What Is Enteritis? Everything You Need to Know

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Inflammation of the small intestine is called enteritis. Inflammation (redness and swelling) might be caused by infection, certain medications, radiation treatments, or chronic illnesses such as Crohn’s disease or celiac disease. Symptoms can include pain, diarrhea, vomiting, and blood in the stool.

A person holding a model of human intestines in front of body on white background.

Ben-Schonewille / iStock / Getty Images Plus


Enteritis can be caused by a range of conditions or medications that affect the small intestine. In some cases, enteritis might be caused by eating or drinking something contaminated by bacteria or viruses. Radiation treatment for cancer can also lead to inflammation in the digestive system.

Some causes of enteritis are:

  • Bacterial infection
  • Celiac disease (an autoimmune disease in which your white blood cells attack your intestinal lining after exposure to gluten)
  • Crohn’s disease (an inflammatory bowel disease)
  • Nonsteroidal anti-inflammatory drugs (NSAIDs, including the ibuprofens Aleve and Motrin and the naproxen Aleve)
  • Radiation treatment
  • Viral infection
  • Whipple disease (a rare bacterial infection that leads to a difficulty breaking down fats in the digestive tract)


The type of enteritis will depend on the cause of the inflammation. The more common reasons include food poisoning and radiation enteritis.

Infectious Enteritis (Food Poisoning)

Food poisoning that occurs after eating or drinking food that’s been contaminated with a virus or a bacterium can cause enteritis.


There are an estimated 48 million cases of food poisoning in the United States every year.

Food could be contaminated if it isn’t cooked or stored properly. Food poisoning can also occur when food comes into contact with water or utensils that are not washed properly after being contaminated with a virus or a bacterium.

Contamination can also occur if food is prepared by someone who doesn’t wash their hands properly after using the bathroom or before starting to cook.

Radiation Enteritis

Radiation therapy treats various forms of cancer. High doses of radiation are directed at cancer cells to shrink or kill them and to stop the cancer from spreading to other parts of the body.

The risk of having radiation enteritis increases with higher doses of radiation, a large treatment area, previous abdominal surgery, or having a diagnosis of diabetes (chronic condition affecting how your body uses blood sugar, or glucose) or hypertension (high blood pressure). Having radiation on a large portion of the intestines is also thought to increase the risk.


For those who have radiation treatment in the abdomen or pelvis, up to 90% will experience a change in their bowel habits. It’s estimated that about 15% will have chronic issues.

Radiation therapy for cancers that occur in the pelvis, abdomen, or colon may cause radiation enteritis. This is usually an acute (short-term) issue, but it can become a chronic (long-term) problem.


The symptoms of acute enteritis can include:

If radiation enteritis becomes chronic, it could also lead to signs and symptoms of:

  • Bowel obstructions (blockages in the intestine)
  • Chronic abdominal pain
  • Malabsorption (poor absorption of nutrients from food)
  • Bowel perforations (holes in the intestines)
  • Weight loss 

Side Effects

Sometimes the symptoms of enteritis can lead to complications both inside and outside the digestive system.


There are several different types of anemia, and it has many causes. Anemia is when the blood lacks healthy red blood cells to carry enough oxygen to the body’s cells.

In some cases of enteritis, bleeding in the intestines can be a problem. The bleeding may be enough to cause anemia.

Symptoms of anemia can include:

  • Dizziness
  • Fatigue
  • Headaches
  • Irregular heartbeat
  • Shortness of breath

Treating anemia might include taking iron or vitamin supplements or, in more severe cases, intravenous iron or a blood transfusion.


Having diarrhea (watery stools) can lead to dehydration. Dehydration is when too much fluid is lost from the body (such as through diarrhea and/or vomiting) and isn’t replaced through drinking.

The symptoms of dehydration can include:

  • Chapped lips
  • Dry eyes
  • Dry mouth
  • Feeling thirsty
  • Headache
  • Lack of urination
  • Muscle cramps

Partial Bowel Obstruction

One of the potentially more serious complications of enteritis is bowel obstruction. An obstruction is when the intestine starts to close on itself, which is called a stricture. As the intestine narrows, food and stool can't move through it freely and it may become blocked.

Bowel obstructions might be partial or total. In some cases, enteritis is discovered because an obstruction is occurring. Partial obstructions might be treated conservatively with bowel decompression (a tube inserted through the nose and suction applied for a few days). Others might need surgery to resolve.


