According to the CDC, the duration of the flu typically lasts a few days to less then 2 weeks, varying from person to person. Seasonal flu is a contagious respiratory illness caused by influenza viruses. It can cause mild to severe illness, and can even lead to death. The flu virus is spread from person to person through coughing, sneezing, or speaking from people with influenza. Furthermore, the CDC states that most healthy adults are contagious beginning one day before symptoms begin and up to five to seven days after becoming sick. It is possible to pass the illness on to others before one even realizes they are sick.
The duration of flu varies from person to person because each person's immune system is different. Some people are able to fight off the virus faster than others, so their duration of the flu may be only a few days. Others, especially children 6 to 60 months of age, pregnant women, people 50 years of age or older, people with chronic medical conditions, or people who live in nursing homes and other long term care facilities, may see the duration of flu last for up to 14 days or more.1
Often, people think they have seasonal flu when they really have the common cold. Influenza tests, like the QuickVueŽ Influenza A+B Test, are available to help the doctor diagnose within 10 minutes if the patient has the flu or not. This can potentially reduce the need for any further testing. If the diagnosis of flu is caught within the first 48 hours, the doctor may initiate a treatment. According to the CDC, benefits from antiviral treatment, such as Tamiflu, is strongest when started within 48 hours of the onset of the illness. Catching the flu early may reduce the duration of flu a patient experiences.2
1http://www.cdc.gov/flu/keyfacts.htm
2http://www.cdc.gov/flu/about/disease/symptoms.htm