Table of ContentsView AllTable of ContentsSelf-Check/At-HomeLabs and TestsDifferential DiagnosesFrequently Asked QuestionsNext in Stomach Flu GuideTreating Gastroenteritis With Medication, Diet, and Self Care
Table of ContentsView All
View All
Table of Contents
Self-Check/At-Home
Labs and Tests
Differential Diagnoses
Frequently Asked Questions
Next in Stomach Flu Guide
The stomach flu is not related to theinfluenza virus (“the flu”), which is a contagious upper respiratory condition.
Verywell / Hilary Allison
If a trip to a doctor is made, a diagnosis is most often made based on the symptoms and medical history.No formal testing is usually done.
The exception to this would be if there’s a reason to believe that there’s another condition responsible, such as if the symptoms are severe or go on for more than a few days.
In most cases, a physician probably won’t order any particular tests to diagnose viral gastroenteritis.
There’s not any specific test that can be used to make a diagnosis of the stomach flu. Instead, a complete medical history and a physical exam will be done, which will likely be enough to make a presumptive diagnosis.
There is a test forrotavirus, a viral disease that also causes vomiting and diarrhea. It is more common in children.In a case where rotavirus may be suspected, a test might be done to diagnose that condition.
In some cases, if there is an outbreak of a viral disease such as in a hospital,testing might be done to find out which strain of the virus is causing it, but this is not common.
Medical History
A doctor will take a careful medical history to see if there is another reason why someone might have diarrhea and vomiting.Some of the questions a physician might ask about recent and past medical history include:
Physical Exam
A physical exam may also be done. Physical exams could include:
Digital Rectal Exam
Digital rectal examis used to check for blood or mucus in the rectum and to look for any problems around the anus.This exam can cause a bit of anxiety and embarrassment but it should be painless and the doctor will get it completed as quickly as possible.
There are a few different positions in which the patient might get into to prepare for the exam:
A physician will insert a gloved, lubricated finger into the anus to check for blood in the stool. Patients may feel pressure or discomfort but it should not cause any pain.This test might also be used to feel for any abnormalities such ashemorrhoidsor a mass.
If anything is found during this test it could mean that there’s more than the stomach flu causing symptoms.
Stool Test
Usually,stool testswon’t be used for diagnosing viral gastroenteritis. There may be situations, however, where a stool test is ordered.
It is a fairly simple test to complete, although many people do not turn in their stool sample out of embarrassment. If a physician orders this test, it’s important to get it done to see if there is anything present in the stool that might be causing symptoms.
The physician’s office will give instructions and a clean container for catching stool. When there is diarrhea, holding the container under the bottom during a bowel movement may be the easiest way to get a stool sample.
The sample will need to be sent to a lab and tested to see if there is anything in it that can cause an infection or inflammation.
Other Tests
It’s not common forblood testsor imaging tests to be done when the stomach flu is the presumed diagnosis. However, if another disease or condition is suspected, blood tests or imaging such as ultrasonography,computed tomography, ormagnetic resonance imagingmay be done to confirm or rule it out.
A list of conditions that might be the cause of the signs and symptoms a patient is having is called the differential diagnoses. In some cases, it might be suspected that there isanother condition causing the symptoms, and that would need to be ruled out.
This is especially true when there are symptoms likebloodormucus in the stool,black stool,severe abdominal pain, or a high fever.
Symptoms that go on for more than a few days or don’t seem to be improving may also be a reason to consider more testing for another cause.
Some of the diseases and conditions a physician might look for include:
In most cases, it’s enough to diagnose the stomach flu from a physical exam and a careful medical history. The majority of the time, people start to feel better in a few days and so they never see a doctor. When a doctor is consulted about the stomach flu, treatment is mostly supportive while the virus runs its course.
It depends on the virus. With some viruses, you can be contagious even when you don’t feel sick. For example, norovirus can be spread before you have symptoms or up to two weeks after you get better.
You may not feel like eating when you’re sick, but the most important thing is to make sure you’re drinking plenty of fluids. You can start with clear liquids like water and broth and add others like sports drinks as you feel up to it. You can eat your normal diet as soon as your appetite returns.
How Stomach Flu Is Treated
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18 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Cleveland Clinic.Gastroenteritis: management and treatment.National Institute of Diabetes and Digestive and Kidney Diseases.Definition & facts for viral gastroenteritis (“stomach flu”).The National Institute of Diabetes and Digestive and Kidney Diseases.Diagnosis of viral gastroenteritis (“stomach flu”).Johns Hopkins Medicine Health Library.Understanding viral gastroenteritis.MedlinePlus.Rotavirus antigen test.Centers for Disease Control and Prevention.Common settings of norovirus outbreaks.Cleveland Clinic.Gastroenteritis: diagnosis and tests.Harvard Medical School.Digital rectal exam.Boyce TG.Gastroenteritis. Merck Manual.Johns Hopkins Medicine Health Library.Celiac disease.MedlinePlus.Diabetic ketoacidosis.Struyvenberg MR, Martin CR, Freedman SD.Practical guide to exocrine pancreatic insufficiency - breaking the myths.BMC Med. 2017;15(1):29. doi:10.1186/s12916-017-0783-yNational Institute of Diabetes and Digestive and Kidney Diseases.Short bowel syndrome.Centers for Disease Control and Prevention.What is inflammatory bowel disease (IBD)?Weinberg GA.Urinary tract infection (UTI) in children. Merck Manual.International Foundation for Gastrointestinal Disorders.Volvulus.National Institute of Diabetes and Digestive and Kidney Diseases.Whipple disease.National Institute of Diabetes and Digestive and Kidney Diseases.Symptoms & causes of viral gastroenteritis (“stomach flu”).Additional ReadingRotavirus: vaccination. National Center for Immunization and Respiratory Diseases, Division of Viral Diseases. Centers for Disease Control and Prevention.Norovirus: Prevention. National Center for Immunization and Respiratory Diseases, Division of Viral Diseases. Centers for Disease Control and Prevention.Viral gastroenteritis (stomach flu). Mayo Clinic Staff. Mayo Clinic.Whipple’s disease. Mayo Clinic Staff. Mayo Clinic.Treatment of Viral Gastroenteritis (“Stomach Flu”). U.S. Department of Health and Human Services. National Institutes of Health.
