Overview

What is colitis?

Colitis is inflammation in your colon, which is the main part of your large intestine. Your colon is the last leg of the journey your food takes through your digestive system. Inflammation in your colon can affect the way this journey ends, causing pain, diarrhea and sometimes blood in your poop. Inflammation is your body’s response to infection or injury. It causes swelling and tenderness in your tissues.

Is colitis a serious disease?

There are different types of colitis, with different causes. Some are short-lived and easy to treat, like when you have a bacterial infection from food poisoning. Other types — called inflammatory bowel diseases — are more chronic and difficult to treat. Colitis is more serious when it doesn’t go away. A severe case can do serious damage to your colon over time. It also affects your quality of life.

Symptoms and Causes

What are the symptoms of colitis?

Common symptoms include:

Acute cases may cause:

Chronic cases may cause:

How does a person get colitis?

Different types of colitis have different causes:

Infectious colitis is caused by a viral, parasitic or bacterial infection. Salmonella and E. coli are common causes. Most people get it from eating or drinking contaminated food or water. It’s usually temporary, but some people may need antibiotics to treat certain infections.
Pseudomembranous colitis. This type of colitis is caused by a specific bacterium known as C. diff (clostridioides difficile). Ironically, people often get pseudomembranous colitis after taking antibiotics. The bacterium C. diff commonly already lives in your intestines, but certain antibiotics kill off other bacteria that help to keep it in check, causing C. diff to overgrow.
Allergic colitis. Allergic colitis affects breastfeeding babies. It’s caused by food intolerances, often to dairy milk (lactose intolerance) or soy milk (soy allergy). Proteins that breastfeeding people eat reach their babies through their breastmilk.
Ischemic colitis is a side effect of intestinal ischemic syndrome, which is when your intestines aren’t getting enough blood supply. Ischemia is usually caused by a blockage in your blood vessels, such as a blood clot, aneurysm or atherosclerosis (a buildup of plaque).
Inflammatory bowel diseases (IBD) are a group of conditions that cause chronic inflammation in your colon. They include ulcerative colitis, microscopic colitis and Crohn’s disease. These conditions don’t have a direct cause. Doctors believe they are a type of autoimmune disease, which means they cause your immune system to malfunction and attack its own tissues. Autoimmune diseases appear to be partially genetic and triggered by environmental factors.
Radiation colitis is a side effect of radiation therapy, which is used to treat certain types of cancer. It’s usually temporary, but some people develop long-term symptoms.
Diversion colitis is a side effect that can occur in people who've had a colostomy. It happens in the part of your colon that's no longer being used. Doctors believe that diverting your poop away from that part of your bowel may deprive it of certain nutrients that the tissues need to stay healthy. It only causes symptoms in a small number of people.

What are the possible complications of colitis?

Complications usually result from severe, long-term, chronic colitis. They can include:

Perforation. Chronic inflammation weakens your colon walls, making them more likely to rupture. An ulcer in your colon may wear a hole all the way through. This can cause bacteria from your colon to infect your abdominal cavity (peritonitis) and possibly your bloodstream (septicemia), which would be especially dangerous. Septicemia can lead to sepsis.
Toxic megacolon. Severe inflammation can cause the walls of your colon to dilate (widen) and interfere with its natural muscle contractions (peristalsis). This can trap food and gas in your colon (large bowel obstruction). Obstruction leads to painful abdominal distension and an increased risk of rupture.
Increased risk of colon cancer. Long-term inflammation is associated with cellular changes in your colon wall that can sometimes progress to cancerous changes. The risk increases rapidly after the first decade of chronic colitis.
Increased risk of other inflammatory diseases. People with inflammatory bowel diseases are more likely to have other inflammatory diseases in other parts of their bodies. Some examples include osteoarthritis (joint inflammation) and primary sclerosing cholangitis (inflammation in your liver and bile ducts). It appears that uncontrolled inflammation in one area may trigger a similar process somewhere else.

Diagnosis and Tests

How is colitis diagnosed?

