Last Update: 12/3/2021
Influenza (flu) is a contagious respiratory illness caused by influenza viruses. It can cause mild to severe illness. 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.
Flu, also known as the influenza, is a contagious disease that is caused by the influenza virus. It attacks 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. Pneumonia, bronchitis, and sinus and ear infections are three examples of complications from the flu. The flu can make chronic health problems worse.
For a list of groups who are at high risk for complications from flu, see: Who should get the flu vaccine.
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 Won't Work for Cold or Flu (CDC)