Before we begin: Stomach flu (gastroenteritis) is an inflammation of the intestines that causes diarrhea, pain, vomiting or fever. Learn what you can do to prevent it.
This tutorial walks you through everything you need to know about gastroenteritis. We explain it in plain language, step by step, so whether you are a student, a patient, or simply curious, you will come away with a solid understanding.
We cover what it is, why it matters, how it is diagnosed, and what you can do about it. Key facts are called out along the way.
What is 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.
What causes gastroenteritis? 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.
What are the symptoms of gastroenteritis? 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
For infants and children, they include:
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
How is gastroenteritis diagnosed? 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
What are the treatments for gastroenteritis? 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.
Can gastroenteritis be prevented? 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.
NIH: National Institute of Diabetes and Digestive and Kidney Diseases
Also known as: Stomach flu.
Related topics: Stomach Flu.
Categories: Digestive System, Infections.
Source: National Institutes of Health — National Institute of Diabetes and Digestive and Kidney Diseases.
Key Takeaways
Understanding gastroenteritis is an important part of taking charge of your health. Here is what to remember:
- Know the signs — Recognizing early symptoms can lead to earlier diagnosis and better outcomes.
- Talk to your provider — If you have concerns or a family history of this condition, bring it up at your next checkup.
- Stay informed — Medical knowledge evolves. Keep learning and asking questions.
- You are not alone — Many people deal with this condition. Support groups and educational resources can help.