Influenza, often called the flu, is a viral infection Overview of Viral Infections A virus is a tiny living organism. Viruses are so small they can be seen only with the most powerful microscopes. That's why they're called microorganisms (micro means very small). Other common... read more that affects your lungs and airways. Flu symptoms are a little bit like the common cold Common Cold The common cold is a viral infection. It's one of the most common illnesses people get. Colds spread easily from person to person, especially within the first 2 days of symptoms Symptoms include... read more but are much more severe.
The flu spreads easily from person to person, sometimes causing epidemics (when many people get sick within a very short time)
The flu causes chills, fever, headache, sore throat, and cough
Most people recover, but flu makes some people very sick and some die from pneumonia Pneumonia Pneumonia is an infection deep in your lungs. The infection involves the small air sacs in your lungs (alveoli). Pneumonia is different from infection of the air passages (bronchi) in your lungs... read more , a bad lung infection
Doctors will have you rest, drink plenty of fluids, and take medicine for your symptoms if needed—sometimes they'll have you take antiviral medicines
People age 6 months or older should get a flu vaccine Influenza Vaccine The influenza virus vaccine helps protect against influenza. Two types of influenza virus, type A and type B, regularly cause seasonal epidemics of influenza in the United States. There are... read more each year to help prevent the flu
The flu vaccine is the best way to prevent the flu, but you need to get a shot each year—the flu virus changes each year, so last year’s shot probably won't prevent this year’s flu
The virus spreads:
Flu season in the United States lasts from November through March. Each year, millions of people get the flu and thousands die.
The flu virus changes a little bit from year to year. These changes can cause problems:
Sometimes the changes in the flu virus make it both more likely to spread and more deadly. This happens a few times every hundred years and causes huge worldwide flu epidemics. These epidemics kill millions of people around the world. Fortunately, because the virus keeps changing, this ultra-dangerous flu eventually changes to a less dangerous one.
Early symptoms of flu include:
Later symptoms include:
Most symptoms go away within a week, but the cough may last for weeks.
Children, pregnant women, older people, people with other diseases such as diabetes, heart disease and lung disease, and people with a weak immune system Overview of the Immune System The immune system is your body's defense system. It helps protect you from illness and infection. The immune system's job is to attack things that don’t belong in your body, including: Germs... read more may have more severe symptoms. They may also get pneumonia Pneumonia Pneumonia is an infection deep in your lungs. The infection involves the small air sacs in your lungs (alveoli). Pneumonia is different from infection of the air passages (bronchi) in your lungs... read more .
Doctors can usually tell if you have flu based on your symptoms, especially if many people in your area have the flu. To know for sure, doctors may test your blood or fluid from your nose or throat for the flu virus.
If doctors think you may have pneumonia, they'll do:
Tell you to get lots of rest and drink plenty of fluids, especially until your fever goes away
Tell you to take certain medicines to help you feel better, such as acetaminophen or ibuprofen for muscle aches and fever, or decongestants for a stuffy nose
Sometimes, give you antiviral medicines, if you’ve had symptoms for just 1 or 2 days
Take these measures:
Almost everyone 6 months and older should get a flu shot Influenza Vaccine The influenza virus vaccine helps protect against influenza. Two types of influenza virus, type A and type B, regularly cause seasonal epidemics of influenza in the United States. There are... read more (vaccine) each year to help prevent the flu. Talk to your doctor about getting a flu shot.
Most flu shots are made using eggs, so people with severe egg allergies need to have a special egg-free flu shot—be sure to tell your doctor if you have an allergy to eggs
It takes 2 weeks for the flu vaccine to work, so doctors in the United States suggest getting it in October, before flu season starts
If you can't safely get a flu shot, doctors may give you antiviral medicine to prevent the flu if there’s an outbreak of flu in your area
Sometimes you still get the flu after you had a flu shot. However, the shot makes getting the flu a lot less likely. Also, many people who think they got the flu after having the shot really just had a bad cold and not the flu.