Flu symptoms come on very quickly and can include sudden fever -- a temperature of 100 degrees Fahrenheit or higher. Other symptoms include aches, fatigue, dry, chesty cough, sore throat, headache, loss of appetite, diarrhea, and nausea. Dehydration occurs quickly when you have the stomach flu, so it is vital to consume enough clear liquids to stay hydrated. This helps your immune system defeat the virus.

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