Gastroenteritis (gas-tro-en-ter-I-tis) is a disease in which the lining of the stomach and intestines becomes inflamed, resulting in what is sometimes referred to as an upset stomach or stomach flu.

What Is Gastroenteritis?

Gastroenteritis is a general term for inflammation * of the gastrointestinal (GAS-tro-in-TES-ti-nal) tract, the part of the digestive system consisting of the stomach, small intestine, and large intestine. Loss of appetite, vomiting, cramps, nausea * , and diarrhea * are the most common symptoms of gastroenteritis. In the United States, gastroenteritis usually is a mild disease; it is also a common one, with one in every six Americans developing a case of stomach flu each year. In countries in which water supplies are dirty, sewage treatment is poor, or medical facilities are scarce, it sometimes leads to death.

What Causes Gastroenteritis?

There are many different causes of gastroenteritis. Viral infections are the most common cause in the United States. Certain bacteria and parasites that can get into food or water supplies also can lead to the disease. In addition, gastroenteritis can result from food allergies or sensitivities; side effects of certain medications; and alcohol or toxic (poisonous) substances.


Norovirus, sometimes called the winter vomiting bug, is the most common cause of acute gastroenteritis in the United States. Each year, it causes 19 to 21 million illnesses, and contributes to 56,000 to 71,000 hospitalizations and 570 to 800 deaths. Norovirus is also the most common cause of foodborne disease outbreaks in the United States.

The norovirus became the subject of a number of news articles after it was diagnosed in cruise ship travelers. Besides being transmitted on cruise ships, this virus is easily spread in restaurants and in places where people share close quarters, such as day care centers, nursing homes, and schools. Eighty percent of norovirus infections occur during the colder months, between November and April in the United States.

The most common symptoms of norovirus infection include:

There is no specific treatment for norovirus. Most people recover within one to three days. When diagnosed, people are urged to drink plenty of liquids to prevent dehydration.

How Is Gastroenteritis Treated?

Mild gastroenteritis usually lasts just two or three days. Often, the only treatment needed is rest and drinking lots of clear fluids. Gastroenteritis can be serious if vomiting and diarrhea cause dehydration (de-hy-DRAYshun), a condition that results when a person loses fluid and body salts faster than they can be replaced by drinking. If a person becomes dehydrated, hospitalization may be needed to deliver intravenous (in-tra-VEEnus) fluid replacement therapy. Intravenous (IV) therapy replaces lost fluid by dripping liquids and salts directly into the bloodstream through a small needle inserted into a vein.

How Can Gastroenteritis Be Prevented?

Washing the hands thoroughly after using the toilet, before handling food, and before eating are important ways to prevent infectious gastroenteritis. Preparing and storing food properly are important. For people who plan to visit developing countries, vaccines * are available against some of the diseases that cause gastroenteritis.

See also Diarrhea • Food Poisoning • Travel-Related Infections: Overview • Viral Infections


Books and Articles

Lindsay, Lisa, Joanne Wolter, Ilse De Coster, Pierre Van Damme, and Thomas Verstraeten. “A Decade of Norovirus Disease Risk Among Older Adults in Upper-Middle and High Income Countries: A Systematic Review.” BMC Infectious Diseases 15 (2015): 425.


Centers for Disease Control and Prevention. “Norovirus.” (accessed March 16, 2016).

Merck Manual, Consumer Version. “Overview of Gastroenteritis.” (accessed July 16, 2016).


Centers for Disease Control and Prevention. 1600 Clifton Rd., Atlanta, GA 30329-4027. Toll-free: 800-232-4636. Website: (accessed March 16, 2016).

National Library of Medicine. 8600 Rockville Pike, Bethesda, MD 20894. Toll-free: 888-346-3656. Website: (accessed March 16, 2016).

* inflammation (in-fla-MAY-shun) is the body's reaction to irritation, infection, or injury that often involves swelling, pain, redness, and warmth.

* nausea (NAW-zha) refers to a feeling of being sick to one's stomach or needing to vomit.

* diarrhea (di-ah-RE-a) refers to frequent watery stools (bowel movements).

* vaccines (vak-SEENS) are preparations of killed or weakened germs, or a part of a germ or product it produces, given to prevent or lessen the severity of disease if a person is exposed to the germ itself.

Disclaimer:   This information is not a tool for self-diagnosis or a substitute for professional care.

(MLA 8th Edition)