For radiation enteritis, the team that provides the treatment will take steps to prevent it. Using the lowest dose possible on the smallest amount of abdomen is important in prevention. Having a full bladder during treatments might also help, as well as more technical aspects that the radiology team will put into place.

To avoid enteritis from food poisoning, it’s important to:

  • Keep utensils, cooking surfaces, and fruits and vegetables clean.
  • Keep foods hot after they’re cooked.
  • Put food away in a refrigerator right away.
  • Separate raw meat and poultry from other foods.
  • Wash hands regularly and especially before cooking.
  • Do not drink untreated water from streams, lakes, rivers, and other bodies of water.
  • When traveling to areas where bacterial infections from water are common, avoid drinking tap water. 


Treatment for radiation enteritis is usually focused on the symptoms. Diarrhea might be treated with antidiarrheal medications. Fluids and nutrition may be given through intravenous (IV) lines in the case of dehydration or malnutrition. Other types of medications such as anti-inflammatories, antibiotics, or steroids might also be used.

Further recommendations might include drinking lots of fluids, a low-fiber diet, and eating small meals several times a day. Probiotics (friendly gut bacteria) or prebiotics (nutrients that promote healthy gut bacteria) are under study as a treatment and might also be recommended by a doctor.

In acute cases of radiation enteritis, the inner layer of the small intestine might return to normal over time, which could take about six months.

In the case of infection, most of the time people will improve on their own without any treatment. Drinking lots of fluids and replacing electrolytes (salts in the blood) by drinking sports drinks or broth is often recommended.

Medications that slow down diarrhea may also be recommended. It’s important to talk to a healthcare provider before using them. If there is blood in the stool or there is a bacterial infection, an antidiarrheal medication might not be helpful.

When to Get Immediate Care

See a healthcare provider right away for symptoms such as:

  • Blood in the stool
  • Diarrhea that won’t stop
  • Dizziness or fainting
  • Lethargy or extreme fatigue
  • Severe or sudden abdominal pain
  • Vomiting that won’t stop 


Enteritis is when the small intestine becomes irritated and inflamed. This can cause diarrhea, vomiting, and blood in the stool, among other symptoms. Treatment may include dietary changes, medications, and taking in more fluids.

A Word From Verywell

Enteritis causes a lot of uncomfortable symptoms. Avoiding the germs that cause infection is something that needs special attention when cooking and handling food and when traveling. 

Radiation enteritis might be more difficult to avoid for people who have certain types of cancer, but steps can be taken to try to lessen the effects of the radiation. Talking with a healthcare provider about the symptoms, especially blood in the stool, is important in understanding the cause and getting treatment. 

Frequently Asked Questions

  • How long does enteritis last?

    Enteritis can last anywhere from a few days when caused by an infection to several months when caused by radiation treatment. In the case of chronic enteritis, it may last for much longer. 

  • Is enteritis curable?

    Yes. Enteritis from an infection may go away on its own with only home treatments. In the case of radiation enteritis, most cases are treatable. Some people may develop chronic enteritis, which may persist and need more intensive treatment.

  • How can I get tested for enteritis?

    Blood and stool tests may be used to confirm or rule out enteritis from an infection. However, food poisoning is often diagnosed based on the symptoms. 

    When symptoms become concerning, it might be necessary to do testing to see what is causing them. Imaging tests such as computed tomography (CT) which uses X-rays for a detailed image, or magnetic resonance enteroclysis (MRE) which uses magnetic fields might be helpful.

    Endoscopy, using a thin, flexible tube with a camera and a light on the end to see the inside of the digestive system, might also be used. A test in which patients swallow a pill with a camera in it, called small bowel capsule endoscopy, is also sometimes used to make a diagnosis.

7 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  3. Lu L, Li W, Chen L, et al. Radiation-induced intestinal damage: latest molecular and clinical developments. Future Oncol. 2019;15(35):4105-4118. doi:10.2217/fon-2019-0416. 

  4. National Heart, Lung, and Blood Institute. Anemia

  5. MedlinePlus. Dehydration.

  6. Guo SB, Duan ZJ. Decompression of the small bowel by endoscopic long-tube placementWorld J Gastroenterol. 2012;18(15):1822-1826. doi:10.3748/wjg.v18.i15.1822

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By Amber J. Tresca
Amber J. Tresca is a freelance writer and speaker who covers digestive conditions, including IBD. She was diagnosed with ulcerative colitis at age 16.