The flu is an infection of the nose, throat, and lungs. It spreads easily from person to person.
This article discusses influenza types A and B. A type of influenza A infection due to the H1N1 influenza strain is commonly called the swine flu.
The flu is caused by an influenza virus.
Most people get the flu when they breathe in tiny airborne droplets from the coughs or sneezes of someone who has the flu. You can also catch the flu if you touch something with the virus on it, and then touch your mouth, nose, or eyes.
People often confuse colds and flu. They are different, but you might have some of the same symptoms. Most people get a cold several times a year. On the contrary, people generally get the flu only once every few years.
Sometimes, you can get a virus that makes you throw up or have diarrhea. Some people call this the "stomach flu." This is a misleading name because this virus is usually not the actual flu. The flu mostly affects your nose, throat, and lungs.
Flu symptoms often start quickly. You can start to feel sick about 1 to 7 days after you come in contact with the virus. Most of the time, symptoms appear within 2 to 3 days.
The flu spreads easily. It can affect a large group of people in a very short amount of time. For example, students and co-workers often get sick within 2 or 3 weeks of the flu's arrival in a school or workplace.
The first symptom is a fever between 102°F (39°C) and 106°F (41°C). An adult often has a lower fever than a child.
Other common symptoms include:
The fever, aches, and pains begin to go away on days 2 through 4. But new symptoms may occur, including:
Most symptoms go away in 4 to 7 days. The cough and tired feeling may last for weeks. Sometimes, the fever comes back.
Some people may not feel like eating.
The flu can make asthma, breathing problems, and other long-term (chronic) illnesses and conditions worse.
Most people do not need to see a health care provider when they have flu symptoms. This is because most people are not at risk for a severe case of the flu.
If you are very sick with the flu, you may want to see your provider. People who are at high risk for flu complications may also want to see a provider if they get the flu.
When many people in an area have flu, a provider can make a diagnosis after hearing about your symptoms. No further testing is needed.
There is a test to detect the flu. It is done by swabbing the nose or throat. Most of the time, test results are available very fast. The test can help your provider prescribe the best treatment.
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Acetaminophen (Tylenol) and ibuprofen (Advil, Motrin) help lower fever. Providers sometimes suggest that you use both types of medicine. Do not use aspirin.
A fever does not need to come all the way down to a normal temperature. Most people feel better when the temperature drops by 1 degree.
Over-the-counter cold medicines may make some of your symptoms better. Cough drops or throat sprays will help with your sore throat.
You will need a lot of rest. Drink plenty of liquids. Do not smoke or drink alcohol.