Flu Basics

Influenza - Topic Overview

What is influenza (flu)?

Influenza (flu) is a viral infection. People often use the term "flu" to describe any kind of mild illness, such as a cold or a stomach virus, that has symptoms like the flu. But the real flu is different. Flu symptoms are usually worse than a cold and last longer. The flu usually does not cause vomiting or diarrhea.

Most flu outbreaks happen in late fall and winter.

What causes the flu?

The flu is caused by influenza viruses A and B. There are different strains, or types, of the flu virus every year.

What are the symptoms?

The flu causes a fever, body aches, a headache, a dry cough, and a sore or dry throat. You will probably feel tired and less hungry than usual. The symptoms usually are the worst for the first 3 or 4 days. But it can take 1 to 2 weeks to get completely better.

It usually takes 1 to 4 days to get symptoms of the flu after you have been around someone who has the virus.

Most people get better without problems. But sometimes the flu can lead to a bacterial infection, such as an ear infection, a sinus infection, or bronchitis. In rare cases, the flu may cause a more serious problem, such as pneumonia.

Certain people are at higher risk of problems from the flu. They include young children, pregnant women, older adults, and people with long-term illnesses or with impaired immune systems that make it hard to fight infection.

How is the flu diagnosed?

Your doctor will ask you about your symptoms and examine you. This usually gives the doctor enough information to find out if you have the flu, especially if many cases of a similar illness have occurred in the area and the local health department reports a flu outbreak.

In some cases, the doctor may do a blood test or take a sample of fluid from your nose or throat to find out what type of flu virus you have.

How is it treated?

Most people can treat flu symptoms at home. Home treatment includes resting, drinking plenty of fluids, and taking medicine to lower your fever.

If you think you have the flu, your doctor may be able to give you medicine that can make the symptoms milder. But you need to start taking it within 2 days of your first symptoms.

Can the flu be prevented?

You can help prevent the flu by getting the flu vaccine every year. The best time to get the vaccine is in October or November, just before the start of flu season. You can get the vaccine as a shot or in a spray that you breathe in through your nose.

Influenza - Home Treatment

If you have influenza, you can expect the illness to go away on its own in about 7 to 10 days. In the meantime, you can take steps to feel better:

• Get extra rest. Bed rest can help you feel better. It will also help you avoid spreading the virus to others.
• Drink plenty of fluids to replace those lost from fever. Fluids also ease a scratchy throat and keep nasal mucus thin. Hot tea with lemon, water, fruit juice, and soup are all good choices.
• If fever is uncomfortable, take acetaminophen or ibuprofen to lower it. You may also sponge your body with lukewarm water to reduce fever. Do not use cold water or ice. Lowering the fever will not make your symptoms go away faster, but it may make you more comfortable.
• To relieve body aches and headache, take acetaminophen or ibuprofen.
• Try a decongestant or nasal spray if your main symptom is a stuffy nose. Look for a single-ingredient decongestant that contains phenylephrine. If nasal drainage is thick, a decongestant that contains guaifenesin may help keep it thin and draining. Do not use medicated nasal sprays or drops more often than directed, and don't use them for longer than 3 days.
• To help clear a stuffy nose, breathe moist air from a hot shower or from a sink filled with hot water.
• Avoid antihistamines. They do not treat flu symptoms and may make nasal drainage thicker.
• If the skin around your nose and lips becomes sore from repeated rubbing with tissues, apply a bit of petroleum jelly to the area. Using disposable tissues that contain lotion also may help.
• Use cough drops or plain, hard candy to help ease coughing.
• Take a nonprescription cough medicine that contains dextromethorphan if you develop a dry, hacking cough. Some products contain a high percentage of alcohol. Use them with caution. Do not give cough and cold medicines to a child younger than 2 unless your child’s doctor has told you to. If your child’s doctor tells you to give a medicine, be sure to follow what he or she tells you to do.
• Elevate your head at night with an extra pillow if coughing keeps you awake.
• Avoid smoking and breathing secondhand smoke. This is good advice any time, but it is especially important when you have a respiratory infection like a cold or the flu.

Call your doctor if:

• Your symptoms improve but then seem to get worse again.
• You develop symptoms of a bacterial infection, such as a new or worse cough that produces yellow, green, rust-colored, or bloody mucus; persistent fever, ear pain, sore throat, sinus pain, or productive cough; or nasal drainage that changes from clear to colored after 7 to 10 days.