Influenza is a contagious respiratory illness caused by influenza viruses. It can cause mild to severe illness. Serious outcomes of flu infection can result in hospitalization or death. Some people, such as older people, young children, and people with certain health conditions, are at high risk of serious flu complications. The best way to prevent the flu is by getting a flu vaccine each year.
Signs and symptoms
People who have the flu often feel some or all of these signs and symptoms that usually start suddenly, not gradually:
- Fever or feeling feverish/chills
- Sore throat
- Runny or stuffy nose
- Muscle or body aches
- Fatigue (very tired)
- Some people may have vomiting and diarrhea, though this is more common in young children than in adults.
How it spreads
Most experts believe that flu viruses spread mainly by tiny droplets made when people with flu cough, sneeze or talk. These droplets can land in the mouths or noses of people who are nearby. Less often, a person might also get flu by touching a surface or object that has flu virus on it and then touching their own mouth, nose, or possibly their eyes.
You may be able to pass on the flu to someone else before you know you are sick, as well as while you are sick. Although people with the flu are most contagious in the first 3-4 days after their illness begins, some otherwise healthy adults may be able to infect others beginning 1 day before symptoms develop and up to 5 to 7 days after becoming sick. Some people, especially young children and people with weakened immune systems, might be able to infect others with flu viruses for an even longer time.
Complications of flu can include bacterial pneumonia, ear infections, sinus infections, and worsening of chronic medical conditions, such as congestive heart failure, asthma, or diabetes.
The first and most important step in preventing flu is to get a flu vaccination each year. CDC also recommends everyday preventive actions (like staying away from people who are sick, covering coughs and sneezes and frequent handwashing) to help slow the spread of germs that cause respiratory (nose, throat, and lungs) illnesses, like flu.
If you get the flu, antiviral drugs may be a treatment option.
Check with your doctor promptly if you are at high risk of serious flu complications and you get flu symptoms. People at high risk of flu complications include young children, adults 65 years of age and older, pregnant women, and people with certain medical conditions such as asthma, diabetes and heart disease.
When used for treatment, antiviral drugs can lessen symptoms and shorten the time you are sick by 1 or 2 days. They also can prevent serious flu complications, like pneumonia. For people at high risk of serious flu complications, treatment with antiviral drugs can mean the difference between milder or more serious illness possibly resulting in a hospital stay.