Flu (Influenza)

What is flu?

Flu (also called influenza) is a viral infection of your air passages that is much like a cold. Unlike most colds, however, the flu often causes fever, muscle aches, and dizziness as well as cold symptoms.

Infection with the flu virus sometimes leads to other infections, such as ear, sinus, and chest infections. Pneumonia can also occur as a result of the flu. It can be caused by the flu virus itself or by bacteria infecting lung tissues that have been damaged by the virus. Older adults; people whose immune systems are weak; and people with chronic medical problems, such as heart or lung disease or diabetes, are particularly at risk for more severe symptoms or problems. This is why it is important to try to prevent flu by getting flu shots every year.

What is the cause?

Flu is caused by a virus. When you are infected, the virus is in your mucus and saliva and can spread to others when you cough or sneeze. People can also get the flu if they touch something with the flu virus on it (like cups, doorknobs, and hands) and then touch their mouth, nose, or eyes.

Outbreaks of flu occur every year, usually in late fall and winter.

What are the symptoms?

Flu tends to start suddenly. You may feel fine one hour and have a high fever the next.

The usual first symptoms are:

• chills and fever (often 101 to 103°F, or 38 to 39.4°C)
• sweating
• body aches
• headache

Symptoms soon to follow may include:

• runny or stuffy nose
• cough
• sore throat
• tiredness

Flu symptoms usually last 3 to 7 days. Often you will start getting better after the first 2 days or so.

How is it diagnosed?

Your healthcare provider will ask about your symptoms and may examine you.

There are lab tests for flu, but they are not always accurate. The diagnosis is usually just based on your symptoms. In most cases there is no need to do a test.

How is it treated?

Usually you can treat your symptoms at home.

• Get plenty of rest.
• Drink a lot of clear liquids. Water, broth, juice, electrolyte solutions, and noncaffeinated drinks are best. When you have a high fever, your body needs more liquid because you lose more water in your breath and from your skin. Having enough fluids also helps the mucus in your sinuses and lungs stay thin and easy to clear from the body. When the mucus is thin, it is less likely to cause a sinus or chest infection.
• Consider taking acetaminophen or ibuprofen to relieve headaches and muscle aches and to lower a fever.
  • Don’t give any medicine that contains aspirin or salicylates to a child or teen. This includes medicines like baby aspirin, some cold medicines, and Pepto-Bismol. Children and teens who have the flu and take aspirin are at risk for a serious illness called Reye's syndrome.
  • Nonsteroidal anti-inflammatory medicines (NSAIDs), such as ibuprofen, naproxen, and aspirin, may cause stomach bleeding and other problems. These risks increase with age. Read the label and take as directed. Unless recommended by your healthcare provider, do not take for more than 10 days for any reason.
• If your nose or sinuses get congested, a decongestant medicine may help you feel better. Taking a decongestant may help prevent ear or sinus infections.
• Take cough medicine to help control your cough.
• Antihistamine medicine can be helpful if a runny nose is making it hard for you to sleep. However, antihistamine has a very drying effect and may make the mucus in your nose, throat, and lungs thick and dry. Antihistamines can also cause confusion. Older adults should check with their healthcare provider before taking this type of medicine.

  Don’t give young children any cough and cold medicines unless your child’s healthcare provider has told you to.

There are medicines your healthcare provider can prescribe that can make flu symptoms less severe. They may also help you feel better more quickly. Examples of these drugs are zanamivir (Relenza) and oseltamivir (Tamiflu). These flu medicines are available as tablets or nasal sprays. They help only if you start taking them within the first 2 days of illness. Usually they are taken only a few days.

Be sure to call your healthcare provider if you have symptoms of the flu and:

• You have heart disease, asthma, chronic bronchitis, kidney disease, diabetes, or another chronic medical problem.
• Your immune system does not work normally (for example, because you are taking steroid medicine for a medical problem).
• Your symptoms get more severe, you have a painful cough, you are coughing up mucus, or you are having trouble breathing. These symptoms can be signs of pneumonia.

How can I help prevent flu?

The flu vaccine is the best way to help prevent the flu. If you do get the flu even though you had your annual shot, the vaccine helps keep you from getting really sick.

Flu viruses change each year and the flu vaccine is made to protect against the kinds (strains) of flu virus that experts believe will be infecting people during the next flu season. So the vaccine changes every year and you need to get a new flu shot each year. It is best to get the flu vaccine in October or November at the start of flu season. However, you can get the vaccine anytime during the flu season (October through April) if it is available.

Flu seasons can vary from region to region. If you are at high risk for infection and plan to travel to an area where you might be exposed to the flu, make sure you have an up-to-date flu shot before you go on your trip.

The flu vaccine can be given as a shot or as a nasal spray. The shot contains killed virus and is safe for all ages. The nasal spray contains a weakened, live virus and is given only to healthy children over 2 and healthy, nonpregnant adults under 50. Pregnant women, children under 2 years, and people with weakened immune systems, asthma, or some other medical conditions cannot take the nasal spray. If you are thinking about getting the nasal spray, ask your provider if it is recommended for you.

If a flu outbreak has begun and you have not had the flu vaccine and need some protection, your healthcare provider may prescribe medicine that can lower your chances of getting the flu during the outbreak. If you do get the flu, the medicine can make your symptoms less severe.

Other things you can do to help avoid getting the flu are:

• Wash your hands often with soap and water. Wash for 20 seconds (long enough to sing the whole “Happy Birthday” song) or use an alcohol-based hand cleaner.
• Avoid touching your eyes, nose, or mouth when you are out in public.
• Stay away from people who are sick. Stay at least 6 feet away if you can.
• Try to take good care of yourself: Get plenty of sleep, be physically active, manage your stress, drink plenty of fluids, and eat healthy food. Stop smoking.
• Keep surfaces clean--especially bedside tables, surfaces in the bathroom, and toys for children. Some viruses and bacteria can live 2 hours or more on surfaces like cafeteria tables, doorknobs, and desks. Wipe them down with a household disinfectant according to directions on the label.
• It is a good practice not to eat in or near where you do your work--for example, if you are a cashier, salesperson, or school secretary. Your hands or food might be contaminated with virus particles from customers or schoolchildren, depending on your place of work.

If you are sick, you can help protect others if you:

• Don’t go to work or school. Avoid contact with other people except to get medical care. If you must leave the house, think about wearing a face mask if you have one.
• Cover your nose and mouth with a tissue when you cough or sneeze. Throw the tissue in the trash after you use it, and then wash your hands. If you don’t have a tissue, cough or sneeze into your upper sleeve instead of your hands.
• Clean your hands often with soap and water or an alcohol-based hand rub, especially after using tissues or coughing or sneezing into your hands.