Colitis occurs when your large intestine is inflamed. It can cause pain and other symptoms, including ulcers, bloating, and diarrhea. Different types of colitis require different treatments.

Colitis is inflammation of your colon, also known as your large intestine. If you have colitis, you’ll feel discomfort and pain in your abdomen. This discomfort may be mild and reoccurring over a long period of time, or severe and appearing suddenly.

There are different types of colitis, and treatment varies depending on what type you have.

The types of colitis are categorized by what causes them.

1. Ulcerative colitis

Ulcerative colitis (UC) is one of two conditions classified as inflammatory bowel disease. The other is Crohn’s disease.

UC is a lifelong disease that causes inflammation and bleeding ulcers within the inner lining of your large intestine. It generally begins in the rectum and spreads to the colon.

UC is the most commonly diagnosed type of colitis. It occurs when the immune system overreacts to bacteria and other substances in the digestive tract, but experts don’t know why this happens.

Common types of UC include:

2. Pseudomembranous colitis

Pseudomembranous colitis (PC) occurs from overgrowth of the bacterium Clostridium difficile (C. diff). This kind of bacteria normally lives in the intestine, but it doesn’t cause problems because it’s balanced by the presence of “good” bacteria.

Certain medications, especially antibiotics, may destroy healthy bacteria. This allows C. diff to take over, releasing toxins that cause inflammation.

3. Ischemic colitis

Ischemic colitis (IC) occurs when blood flow to the colon is suddenly cut off or restricted. Blood clots can be a reason for sudden blockage. Atherosclerosis, or buildup of fatty deposits in the blood vessels that supply the colon, is usually the reason for returning IC.

This type of colitis is often the result of underlying conditions. These may include:

Although it’s rare, IC may occur as a side effect of taking certain medications such as fibrates and nonsteroidal anti-inflammatory drugs (NSAIDs). More research is needed to fully understand all medications that could be a contributing factor.

4. Microscopic colitis

Microscopic colitis is a medical condition that a doctor can only identify by looking at a tissue sample of the colon under a microscope. A doctor will look for signs of inflammation, such as lymphocytes, which are a kind of white blood cell.

Doctors sometimes classify microscopic colitis into two categories: lymphocytic and collagenous colitis.

Lymphocytic colitis is when a doctor identifies a significant number of lymphocytes. However, the colon tissues and lining are not abnormally thickened.

Collagenous colitis occurs when the colon’s lining becomes thicker than usual due to a buildup of collagen under the outermost layer of tissue.

Doctors do not know exactly what causes microscopic colitis. However, they do know some people are more at risk for the condition. People at a higher risk include:

The most common symptoms of microscopic colitis are:

  • chronic watery diarrhea
  • abdominal bloating
  • abdominal pain

5. Allergic colitis in infants

Allergic colitis is a condition that can occur in infants, usually within the first months after birth. The condition can cause symptoms in infants including:

  • reflux
  • excessive spitting up
  • fussiness
  • possible flecks of blood in a baby’s stool

Doctors don’t know exactly what causes allergic colitis. One of the most popular theories is that infants with allergic colitis have an allergic or hypersensitive reaction to certain components in breast milk. A 2020 review of studies indicated that a protein allergy, either through breast milk, cow’s milk, or formula, could contribute.

Eosinophilic colitis is a type of allergic colitis that can also show up in infants with these symptoms. Its causes are similarly unknown, but it’s likely also related to a protein allergy.

Doctors will often recommend an elimination diet for the birthing parent, which involves slowly cutting out certain foods known to contribute to allergic colitis. Examples include cow’s milk, eggs, and wheat. If the baby stops having symptoms of allergic colitis, these foods were likely causing the problem.

In severe cases, monoclonal antibodies, such as those used to help treat inflammatory bowel disease (IBD), may also be another treatment option.

Additional causes

Other causes of colitis include infection from parasites, viruses, and food poisoning from bacteria. You may also develop the condition if your large intestine has been treated with radiation.