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
Cleveland Clinic.Gastroenteritis: management and treatment.National Institute of Diabetes and Digestive and Kidney Diseases.Definition & facts for viral gastroenteritis (“stomach flu”).The National Institute of Diabetes and Digestive and Kidney Diseases.Diagnosis of viral gastroenteritis (“stomach flu”).Johns Hopkins Medicine Health Library.Understanding viral gastroenteritis.MedlinePlus.Rotavirus antigen test.Centers for Disease Control and Prevention.Common settings of norovirus outbreaks.Cleveland Clinic.Gastroenteritis: diagnosis and tests.Harvard Medical School.Digital rectal exam.Boyce TG.Gastroenteritis. Merck Manual.Johns Hopkins Medicine Health Library.Celiac disease.MedlinePlus.Diabetic ketoacidosis.Struyvenberg MR, Martin CR, Freedman SD.Practical guide to exocrine pancreatic insufficiency - breaking the myths.BMC Med. 2017;15(1):29. doi:10.1186/s12916-017-0783-yNational Institute of Diabetes and Digestive and Kidney Diseases.Short bowel syndrome.Centers for Disease Control and Prevention.What is inflammatory bowel disease (IBD)?Weinberg GA.Urinary tract infection (UTI) in children. Merck Manual.International Foundation for Gastrointestinal Disorders.Volvulus.National Institute of Diabetes and Digestive and Kidney Diseases.Whipple disease.National Institute of Diabetes and Digestive and Kidney Diseases.Symptoms & causes of viral gastroenteritis (“stomach flu”).
Cleveland Clinic.Gastroenteritis: management and treatment.
National Institute of Diabetes and Digestive and Kidney Diseases.Definition & facts for viral gastroenteritis (“stomach flu”).
The National Institute of Diabetes and Digestive and Kidney Diseases.Diagnosis of viral gastroenteritis (“stomach flu”).
Johns Hopkins Medicine Health Library.Understanding viral gastroenteritis.
MedlinePlus.Rotavirus antigen test.
Centers for Disease Control and Prevention.Common settings of norovirus outbreaks.
Cleveland Clinic.Gastroenteritis: diagnosis and tests.
Harvard Medical School.Digital rectal exam.
Boyce TG.Gastroenteritis. Merck Manual.
Johns Hopkins Medicine Health Library.Celiac disease.
MedlinePlus.Diabetic ketoacidosis.
Struyvenberg MR, Martin CR, Freedman SD.Practical guide to exocrine pancreatic insufficiency - breaking the myths.BMC Med. 2017;15(1):29. doi:10.1186/s12916-017-0783-y
National Institute of Diabetes and Digestive and Kidney Diseases.Short bowel syndrome.
Centers for Disease Control and Prevention.What is inflammatory bowel disease (IBD)?
Weinberg GA.Urinary tract infection (UTI) in children. Merck Manual.
International Foundation for Gastrointestinal Disorders.Volvulus.
National Institute of Diabetes and Digestive and Kidney Diseases.Whipple disease.
National Institute of Diabetes and Digestive and Kidney Diseases.Symptoms & causes of viral gastroenteritis (“stomach flu”).
Rotavirus: vaccination. National Center for Immunization and Respiratory Diseases, Division of Viral Diseases. Centers for Disease Control and Prevention.Norovirus: Prevention. National Center for Immunization and Respiratory Diseases, Division of Viral Diseases. Centers for Disease Control and Prevention.Viral gastroenteritis (stomach flu). Mayo Clinic Staff. Mayo Clinic.Whipple’s disease. Mayo Clinic Staff. Mayo Clinic.Treatment of Viral Gastroenteritis (“Stomach Flu”). U.S. Department of Health and Human Services. National Institutes of Health.
Rotavirus: vaccination. National Center for Immunization and Respiratory Diseases, Division of Viral Diseases. Centers for Disease Control and Prevention.
Norovirus: Prevention. National Center for Immunization and Respiratory Diseases, Division of Viral Diseases. Centers for Disease Control and Prevention.
Viral gastroenteritis (stomach flu). Mayo Clinic Staff. Mayo Clinic.
Whipple’s disease. Mayo Clinic Staff. Mayo Clinic.
Treatment of Viral Gastroenteritis (“Stomach Flu”). U.S. Department of Health and Human Services. National Institutes of Health.
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