The flu is a contagious respiratory illness caused by the influenza virus. It can cause mild to severe illness, and at times can lead to death. The best way to prevent this illness is by getting a flu vaccination each fall.

The flu differs in several ways from the common cold, a respiratory infection also caused by viruses. For example, people with cold rarely get fevers or headaches or suffer from the extreme exhaustion that flu viruses can cause. You can get the flu if someone around you who have flu. You can even get the flu simply by touching a surface like a telephone or doorknob that has been contaminated by a touch from someone who has the flu. The viruses can pass through the air and can enter your body through your nose or mouth. Flu virus typically strikes during the winter months.

Typically, the fever begins to decline on the second or third day of the illness. The flu almost never causes symptoms in the stomach and intestines. The illness that some people often call "stomach flu" is not influenza.

Types of Flu

There are two types of vaccines mainly the "flu shot" which is an inactivated vaccine (containing killed virus) that is given with a needle. The flu shot is approved for use in people older than 6 months, including healthy peoples and people with chronic medical conditions. The nasal-spray flu vaccine made with live, weakened flu viruses (sometimes called LAIV for "Live Attenuated Influenza Vaccine").

About two weeks after vaccination, antibodies develop which protect against the influenza virus. Therefore, you should get vaccinated six to eight weeks before flu season begins in order to prevent getting infected or reduce the severity of flu if you do get it.

Symptoms of flu include

" Fever (usually high)
" Headache
" Extreme tiredness
" Dry cough
" Runny or stuffy nose
" Sore throat
" Muscle aches
" Stomach symptoms, such as nausea, vomiting, and diarrhea.

Complications of Flu

Some of the complications caused by flu include bacterial pneumonia, dehydration, and worsening of chronic medical conditions, such as congestive heart failure, asthma, or diabetes. Children may get sinus problems and ear infections as complications from the flu.