Stomach Flu (Gastroenteritis )

  • Medical Author:
    Charles Patrick Davis, MD, PhD

    Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.

  • Medical Editor: John P. Cunha, DO, FACOEP
    John P. Cunha, DO, FACOEP

    John P. Cunha, DO, FACOEP

    John P. Cunha, DO, is a U.S. board-certified Emergency Medicine Physician. Dr. Cunha's educational background includes a BS in Biology from Rutgers, the State University of New Jersey, and a DO from the Kansas City University of Medicine and Biosciences in Kansas City, MO. He completed residency training in Emergency Medicine at Newark Beth Israel Medical Center in Newark, New Jersey.

What are the signs and symptoms of stomach flu (gastroenteritis)?

The signs and symptoms of stomach flu may vary depending upon the cause.

  • The primary symptom of viral gastroenteritis (stomach flu) is diarrhea (non-bloody).
  • Nausea, vomiting, and some abdominal cramping may accompany the diarrhea.
  • Mild fever (about 100 F or 37.77 C), chills, headache, and muscle aches along with feeling tired may occur in some individuals with viral gastroenteritis.
  • Vomiting is occasional.
  • Symptoms usually last about 2 to 5 days and then begin to resolve with viral gastroenteritis.
  • Bacterial gastroenteritis (stomach flu) shares many of the symptoms as viral stomach flu, but in some individuals, bacteria may cause bloody diarrhea (hemorrhagic gastroenteritis).

Symptoms may occur in some individuals with either viral or bacterial stomach flu. Symptoms also may be seen with other causes of stomach flu (drugs, food allergies, toxins), for example:

  • Abdominal pain
  • Weight loss
  • Muscle aches and pains
  • Headache
  • Eosinophilia (mainly in allergic gastroenteritis)
  • Electrolyte loss
  • Severe gastroenteritis means the person has signs of dehydration; this is a medical emergency.

What are the signs and symptoms of stomach flu (gastroenteritis) in children?

Children with gastroenteritis or stomach flu usually have diarrhea, but may have other symptoms, for example:

  • Diarrhea
  • Refusing to eat or drink or are very thirsty
  • Either increased or low or no urine output
  • Weight loss
  • Lethargy
  • Bloody diarrhea
  • Pinched skin that does not rapidly go back to normal is a sign of dehydration, along with decreased fluid intake.

How is the stomach flu (gastroenteritis) spread?

Most viral and bacterial causes of the stomach flu can be transfer to other people by direct and indirect contact, usually by the fecal - oral route.

  • Direct contact could involve an infant's hand touching feces-contaminated surfaces and then touching a sibling or relative; indirect contact would be like touching a door knob or railing on a cruise ship or in a dorm that is contaminated and the person touches the contaminated surface and transfers the agent by touching their mouth.
  • Another common way to get stomach flu is drinking or eating contaminated foods and liquids.

Who gets the stomach flu (gastroenteritis)?

Gastroenteritis (stomach flu) is a common, worldwide disease and almost everyone suffers from it a few times in their life because it is almost impossible to avoid contact with some of the viral and bacterial causes.

  • People living in crowded conditions (military, cruise ships, dorms) are at higher risk, as are people living in developing countries who often have a diet that contains contaminated food or water.
  • Infants, children, and some adults (elderly, immunosuppressed) are at higher risk because of immature or depressed immune systems and also because they can become dehydrated faster than older children and adults.
  • Some people taking antibiotics are at higher risk because the antibiotics depress the normal GI microbes and allow bacteria or viruses like Clostridium difficile to predominate and cause disease.
  • People who do not practice good hygiene and hand washing techniques are at higher risk, as are those who eat under cooked and/or unwashed foods or drink from potentially contaminated fluid sources (rivers, streams, unpasteurized milk, for example).

How long does the stomach flu (gastroenteritis) last?

Depending upon the cause of gastroenteritis, it may be considered acute or chronic.

  • Acute gastroenteritis (viral) lasts about 7 to 14 days, and is then usually self-cured.
  • Chronic gastroenteritis (for example, allergic gastroenteritis) may last for months or longer if not diagnosed and appropriately treated.

Is stomach flu (gastroenteritis) contagious?

  • The large majority of causes (viral and bacterial) of gastroenteritis are contagious, usually through food or water contamination. In addition, they can be transferred person-to-person.
  • Exposures to body fluids (for example, feces or droplets containing infectious agents) are common sources that transmit the disease to others (See transmission section).
  • A few causes of gastroenteritis are not contagious, for example, food allergies or the side effects of medications.

What causes stomach flu (gastroenteritis)?

Bacteria and viruses - infectious agents - (the most common cause) are the most frequent causes of gastroenteritis in the U.S. and worldwide. Infections cause diarrhea and other symptoms by causing inflammation of the gastrointestinal (GI) tissue. The infections increase the fluid content in the intestines and colon by changing the gastrointestinal tract's ability to absorb water and by increasing the speed of transit (motility) for things you ingest. This, in turn, causes diarrhea. Infectious agents may physically damage intestinal cells directly or indirectly with secreted toxins.

Medically Reviewed by a Doctor on 11/21/2016
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