Influenza or "flu" is a respiratory illness caused by a flu virus. Flu viruses spread each fall, winter, and spring.
Young (infants) and the very old are most at risk for severe illness from seasonal flu. In the U.S., about 3,000 to 49,000 people die yearly from seasonal flu. The Centers for Disease Control and Prevention (CDC) recommends that everyone age 6 months and older get a flu shot each year.
The flu virus spreads easily. For example, when a person with the flu sneezes, coughs, talks, or laughs, the flu virus can spread into the air as droplets from their mouth or nose. These droplets can spread to people and surfaces within 6 feet.
The flu virus can spread to your hands if you touch anything that has the virus on it. If you then touch your eyes, nose, or mouth, you can get the flu.
The flu virus can live on surfaces, such as countertops and door knobs, for 24 to 48 hours.
Seasonal flu is contagious from 1 day before any signs appear to up to 5 days after you get sick.
Flu spreads easily between people and can live for up to 2 days on surfaces such as doorknobs, tabletops, and counters.
Your health care provider can examine and test you for the flu virus.
Your health care provider may treat you with antiviral drugs. Antiviral drugs are most effective if taken within the first two days of being sick.
People with severe illness from the flu should talk to their health care provider about taking antiviral drugs if they get the flu.
Most people with the flu will not need medical care or antiviral drugs. Most will recover in less than two weeks. Even healthy people can have severe illness from the flu. Adults should get medical help right away if they develop:
Over time, flu can lead to:
Illness from flu can also make other health problems worse. People with asthma may have more asthma attacks. People with heart problems may get worse. Flu can cause severe illness and even death in:
These people should alert their health care provider if they get signs of the flu. They may need early treatment.
Use this flowchart to help decide how to best handle the flu: Flu Self-Assessment Flowchart (573 KB, PDF).
For more on how to clean hands, see Clean Hands.
The best way to avoid the flu is to get a flu shot each year.
Flu can be severe in pregnant women. Get your flu shot. Pregnant women should let their health care provider know if they have any signs of flu. Pregnant women should not take over-the-counter drugs without asking their provider first. The flu shot is safe for pregnant women at any stage of pregnancy.
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