Your healthcare provider will begin by asking you about your symptoms, when they began and what you were eating and drinking at the time. They’ll ask you about your current medications and any health conditions that you’ve been recently treated for. They’ll physically examine you, then move on to medical tests. These are likely to include blood tests, stool tests and imaging tests to look at your colon.

Blood tests involve drawing a small amount of your blood through a needle and sending it to a lab to analyze. Stool tests involve taking a sample of your poop and sending it to the lab. Proteins in your blood and stool can show evidence of inflammation and sometimes indicate a particular type of infection. Imaging tests can confirm inflammation and give more detailed information about your condition.

In particular, endoscopic tests that visualize the inside of your colon with a lighted scope can be helpful in diagnosing the type of colitis you have. Endoscopic exams, including colonoscopy and flexible sigmoidoscopy, allow healthcare providers to take tissue samples from the inside of your colon (biopsy). Healthcare providers can learn important information by examining tissue samples in the lab.

Management and Treatment

How is colitis treated?

Treatment for colitis depends on the type and the cause. It may include:

Medications. Your provider may prescribe antibiotics to treat infections, corticosteroids to treat inflammation, immune modifiers to repress your autoimmune response, and aminosalicylates to treat IBD.
Diet. If you have temporary, acute colitis, you may benefit from a low-fiber, easy-to-digest diet. If you have chronic colitis, you may need a personalized diet plan. You may need to avoid foods that trigger your colitis flare-ups and to incorporate other foods or supplements to make sure you get adequate nutrition.
Surgery. People with certain types of colitis, including necrotizing enterocolitis, ischemic colitis and IBD, may require surgery to treat complications. Surgery doesn't always cure these conditions, but it may be necessary to stop bleeding, repair a perforation or remove a blockage.

Outlook / Prognosis

Does colitis go away?

Acute colitis that is caused by a temporary infection, food intolerance or radiation exposure typically goes away by itself. Infections take about a week, while radiation colitis takes a few months. Some types of infection may need to be treated with antibiotics to go away, especially parasite infections. Allergic colitis goes away when the substance your child was allergic to has cleared from their body.

Colitis that is an acute reaction to a chronic condition needs treatment to go away. Ischemic colitis resulting from intestinal ischemic syndrome won’t go away until blood flow is restored to your colon. Diversion colitis in people with colostomies won’t go away until the colostomy is reversed and the full use of your colon is restored (anastomosis surgery). In some people, these solutions aren’t possible.

Chronic colitis that is caused by inflammatory bowel disease is a lifelong condition. It won’t go away forever, but it can go away for a while. This is called remission. Treatment for IBD is focused on improving your symptoms and making remission last as long as possible. This is also true if your colitis is caused by another condition that can’t be cured. In some cases, surgery can make it go away.

Living With

What kind of diet is helpful for living with colitis?

Your healthcare provider may suggest one or several of these diets, depending on the type of colitis you have and the condition you’re in:

Low-residue diet. A low-residue diet is easy to digest when your symptoms are acute or severe. It limits fiber and fat and emphasizes soft, well-cooked foods. If you have a temporary infection or radiation colitis, your healthcare provider may recommend a low-residue diet.
Anti-inflammatory diet. To keep chronic inflammation low, your healthcare provider might recommend you avoid highly inflammatory foods, especially fast and processed foods high in sugar and fat. They might suggest more healthy, unsaturated fats to calm inflammation like olive oil, avocados, nuts and oily fish. (The Mediterranean diet is naturally anti-inflammatory.)
Elimination diet. If you have an inflammatory bowel disease, your healthcare provider will likely recommend an elimination diet to isolate the foods that cause your symptoms to flare up. An elimination diet eliminates certain types of foods and then adds them back in a systematic way so that you can observe how your gut responds to them. After the temporary elimination diet, you can use what you learned to design a personalized, long-term maintenance diet.

A note from Cleveland Clinic

While its causes remain unknown, chronic colitis is becoming increasingly common in Western countries. We don’t entirely know why, but healthcare providers suspect that the modern Western diet may have something to do with it. High in inflammatory processed foods and saturated fats, this diet likely contributes to chronic low-grade inflammation in your intestines. You can help protect your intestines by emphasizing anti-inflammatory whole foods and unsaturated fats in your diet.

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Colitis