1. Foods to Eat When You Have the Flu Slideshow
2. Natural Cold and Flu Remedies Pictures
3. Finding Relief for Your Cough Slideshow

Medical Author:

Charles Patrick Davis, MD, PhD

Charles Patrick Davis, MD, PhD

Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.

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Medical Editor:

Melissa Conrad Stöppler, MD

Melissa Conrad Stöppler, MD

Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

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In this Article

• Flu (influenza, conventional, and H1N1) facts
• What is influenza?
• What are the causes of the flu?
• What are flu symptoms in adults and in children?
• How is the flu diagnosed?
• What is the key to flu prevention?
• Are there any flu shot or nasal spray vaccine side effects in adults or in children?
• Why should the influenza vaccine be taken every year?
• What are some treatments an individual can do at home for the flu?
• When should a person go to the emergency department for the flu?
• Who should receive the flu vaccine, and who has the highest risk factors? When should someone get the flu shot?
• What is the prognosis (outlook) and complications for patients who get the flu?
• What is the bird (avian) flu?
• Do antiviral agents protect people from the flu?
• Is it safe to get a flu shot that contains thimerosal?
• Where can I find additional information about the flu?
• Slideshow: Foods to Eat When You Have the Flu
• Slideshow: Natural Cold & Flu Remedies
• Slideshow: Finding Relief for Your Cough
• Patient Comments: Flu (Influenza) - Symptoms
• Patient Comments: Flu (Influenza) - Side effects
• Influenza Index

In general, the majority (about 90%-95%) of people who get the disease feel terrible (see symptoms) but recover with no problems. People with suppressed immune systems historically have worse outcomes than uncompromised individuals; current data suggest that pregnant individuals, children under 2 years of age, young adults, and individuals with any immune compromise or debilitation are likely to have a worse prognosis. In most outbreaks, epidemics and pandemics, the mortality rates are highest in the older population (usually above 50 years old). Complications of any flu virus infection, although relatively rare, may resemble severe viral pneumonia or the SARS (severe acute respiratory syndrome caused by a coronavirus strain) outbreak in 2002-2003 in which the disease spread to about 10 countries with over 7,000 cases, over 700 deaths, and had a 10% mortality rate.

At the beginning of the recent 2009 H1N1 pandemic, the numbers of people with flu-like illness were higher than usual and the illness initially affected a much younger population than the conventional flu. As the pandemic progressed, more young children became infected than usual, but the mortality statistics became more similar to those of the conventional flu mortality with an older population (especially ages 50-64) having the highest death rate. The best news about the H1N1 swine flu is that the majority of people worldwide who has caught the H1N1flu recovered without medical treatment and had an excellent prognosis, but this is not always the situation as demonstrated by the 1918 flu pandemic.

The bird flu, also known as avian influenza and H5N1, is an infection caused by avian influenza A. This virus is not the one that causes SARS, an acute respiratory syndrome caused by a coronavirus. Bird flu can infect many bird species, including domesticated birds such as chickens. In most cases, the disease is mild; however, some subtypes can be pathogenic and rapidly kill birds within 48 hours. Rarely, humans can be infected by these bird viruses. People who get infected with bird flu usually have direct contact with the infected birds or their waste products. Depending on the viral type, the infections can range from mild influenza to severe respiratory problems or death. Human infection with bird flu is rare but frequently fatal. More than half of those people infected (over 340 infected people) have died (current estimates of the mortality [death] rates in humans is about 60%). Fortunately, this virus does not seem to be easily passed from person to person. The major concern among scientists and physicians about bird flu is that it will change (mutate) its viral RNA enough to be easily transferred among people and produce a pandemic similar to the one of 1918. There have been several isolated instances where a person has been reported to get avian flu in 2010; the virus was detected in South Korea (three human cases) resulting in a quarantine of two farms, and in 2012, over 10,000 turkeys died in a H5N1 outbreak with no human infections recorded. Recent research suggests that some people may have had exposure to H5N1 in their past but had either mild or no symptoms.

In addition, researchers, in an effort to understand what makes an animal or bird flu become easily transmissible to humans, developed a bird flu strain that is likely easily transmitted from person to person. Although it exists only in research labs, there is controversy about both the synthesis and the scientific publication of how this potentially highly pathogenic strain was created.

Vaccination is the primary method for control of influenza; however, antiviral agents have a role in the prevention and treatment of mainly influenza type A infection. Regardless, antiviral agents should not be considered as a substitute or alternative for vaccination.

As of Dec. 15, 2010, the CDC published the following concerning antiviral medications:

Antiviral medications with activity against influenza viruses are an important adjunct to influenza vaccine in the control of influenza.

• Influenza antiviral prescription drugs can be used to treat influenza or to prevent influenza.
• Oseltamivir and zanamivir are chemically related antiviral medications known as neuraminidase inhibitors that have activity against both influenza A and B viruses.

The following is the CDC recommended dosage for antiviral medications for the treatment of influenza (flu) for the 2012-2013 season:

• Antiviral treatment is recommended as soon as possible for patients with confirmed or suspected influenza who have severe, complicated, or progressive illness, or who are hospitalized.
• Antiviral treatment is recommended as soon as possible for outpatients with confirmed or suspected influenza who are at higher risk for influenza complications based on their age and/or medical conditions; clinical judgment should be an important component of outpatient treatment decisions.
• Antiviral medications currently recommended include oseltamivir and zanamivir, based upon recent viral surveillance and resistance data indicating that >99% of currently circulating influenza virus strains are sensitive to these medications. Amantadine (Symmetrel) and rimantadine (Flumadine) should not be used because of high levels of resistance to these drugs among circulating influenza A viruses.
• Oseltamivir should be used to provide treatment or chemoprophylaxis (prevention of the flu after exposure to the virus) for infants younger than 1 year of age when indicated.
• Antiviral treatment can be considered for any previously healthy non-high-risk symptomatic outpatient with confirmed or suspected influenza who is not in the recommended groups, based upon clinical judgment, if treatment can be initiated within 48 hours of illness onset.