people, such as older people, young children, and people with certain health conditions, are at high risk for serious flu complications. The best way to prevent the flu is by getting vaccinated each year.
Not only does the spread of influenza take its toll on health, but also has a significant economic toll. The most recent US economic costs measured for seasonal influenza is $11.2 billion in total direct and indirect costs.
Flu, also known as the influenza, is a contagious disease that is caused by the influenza virus. The influenza virus enters through the respiratory tract in humans (nose, throat, and lungs). The flu is different from a cold. Flu usually comes on suddenly and may include these symptoms:
These symptoms are usually referred to as "flu-like symptoms." Please also see Influenza vs. Colds vs. Pertussis for more information.
Anyone can get the flu, even healthy people, and serious problems from the flu can happen at any age. Most people who get flu will recover in one to two weeks, but some people will develop life-threatening complications as a result of the flu.
People 65 years and older, people of any age with chronic medical conditions, and very young children are more likely to get complications from the flu. Complications for the flu can be sinus and ear infections, bronchitis, pneumonia, hospitalization and death, especially in high-risk groups. The flu can make chronic health problems worse.
High-risk groups are at increased risk for severe flu complications:
People in high-risk groups with flu-like symptoms should seek medical help to prevent flu complications.
Flu is caused by a virus, so antibiotics (like penicillin) don't work to cure it. The best way to prevent the flu is to get a flu vaccine (flu shot) each fall, before flu season. Never give aspirin to children or teenagers who have flu-like symptoms – and particularly fever – without first speaking to your doctor. Giving aspirin to children and teenagers who have the flu can cause a rare but serious illness called Reye syndrome. Children or teenagers with the flu should get plenty of rest, drink lots of liquids, and take medicines that contain no aspirin to relieve symptoms.
About Influenza (CDC)
Childhood Influenza Immunization Coalition (CIIC)
Antibiotics Use for Flu (CDC)
Myths and Facts About Influenza
Influenza Vaccine Safety