Enteritis is an inflammation of the small intestine caused by a bacterial or viral infection. The inflammation frequently also involves the stomach (gastritis) and large intestine (colitis).

Causes, incidence, and risk factors
Enteritis is usually caused by eating or drinking substances contaminated with bacteria or viruses. The organism settles in the small intestine and causes inflammation and swelling that can cause abdominal pain, cramping, diarrhea, fever, and dehydration.

The symptoms may begin soon after exposure, or there can be a delay of several days. Mild cases usually need no treatment. The diarrhea can cause rapid and extreme dehydration in babies.

Risk factors include recent family illness with intestinal symptoms, recent travel, or exposure to untreated or contaminated water. The incidence is 3 out of 10,000 people.

Types of enteritis include:

  • Food poisoning  
  • Salmonella enteritis  
  • Shigella enteritis  
  • Staph aureus food poisoning  
  • Campylobacter enteritis  
  • E. coli enteritis  
  • Bacterial gastroenteritis  
  • Radiation enteritis  
  • Crohn’s disease and regional enteritis


  • Diarrhea that is acute and severe  
  • Vomiting (rare)  
  • Loss of appetite  
  • Abdominal pain

Signs and tests
A stool culture may grow the infecting organism. A stool sample may reveal specific toxins. An upper endoscopy is sometimes necessary to aid diagnosis.

Symptoms usually resolve in 1 to 5 days without treatment.

Antidiarrheal medication may delay the elimination of the organism from the digestive tract, and therefore may not be recommended. Rehydration with electrolyte solutions may be necessary if dehydration from diarrhea occurs.

People with diarrhea (especially young children) who are unable to take oral fluids because of nausea may need medical attention and intravenous fluids.

People taking diuretics need to be cautious with diarrhea, and may need to stop taking the diuretic during the acute episode, as directed by the health care provider.

Expectations (prognosis)
The illness usually runs its course without treatment in a few days.


  • Dehydration  
  • Prolonged diarrhea

Calling your health care provider
Call for an appointment with your health care provider if diarrhea does not resolve in 3 to 4 days or blood in stools is noted. Call your health care provider if symptoms of dehydration develop, or if other new symptoms develop.


  • Always wash hands after using the toilet and before eating or preparing food or drink.  
  • Avoid drinking from unknown sources, such as outside wells and streams, without boiling the water first.  
  • Use only clean utensils for eating or handling foods, especially when handling eggs and poultry.  
  • Cook food completely and properly.  
  • Store food appropriately in coolers.


Johns Hopkins patient information

Last revised: December 8, 2012
by Armen E. Martirosyan, M.D.

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