Different risk factors are associated with each type of colitis.

You’re more at risk for UC if you:

  • are between the ages of 15 and 30 (most common) or 60 and 80
  • are white or of Ashkenazi Jewish descent
  • have a family member with UC

You’re more at risk for PC if you:

You’re more at risk for IC if you:

Depending on your condition, you may experience one or more of the following symptoms:

  • abdominal pain or cramping
  • bloating in your abdomen
  • unexpected weight loss
  • diarrhea with or without blood
  • blood in your stool
  • urgent need to move your bowels
  • chills or fever
  • vomiting

A doctor may ask about the frequency of your symptoms and when they first started. The doctor will perform a thorough physical exam and use diagnostic tests such as:

  • colonoscopy, which involves threading a camera on a flexible tube through the anus to view the rectum and colon
  • sigmoidoscopy, which is similar to a colonoscopy but shows only the rectum and lower colon
  • stool samples
  • abdominal imaging such as MRI or CT scans
  • ultrasound, which can be useful depending on the area being scanned
  • barium enema, an X-ray of the colon after it’s injected with barium, which helps make images more visible

Treatments aim to reduce symptoms and can vary by factors such as:

  • type of colitis
  • age
  • overall physical condition

Bowel rest

Limiting what you consume by mouth can be useful, especially if you have IC. Taking fluids and other nutrition intravenously may be necessary during this time.


Your doctor may prescribe various medications to help manage colitis symptoms. These may medications include:

  • anti-inflammatory medication such as 5-aminosalicylates or corticosteroids to treat swelling and pain
  • immune system suppressors such as tofacitinib (Xeljanz), azathioprine (Azasan, Imuran), or cyclosporine (Gengraf, Neoral, Sandimmune)
  • biologics such as infliximab (Remicade), adalimumab (Humira), and ustekinumab (Stelara)
  • antibiotics to treat infection
  • pain medications
  • antidiarrheal medications
  • antispasmodic drugs
  • supplements for nutritional deficiencies


Surgery for colitis could include removing part or all of your colon or rectum. This may be necessary if other treatments don’t work. These surgeries could include:

  • ileal pouch-anal anastomosis (IPAA), in which the ileum (the end of the small intestine) is turned into a pouch that then connects to the anal canal
  • proctocolectomy, in which the colon (and sometimes the rectum) are removed
  • ileostomy, in which the ileum is connected to the abdominal wall, and a stoma (an opening in the abdomen) is created to allow waste to leave the body
  • continent ileostomy, in which the end of the ileum is secured inside the interior of the abdomen. This is a possible but uncommon surgical procedure for colitis.

The only definitive way to prevent a colitis flare-up is to have surgery. If you’re looking to prevent flare-ups without surgery, there are ways to decrease their likelihood:

  • Keep a food log to track which foods may cause an increase in symptoms.
  • Ask your doctor if you should change your fiber intake and how much to eat.
  • Ask your doctor if eating smaller meals more frequently will help you.
  • Increase your activity levels if you can.
  • Learn ways to help manage stress such as meditation, yoga, and mindfulness exercises.
  • Always take medications as prescribed and tell your doctor if you have not.
  • Make sure your doctor knows about all of your other medications and supplements, including vitamins.

Always check with your doctor before changing your diet or adding any new supplements.

While every person may experience diarrhea and abdominal cramps from time to time, speak with a doctor if you have diarrhea that does not seem to be related to an infection, fever, or any known contaminated foods.

Other symptoms that indicate it’s time to see a doctor include:

  • joint pain
  • rashes that have no known cause
  • small amount of blood in your stool, such as slightly red-streaked stool
  • stomach pain that keeps coming back
  • unexplained weight loss

Seek immediate medical attention if you see a significant amount of blood in your stool.

In all cases, early detection is critical to recovery. Early detection may help prevent other serious complications.

If you feel that something is not right with your stomach, it’s best to talk with a doctor. Listening to your body is important to staying well.

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