Health Topic

Gastroenteritis

Stomach flu (gastroenteritis) is an inflammation of the intestines that causes diarrhea, pain, vomiting or fever. Learn what you can do to prevent it.

Reviewed Reviewed by a registered pharmacistGeneral information

Also called: Stomach flu

Important: This page is general information, not medical advice. It does not recommend or prescribe any treatment. Always consult your doctor or pharmacist before starting, stopping or changing any medicine.

About Gastroenteritis

Gastroenteritis is an inflammation of the lining of the stomach and intestines. The main symptoms include vomiting and diarrhea. It is usually not serious in healthy people, but it can sometimes lead to dehydration or cause severe symptoms.

There can be many different causes of gastroenteritis:

  • Viruses
  • Bacteria
  • Parasites
  • Chemicals
  • Reactions to certain medicines and food

Viral gastroenteritis is the most common type. It can be caused by many different viruses, including noroviruses and rotaviruses. Some people call viral gastroenteritis the "stomach flu." But this name is not medically correct. It is not caused by flu viruses. The flu is a respiratory infection that affects your nose, throat and lungs.

When gastroenteritis is caused by consuming foods or drinks contaminated with viruses, bacteria, parasites, or chemicals, this is called food poisoning.

The viruses, bacteria, and parasites that cause gastroenteritis can also spread from person to person. You could be infected when you touch something that has the germs on it and then touch your eyes, mouth, or nose.

The symptoms of gastroenteritis include:

  • Diarrhea
  • Pain or cramping in your abdomen (belly)
  • Nausea
  • Vomiting
  • Sometimes fever

Gastroenteritis is usually not serious. But it can sometimes cause lead to dehydration or cause severe symptoms. Certain people are at higher risk for these problems. They include:

  • Pregnant women
  • Older adults
  • People with weakened immune systems or other serious health conditions
  • Infants
  • Babies who were born prematurely or have other health conditions

If you or a family member are at higher risk and have symptoms of gastroenteritis, contact a health care provider right away. Even if you are not at high risk, it is possible to become dehydrated or have more serious symptoms. There are some warning signs to watch for. It's important to contact a provider right away if you or your child have any of them:

  • For adults, they include: Change in mental state, such as irritability or lack of energy
  • Diarrhea lasting more than 2 days
  • High fever
  • Vomiting often
  • Six or more loose stools in a day
  • Severe pain in the abdomen (belly) or rectum
  • Stools that are black and tarry or contain blood or pus
  • Symptoms of dehydration, such as thirst, dry mouth, headache, dark-colored urine, and urinating less than normal
  • Change in the child's mental state, such as irritability or lack of energy
  • Diarrhea lasting more than a day
  • Any fever in infants
  • High fever in older children
  • Frequent loose stools
  • Vomiting often
  • Severe pain in the abdomen (belly) or rectum
  • Signs or symptoms of dehydration, such as thirst, dry mouth, urinating less than usual or no wet diapers for 3 hours or more, and no tears when crying
  • Stools that are black and tarry or contain blood or pus

To find out if you have gastroenteritis, your provider:

  • Will do a physical exam
  • Will ask about your symptoms
  • May do tests of your stool

Usually, people with gastroenteritis get better on their own, with rest and plenty of fluids and electrolytes. Your provider may suggest that you take a probiotic. Studies suggest that some probiotics may help shorten a case of diarrhea.

People with more severe symptoms may need medicines to control nausea or vomiting. Providers may also give other medicines for certain types of gastroenteritis, such as antibiotics for some bacterial types and antiparasitic medicines for some parasitic types.

Gastroenteritis cannot always be prevented. But proper hand washing, cleaning surfaces that may be infected with germs, and safe food preparation may help prevent some of the infections that can cause gastroenteritis. There are vaccines for infants to protect against rotavirus infections.

It sits within Digestive System and Infections.

The lead U.S. institute for this subject is the National Institute of Diabetes and Digestive and Kidney Diseases.

When to speak to someone. Reading about a topic cannot tell you whether it applies to you. Speak to a doctor or pharmacist if symptoms are severe, sudden, getting worse, or simply not going away — and seek emergency care immediately for chest pain, breathing difficulty, sudden weakness or confusion, or a serious allergic reaction.

Research on Gastroenteritis

5,718 studies areregistered for this condition on ClinicalTrials.gov, the U.S. National Library of Medicine's public registry. A selection is below — the links go straight to the registry entry, not to a summary of ours.

What a registered study does and does not mean. Registration means a study exists and has been declared publicly. It says nothing about whether the treatment being tested works, is safe, or is available to you. Many studies find no benefit — that is what research is for. Never seek out an experimental treatment on the strength of a registry entry alone.

Research currently under way

Research already completed

Study data from ClinicalTrials.gov, a service of the U.S. National Library of Medicine. Retrieved 2026-07-30. Registry entries are supplied by study sponsors and investigators; ClinicalTrials.gov does not verify their scientific validity. PocketsInfo is not affiliated with, and not endorsed by, the NLM or the NIH.

Where to read more

Rather than paraphrase, we point you to the primary sources. Every link below is to a government health agency, a national institute or a recognised medical body — grouped by what you are trying to find out.

Start Here

Diagnosis and Tests

Treatments and Therapies

Prevention and Risk Factors

Related Issues

Clinical Trials

Medical subject headings

Clinicians and researchers index this subject under Gastroenteritis. These are the terms to use when searching medical literature.

This page is built from the MedlinePlus health topic record for Gastroenteritis, a service of the U.S. National Library of Medicine (NLM), National Institutes of Health. Information is from MedlinePlus.gov. PocketsInfo is not affiliated with, and is not endorsed by, the NLM or the NIH. Retrieved 30 July 2026.