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. webmd medical reference from healthwise this information is not intended to replace the advice of a doctor. healthwise disclaims any liability for the decisions you make based on this information. © 1995-2011 healthwise incorporated. healthwise healthwise for every health decision and the healthwise logo are trademarks of healthwise incorporated.
what is influenza (flu)?