Colitis
Colitis is swelling (inflammation) of the large intestine (colon).
Causes
Most of the time, the cause of colitis is not known.
Causes of colitis include:
- Infections caused by a virus or a parasite
- Food poisoning due to bacteria
Food poisoning
Food poisoning occurs when you swallow food or water that contains bacteria, parasites, viruses, or the toxins made by these germs. Most cases are c...
ImageRead Article Now Book Mark Article - Crohn disease
Crohn disease
Crohn disease is a disease where parts of the digestive tract become inflamed. It most often involves the lower end of the small intestine and the be...
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Ulcerative colitis
Ulcerative colitis is a condition in which the lining of the large intestine (colon) and rectum become inflamed. It is a form of inflammatory bowel ...
ImageRead Article Now Book Mark Article - Lack of blood flow to the colon (ischemic colitis)
- Past radiation to the colon (radiation colitis and strictures)
- Necrotizing enterocolitis in newborns
Necrotizing enterocolitis
Necrotizing enterocolitis (NEC) is the death of tissue in the intestine. It occurs most often in premature or sick babies.
ImageRead Article Now Book Mark Article - Pseudomembranous colitis caused by Clostridium difficile infection (now called Clostridiodes difficile)
Pseudomembranous colitis
Pseudomembranous colitis refers to swelling or inflammation of the large intestine (colon) due to an overgrowth of Clostridioides difficile (C diffic...
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Symptoms
Symptoms can include:
- Abdominal pain and bloating that may be constant or come and go
Abdominal pain
Abdominal pain is pain that you feel anywhere between your chest and groin. This is often referred to as the stomach region or belly.
ImageRead Article Now Book Mark ArticleBloating
Abdominal bloating is a condition in which the belly (abdomen) feels full and tight. Your belly may look swollen (distended).
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Bloody stools
Black or tarry stools with a foul smell are a sign of a problem in the upper digestive tract. It most often indicates that there is bleeding in the ...
ImageRead Article Now Book Mark Article - Constant urge to have a bowel movement (tenesmus)
- Dehydration
Dehydration
Dehydration occurs when your body does not have as much water and fluids as it needs. Dehydration can be mild, moderate, or severe, based on how much...
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- Fever
Exams and Tests
The health care provider will perform a physical exam. You will also be asked questions about your symptoms, such as:
- How long have you had the symptoms?
- How severe is your pain?
- How often do you have pain and how long does it last?
- How often do you have diarrhea?
- Have you traveled recently?
- Have you taken antibiotics recently?
Your provider may recommend a flexible sigmoidoscopy or colonoscopy. During this test, a flexible tube is inserted through your rectum to examine your colon. You may have biopsies taken during this exam. Biopsies may show changes related to inflammation. This can help determine the cause of colitis.
Sigmoidoscopy
Sigmoidoscopy using a flexible scope is a procedure used to see inside the sigmoid colon and rectum. The sigmoid colon is the area of the large inte...

Colonoscopy
A colonoscopy is an exam that views the inside of the colon (large intestine) and rectum, using a tool called a colonoscope. The colonoscope has a sm...

Other studies that can identify colitis include:
- CT scan of the abdomen
CT scan of the abdomen
An abdominal CT scan is an imaging method. This test uses x-rays to create cross-sectional pictures of the belly area. CT stands for computed tomog...
ImageRead Article Now Book Mark Article - MRI of the abdomen
MRI of the abdomen
An abdominal magnetic resonance imaging scan is an imaging test that uses powerful magnets and radio waves. The waves create pictures of the inside ...
ImageRead Article Now Book Mark Article - Barium enema
Barium enema
Barium enema is a special x-ray of the large intestine, which includes the colon and rectum.
ImageRead Article Now Book Mark Article - Stool culture
Stool culture
A fecal culture is a lab test to find organisms in the stool (feces) that can cause gastrointestinal symptoms and disease.
ImageRead Article Now Book Mark Article - Stool examination for ova and parasites
Stool examination for ova and parasites
Stool ova and parasites exam is a lab test to look for parasites or eggs (ova) in a stool sample. The parasites are associated with intestinal infec...
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Treatment
Your treatment will depend on the cause of the disease.
Outlook (Prognosis)
The outlook depends on the cause of the problem.
- Crohn disease is a chronic condition which has no cure but can be controlled. Biologic agents are very effective in controlling symptoms of Crohn colitis.
- Ulcerative colitis can usually be controlled with medicines. If not controlled, it can be cured by surgically removing the colon.
- Viral, bacterial, and parasitic colitis can be cured with appropriate medicines.
- Pseudomembranous colitis can usually be cured with appropriate antibiotics.
Possible Complications
Complications may include:
- Bleeding with bowel movements
- Perforation of the colon
- Toxic megacolon
Toxic megacolon
Toxic megacolon occurs when swelling and inflammation spread into the deeper layers of your colon. As a result, the colon stops working and widens. ...
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When to Contact a Medical Professional
Contact your provider if you have symptoms such as:
- Abdominal pain that does not get better
- Blood in the stool or stools that look black
- Diarrhea or vomiting that does not go away
- Swollen abdomen
Reviewed By
Michael M. Phillips, MD, Emeritus Professor of Medicine, The George Washington University School of Medicine, Washington, DC. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
Ananthakrishnan AN, Regueiro MD. Management of inflammatory bowel diseases. In: Feldman M, Friedman LS, Brandt LJ, eds. Sleisenger and Fordtran's Gastrointestinal and Liver Disease. 11th ed. Philadelphia, PA: Elsevier; 2021:chap 116.
Lichtenstein GR. Inflammatory bowel disease. In: Goldman L, Cooney KA, eds. Goldman-Cecil Medicine. 27th ed. Philadelphia, PA: Elsevier; 2024:chap 127.
Pardi DS, Cotter TG. Other diseases of the colon. In: Feldman M, Friedman LS, Brandt LJ, eds. Sleisenger and Fordtran's Gastrointestinal and Liver Disease. 11th ed. Philadelphia, PA: Elsevier; 2021:chap 128.