The Difference Between Seasonal Flu and Stomach Flu

People often get confused about the differences between the flu, or influenza, and the stomach flu. These are actually two completely different, and unrelated, illnesses. The true flu is caused by the influenza virus and causes mostly upper respiratory problems. The "stomach flu" can be caused by a number of viruses and causes gastrointestinal problems, such as diarrhea and vomiting.

Influenza (the Flu)

When your doctor talks about the flu, he is referring to influenza, or the seasonal flu. This virus circulates and makes people sick during flu season each year. It can be a very serious illness. When combined with pneumonia, it is one of the top 10 causes of death in the United States. The most common symptoms include:

  • Cough
  • Congestion
  • Body aches and pains
  • Fever
  • Exhaustion or fatigue

Influenza comes on suddenly and will make you feel terrible. It is very difficult to continue on with your life when you have the flu. The symptoms may last anywhere from 2 to 10 days. Although most healthy people recover from the flu without any serious problems, some people may develop complications or secondary infections. If you have the flu, start feeling better for a few days and then develop worse symptoms with a higher fever, contact your health care provider. This is a classic sign that you have developed a secondary infection. You may need a different treatment depending on your diagnosis. 

If you think you might have the flu, especially if you are in a high risk group, contact your healthcare provider as soon as possible to see if you might benefit from antiviral medications. If taken within the first 48 hours of the start of your symptoms, they can lessen the severity and shorten the duration of your illness. Meaning you won't feel quite as bad for as long as you would have if you hadn't taken it. 

Gastroenteritis (Stomach Flu)

The "stomach flu" is a completely different virus from the seasonal flu. It is most often caused by norovirus, rotavirus or a food-borne bacteria and is characterized by:

  • Vomiting
  • Diarrhea
  • Stomach pain and cramping
  • Occasionally fever

People with influenza will sometimes have vomiting and diarrhea, but these symptoms are rare. Vomiting and diarrhea are more common in children with the flu.

Gastroenteritis, although it is miserable, is typically not as serious as influenza. You may need to seek medical attention if you are dehydrated. Vomiting usually lasts no longer than 24 hours. Diarrhea may continue for several days after that. If you are vomiting frequently and unable to keep fluids down, contact your healthcare provider. 

As you can see, there is a big difference between the flu and the "stomach flu". They are not caused by the same viruses and the symptoms are not really similar. 

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Article Sources

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  • "Gastroenteritis". MedlinePlus. 19 Feb 16. US National Library of Medicine. US Department of Health and Human Services. National Institutes of Health. 28 Feb 16. 
  • "Flu Symptoms & Severity". Seasonal Influenza (Flu) 16 Sep 15. US Centers for Disease Control and Prevention. Department of Health and Human Services. National Institutes of Health. 28 Feb 16.