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Causes of Gastroenteritis

Medically reviewed by Elfred Landas, MD · General Practitioner · Maxicare Primary Care Center

Written by Jan Alwyn Batara · Updated May 05, 2021

    Causes of Gastroenteritis

    Gastroenteritis is a common condition that most people have experienced at least once in their lives. While gastroenteritis is usually from an infection, there are also other possible causes of gastroenteritis. Here’s what you need to know.

    What is Gastroenteritis?

    Gastroenteritis is simply the inflammation of the GI tract. It is also sometimes known as the stomach flu, despite not being caused by the viruses that cause the flu.

    The stomach is usually the part of the GI tract that’s affected by gastroenteritis, though it’s not uncommon for the small and large intestines to also be affected. It is a fairly common condition, and millions of people worldwide experience gastroenteritis each year.

    The symptoms associated with gastroenteritis can vary depending on what’s causing inflammation, but here are some common symptoms:

  • Bloating
  • Loss of appetite
  • Stomach cramps
  • Pain in the abdomen
  • Nausea
  • Diarrhea
  • Bloody stools
  • Fatigue or tiredness
  • Acute Gastroenteritis With Moderate Dehydration: Should I Be Worried?

    What are the Causes of Gastroenteritis?

    Because gastroenteritis refers to the inflammation of the GI tract, a number of things can be responsible for it. Here is a breakdown of each of the possible causes of gastroenteritis:

    Viral infection

    The most common cause of gastroenteritis is a viral infection. The viruses that cause gastroenteritis are usually norovirus in adults and rotavirus in children.

    A person can get infected by eating contaminated food and/or water. Infection can also occur through contact with an infected person. For the most part, viral gastroenteritis is not a cause for concern, and people usually recover from it without serious complications.

    However, people with compromised immune systems, as well as newborns, are particularly vulnerable to viral gastroenteritis. This can be avoided by washing your hands often and making sure that the food you eat and any water or liquid you drink is safe.

    Bacterial infection

    The second most common cause of gastroenteritis is bacterial infection. The bacteria usually responsible for gastroenteritis are Salmonella, E. coli, and Campylobacter.

    People can get infected with these bacteria by drinking contaminated water, eating undercooked food such as eggs, chicken, and dairy, or swimming in contaminated water.

    Cases of mild bacterial gastroenteritis usually go away after a few days. Though, patients need to stay hydrated in order to avoid dehydration.

    More serious cases of bacterial gastroenteritis might require hospitalization and intravenous fluids and electrolytes. In some cases, antibiotics may be necessary to help fight off the infection.

    Bacterial gastroenteritis can be avoided by washing your hands often, making sure the water you drink is clean, and cooking your food thoroughly to kill off any bacteria.


    Parasites can also cause gastroenteritis, and the most common cause of this is Giardia. This parasite can be found in food, soil, or water that has been contaminated by stool from humans or animals. When a person has been infected with Giardia, this condition is known as giardiasis. The symptoms are the same as gastroenteritis, and can last anywhere from two to six weeks.

    The most common method of infection occurs when a person drinks Giardia-contaminated water.

    While giardiasis goes away on its own, it’s still a good idea to see a doctor if it lasts for more than a week. Treatment for giardiasis involves taking medication to kill off the parasite.

    The best way to avoid giardiasis would be to make sure your drinking water is clean and to wash your hands often.


    Certain types of medication, particularly antacids, antibiotics, cancer medication, and certain laxatives, can sometimes trigger gastroenteritis. When a person develops gastroenteritis this way, it is a case of drug-induced or drug-related gastroenteritis.

    The usual symptoms of gastroenteritis are present, such as diarrhea, nausea, vomiting, and abdominal pain.

    Treatment for drug-induced gastroenteritis usually includes stopping the medication and managing the symptoms of gastroenteritis. If the patient does not get better, then it would be best to visit the doctor for further treatment.

    Learn more about Gastroenteritis here. 


    Hello Health Group does not provide medical advice, diagnosis or treatment.

    Medically reviewed by

    Elfred Landas, MD

    General Practitioner · Maxicare Primary Care Center

    Written by Jan Alwyn Batara · Updated May 05, 2021

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