Flu vs. Stomach Flu: What Is the Difference?

The seasonal flu and stomach flu are completely different 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.

This article covers the differences between the seasonal flu and the stomach flu. It discusses symptoms, treatment, and when to call a healthcare provider.

Influenza
  • Cough

  • Congestion

  • Body aches and pains

  • Fever

  • Exhaustion or fatigue


Viral Gastroenteritis
  • Vomiting

  • Diarrhea

  • Stomach pain and cramping

  • Occasionally fever

Influenza

When your healthcare provider 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.

Symptoms

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 or feeling feverish or chills
  • Exhaustion or fatigue
  • Sore throat
  • Runny or stuffy nose
  • Headaches
  • Fatigue (tiredness)
  • Vomiting and diarrhea (more common in children than adults)

Although most symptoms of the flu go away within four to seven days, the cough and tiredness can last for weeks. Most healthy people recover without any serious problems, but some people may develop complications or secondary infections.

potential flu complications
 Verywell / Brianna Gilmartin

Treatment

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. This means 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 foodborne bacteria.

Symptoms

Stomach flu symptoms often include:

  • 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. Stomach flu usually lasts for just a few days, but depends on what is causing it. Norovirus is the most common cause and symptoms typically last one to two days.

Treatment

Gastroenteritis, although it is miserable, is typically not as serious as influenza and usually resolves on its own. Vomiting usually lasts no longer than 24 hours; diarrhea may continue for several days after that.

When To Call a Healthcare Provider

Reasons to call a healthcare provider differ for the flu and stomach flu.

Influenza

If you think you have the flu, call your healthcare provider right away, since antiviral medications will only be prescribed within 48 hours of symptoms.

You should contact your healthcare provider right away if you experience:

  • Difficulty breathing
  • Shortness of breath
  • Persistent chest or abdominal pain
  • Dizziness, confusion, or difficulty waking
  • Seizures
  • Severe muscle pain or weakness
  • Worsening cough or fever

If you start feeling better for a few days and then develop worsening symptoms, this is a classic sign that you have developed a secondary infection. You may need different treatments depending on your diagnosis.

Gastroenteritis

With the stomach flu, adults should see a healthcare provider right away with any of these symptoms:

  • Irritability or lack of energy
  • Diarrhea lasting more than two days
  • High fever (over 104 F)
  • Vomiting often
  • Six or more loose stools in a day
  • Severe stomach or rectum pain
  • Stools that are black and tarry or contain blood or pus
  • Symptoms of dehydration

If you are vomiting frequently and unable to keep fluids down, contact your healthcare provider. 

Summary

Though commonly confused with one another, the flu and the stomach flu are different viruses and illnesses. Flu symptoms typically last longer than stomach flu symptoms. The flu mostly affects the upper respiratory tract, while the stomach flu causes gastrointestinal problems.

If you suspect you have influenza, see your practitioner immediately for testing and treatment. If you suspect the stomach flu, watch out for signs of dehydration and call your healthcare provider if symptoms are severe or linger.

5 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.

  2. Centers for Disease Control and Prevention. Flu Symptoms & Complications.

  3. Penn Medicine. Flu (Influenza).

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

  5. Centers for Disease Control and Prevention. Norovirus illness: key facts.

By Kristina Herndon, RN
Kristina Herndon, BSN, RN, CPN, has been working in healthcare since 2002. She specializes in pediatrics and disease and infection prevention.