Definition and Overview

Gastroenteritis (stomach flu) is a common illness that causes vomiting and diarrhoea. It usually occurs due to infections by viruses that inflame the lining of the intestines. Fungi, parasites, and bacteria can also cause it.

Gastroenteritis is one of the most common causes of hospitalisation in many countries around the world. In the United States, it affects about 180 million people and results in 5,000 deaths each year.

In otherwise healthy individuals, the illness usually resolves without treatment within two weeks. However, it can be very serious in people with a weak immune system. These include babies, the elderly, and those with certain diseases, such as AIDS or HIV.

A person can suffer from stomach flu by eating contaminated or improperly prepared food, sharing utensils with an infected individual, and drinking contaminated water. However, it can be prevented with frequent hand washing, getting vaccinated for rotavirus, and avoiding close contact with anyone who has it.

Patients have a high risk of dehydration because they commonly suffer from diarrhoea and vomiting at the same time. Thus, their treatment focuses on replacing the fluid they’ve lost as soon as possible (oral rehydration therapy). Intravenous fluids may become necessary in more serious cases.

Causes of Condition

Several viruses, bacteria, parasites, and fungi can cause this illness. The most common are rotavirus (in children) and norovirus (in adults). It can also be caused by certain bacteria, such as Escherichia coli (E. coli) and Campylobacter. The risk of infection is higher in the elderly and very young children because of their weak immune system.

The illness can easily cause localised epidemic because it is highly contagious. A child with stomach flu can infect a whole classroom in a matter of hours. This is the reason why doctors prefer that gastroenteritis be treated at home as much as possible.

Gastroenteritis can also occur due to non-infectious causes, such as:

  • Certain medications, especially nonsteroidal anti-inflammatory drugs (NSAIDs)

  • Lactose, for those who are lactose intolerant

  • Gluten, for those with celiac disease

  • Crohn’s disease

Key Symptoms

The key symptoms of gastroenteritis are vomiting and watery diarrhoea, which often lead to dehydration. A severely dehydrated person has a very dry mouth and skin. Other symptoms include nausea, stomach pain, cramping, headache, and fever.

Dehydration can quickly develop into more serious health problems. This is especially true for very young children because of their underdeveloped immune system. It is important that they are given fluids right away. This applies even before they are diagnosed with gastroenteritis. Sick children must be kept from school until all their symptoms have resolved.

The symptoms of gastroenteritis can also be caused by a number of medical conditions. These must be ruled out before treatment is provided. These diseases include:

Who to See and Types of Treatments Available

Diagnostic tests are usually not needed to confirm gastroenteritis. Most doctors are able to make a diagnosis by simply assessing the patient’s symptoms. Determining the cause of the illness is also usually not needed. This is because treatment remains the same regardless if it is due to bacteria or viruses.

However, stool cultures are needed in certain circumstances. An example is when blood is found in the stool. It is also used if the doctor suspects food poisoning or if the person has recently travelled to a developing country.

Gastroenteritis is rarely serious. Often, it resolves on its own without treatment. However, doctors usually prescribe medications and supplements for symptoms relief. These include anti-vomiting medications and oral rehydration solutions.

In case of severe dehydration, intravenous fluid therapy in the hospital may be needed. A nasogastric tube can also be used in young patients.

Gastroenteritis in children can be prevented with the rotavirus vaccine. This is proven effective in reducing severe disease especially among infants. Many countries around the world have seen a huge drop of rates of the disease following their national immunisation programme.


  • Tate JE, Burton AH, Boschi-Pinto C, Steele AD, Duque J, Parashar UD (February 2012). “2008 estimate of worldwide rotavirus-associated mortality in children younger than 5 years before the introduction of universal rotavirus vaccination programmes: a systematic review and meta-analysis”.

  • Zollner-Schwetz, I; Krause, R (August 2015). “Therapy of acute gastroenteritis: role of antibiotics.”. Clinical Microbiology and Infection. 21 (8): 744–9.

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