The Difference Between Seasonal Flu and Stomach Flu

People often confuse the seasonal flu and stomach flu. Though their names are similar, they are actually two completely different and unrelated illnesses. The flu is caused by the influenza virus and symptoms mostly involve the upper respiratory tract. The stomach flu, medically known as viral gastroenteritis, can be caused by a number of viruses and causes gastrointestinal problems, such as diarrhea and vomiting.

Influenza
  • Cough

  • Congestion

  • Body aches and pains

  • Fever

  • Exhaustion or fatigue


Viral Gastroenteritis
  • Vomiting

  • Diarrhea

  • Stomach pain and cramping

  • Occasionally fever

Influenza

When your doctor talks about the flu, they are referring to influenza, or the seasonal flu. This virus circulates and makes people sick during flu season each year, and 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.

Influenza comes on suddenly and will make you feel terrible. The symptoms may last anywhere from two to 10 days and make it difficult to comfortably carry out daily tasks.

The most common influenza symptoms include:

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

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 healthcare 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 the medication. 

Gastroenteritis

The stomach flu is a completely different virus from the seasonal flu. As such, it cannot be prevented by getting a flu vaccination.

The stomach flu is most often caused by norovirus, rotavirus, or a food-borne bacteria and is characterized by:

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

In general, if an adult is sick with gastrointestinal symptoms, it is not influenza but viral gastroenteritis. However, in children, vomiting and diarrhea may occur with influenza.

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. 

A Word From Verywell

Though commonly confused for one another, the flu and the stomach flu are different viruses and illnesses. If you suspect you have influenza, see your doctor immediately for testing and treatment. If you suspect the stomach flu, watch out for signs of dehydration and call your doctor if symptoms linger.

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Article Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Centers for Disease Control and Prevention. Leading Causes of Death. Updated March 17, 2017.

  2. Centers for Disease Control and Prevention. Flu Symptoms & Complications. Updated September 18, 2019.

  3. National Institute of Diabetes and Digestive and Kidney Diseases. Symptoms & Causes of Viral Gastroenteritis (“Stomach Flu”). Updated May 2018.