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What is influenza? 

Influenza (often called "flu") is a contagious illness caused by the influenza virus. Symptoms include fever, cough, muscle aches, headache, runny nose, sore throat and general weakness. Some people may have vomiting and diarrhea, but this is more common in children than adults. The onset of these symptoms may be sudden. These symptoms can range from mild to severe.

How is flu spread?

The viruses that cause flu live in the nose and throat and are sprayed into the air when an infected person sneezes, coughs or talks. People nearby can then breathe in the virus. Less often, people may also get the flu by touching a surface or object that had the virus on it and then touching their own mouth, eyes or nose.

Flu symptoms usually start 1 to 4 days after a person breathes in the virus, but it can be longer.  Most people can spread the flu virus 1 day before their symptoms begin until about a week afterward.

Is flu dangerous?

It can be dangerous, especially for the very young, the very old and for those with other medical problems. Most people have illness lasting a few days; however, some may develop pneumonia or other serious complications. Every year, flu causes thousands of hospital admissions in the United States. 

How can I prevent the spread of flu?

There are many ways you can help prevent the spread of germs.

  • Everyone 6 months and older should get a flu vaccine every year.
  • Cover your nose and mouth with a tissue every time you cough or sneeze. If you don't have a tissue, sneeze or cough into your upper sleeve. 
  • Clean your hands often with soap and water or an alcohol-based hand cleaner.
  • Clean surfaces in your home regularly with a household cleaner.
  • Avoid close contact with people who are sick when possible.
  • Stay home when you are sick.  A person with flu should stay home for 24 hours after their fever has gone away without the use of fever reducing medicine. For most people, this will be a minimum of 4 days.  

Who should get a flu vaccine?

It is recommended that everyone 6 months of age and older get a flu vaccine. A person needs to get a flu vaccine every year to be protected. It is especially important for people at high risk of serious flu complications to get vaccinated. These people include:

  • Young children
  • Pregnant women
  • People who are 65 years and older
  • People with chronic health conditions like asthma, diabetes, heart and lung disease

When should I get the vaccine?

Flu season runs from October through March. Getting a vaccine earlier in the flu season can provide longer protection against the virus; however, vaccines are available all season. Adults and older children will only need one dose of vaccine to be protected; some children under 9 will need two doses. Check with your doctor to make sure.  

Can I get the flu from the flu vaccine?

It is not true that the flu vaccine can give you the flu but you should keep in mind that it takes two weeks after getting vaccinated to be fully protected against the flu.  Be sure to take other precautions against getting the flu during this time.  

What should I do if I get the flu?

  • Drink plenty of fluids
  • Stay home and avoid contact with others to prevent spreading the flu
  • Acetaminophen (Tylenol®) or ibuprofen (Motrin®, Nuprin® or Advil®) can be used to help relieve a fever. Follow package directions or talk to a healthcare provider to determine how much you or your family member can take
  • Do not give aspirin to children due to the risk of Reye's Syndrome, a rare but serious illness
  • Decongestants may help relieve a stuffy nose or sinus pressure in adults and older children
  • Your healthcare provider can prescribe antiviral medicines if you are at high risk of developing complications 

I am taking care of someone with the flu. How should I protect myself?
If you are caring for someone with the flu:

  • Wash your hands often
  • Ask those who are coughing or sneezing to cover their nose and mouth with a tissue
  • Avoid close contact with those who are sick (people with flu can spread it to others up to about 6 feet away) as much as possible.
  • Avoid touching your eyes, nose or mouth before washing your hands because germs are often spread this way
  • Clean surfaces touched by the ill person with a household cleaner
In addition, make sure the ill person is drinking enough fluids to prevent fluid loss (dehydration).

Where can I get the flu vaccine?

Contact your health care provider to get the flu vaccine. If you need to find a healthcare provider, contact the Mayor's Health Line at 617-534-5050. You can also get the flu vaccine at some local pharmacies.

Boston Public Health Commission
1010 Massachusetts Ave, 6th Floor, Boston, MA 02118.
Phone:(617) 534-5395 Email: