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

Typical clinical features of influenza may include

• fever (usually 100 F-103 F in adults and often even higher in children),
• chills,
• respiratory symptoms such as
• cough (more often in adults),
• sore throat (more often in adults),
• runny or stuffy nose (especially in children),
• headache,
• muscle aches,
• fatigue, sometimes extreme.

Although nausea, vomiting, and diarrhea can sometimes accompany influenza infection, especially in children, gastrointestinal symptoms are rarely prominent. The term "stomach flu" is a misnomer that is sometimes used to describe gastrointestinal illnesses caused by other microorganisms. H1N1 infections, however, have caused more nausea, vomiting, and diarrhea than the conventional (seasonal) flu viruses.

Most people who get the flu recover completely in one to two weeks, but some people develop serious and potentially life-threatening medical complications, such as pneumonia. In an average year, influenza is associated with about 36,000 deaths nationwide and many more hospitalizations. Flu-related complications can occur at any age; however, the elderly and people with chronic health problems are much more likely to develop serious complications after the conventional influenza infections than are younger, healthier people. However, the H1N1 virus had developed a different pattern of infection. Unfortunately, the pattern of infection is similar to that of the 1918 "Spanish flu" pandemic in which young people (pregnant individuals, infants, teens, and adults through age 49) are the most susceptible populations worldwide. Analysis of the people who were likely to develop complications from the H1N1 infection showed that other groups of people were also susceptible, including American Indians, patients with COPD, and obese individuals.

Unfortunately, people may be contagious about 24-48 hours before symptoms appear and, for those people who spontaneously recover, they may shed contagious viruses for about a week.