What is influenza?

Influenza (also called the flu) is a viral respiratory infection usually causing acute fever, body aches, cough, and fatigue.

The influenza virus may cause more severe symptoms than the common cold.  The elderly, young children, people whose immune systems are impaired, and people who have chronic medical problems are more susceptible to pneumonia and dehydration.

How does it occur?

A national epidemic of flu is common every year between November and March.  The influenza virus can infect you when you are exposed to an infected person’s upper respiratory fluids/droplets containing virus particles either released into the air by coughing or sneezing or after someone coughs into their hands and touches a surface, such as a door handle, contaminating it.

What are the symptoms?

Influenza tends to start suddenly over an hour with the usual first symptoms including:

  • Fever (often 101 to 103 degrees F or 38 to 40 C)/Chills/Sweating
  • Fatigue
  • Muscle aches/Headache
  • Runny nose/Cough/Sore throat
  • sometimes nausea/vomiting

These acute symptoms usually last 3 to 5 days with gradual improvement starting after the first 48 hours or so.


Infection with the flu virus may lead to other infections of ears, sinuses, bronchitis and pneumonia, or dehydration from unrelenting vomiting. Pneumonia can be caused by the influenza virus itself or by bacteria invading the virus-damaged lung tissues.

Another serious complication of flu related to the use of aspirin during influenza illness is Reye’s syndrome, which usually occurs in children and adolescents and rarely occurs in adults. Reye’s syndrome is not well understood but it involves failure of the liver and brain swelling, which together can lead to coma and sometimes death. For this reason it is best to AVOID aspirin use when you have the flu.

How is flu diagnosed?

Diagnosis can be made by nasal swab or by your symptoms and physical exam, which also may rule out other types of infection, such as strep throat and sinusitis.


  • It is very important to drink up to or more than 2 to 2.5 liters of liquids daily—water, juice, and non-caffeinated beverages are best. When you have high fever your body needs much more liquid, and increasing fluids also helps your body clear mucous.
  • Use nonprescription medicines to lower fever such as acetaminophen, ibuprofen or naproxen (Remember DO NOT use aspirin if you have flu, to prevent Reye’s syndrome). Fever, part of the immune system’s reaction to infection, may have benefit. However, letting the fever run its course can be dangerous in children and the elderly, and most healthy adults feel much better if the fever is decreased even 1 or 2 degrees.
  • Decongestants may help for congested nasal and sinus passages and may prevent bacterial ear or sinus infections.
  • Cough suppressants may be used safely for a cough, allowing you to rest.
  • Antihistamines can be helpful if a runny nose is making it hard for you to sleep well, however, they have a drying effect and may cause mucus to become thick and dry.
  • Antiviral medicines available by prescription are useful in the first 48 hours of symptoms of infection to lessen the illness by about 24 hours and improve symptoms; the antiviral medicines may be used to prevent flu if there are household contacts with known influenza. Examples of these drugs are amantadine (Symmetrel), rimantadine (Flumadine), zanamivir (Relenza), or oseltamivir (Tamiflu).

What can I do to prevent influenza?

The best way to prevent influenza is to get a flu shot every October. Flu shots are about 60-70% effective in preventing influenza. Very few people have side effects, such as mild flu-like symptoms in the first 24 hours after getting the flu vaccination. Do not get a flu shot if you are allergic to eggs as eggs are used in the vaccine-making process.

If the flu epidemic has begun and you have not been immunized but want some protection, you should get the flu vaccination as soon as possible.

The simplest method of avoiding the spread of flu infection is frequent hand washing. If you are sick stay home to avoid spreading infection and rest. Coughing should be done into the bend of your elbow and not into your hands.

*For further information see the Center for Disease Control web site: