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Colitis: Causes, Symptoms, & How to Treat

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Written by Adam Pont, MD, PhD.
Gastroenterology Fellow, New York Presbyterian Hospital/Columbia
Medically reviewed by
Last updated May 28, 2024

Colitis quiz

Take a quiz to find out if you have colitis.

Colitis is an inflammation of the lining of the colon. There are a number of causes, including infection and an overactive immune system. Often, you have stomach pain and diarrhea. Getting the right diagnosis is critical to managing your symptoms.

Is colitis a serious disease?

Pro Tip

Colitis is not one disease with a single cause. It has several different causes. Your experience and treatment will depend on the cause. —Dr. Adam Pont

Colitis is caused by inflammation of the inner lining of the colon (large intestine). Colitis has many different causes.

It could be caused by an infection (from bacteria, parasites, or viruses). You may have overactive immune system activity. This is the case with the inflammatory bowel diseases (IBD)—Ulcerative Colitis and Crohn's Disease—as well as with microscopic colitis. You may have decreased blood flow to the colon (ischemic colitis), or previous bowel surgery (diversion colitis).

Most people with colitis experience abdominal (belly) pain and loose stool (diarrhea). With the right treatment, symptoms usually begin to improve within a week or two, though it depends on the cause of the colitis.

Most common symptoms

While symptoms depend on the form of colitis, you will likely have belly pain, loose stool, and many bowel movements. Bloating and excess gas are also common. If it's lasted for a while, you may also have weight loss and chronic fatigue.

You may notice blood in your stool. You may also have a fever, acute fatigue, and loss of appetite. It is important to keep track of your symptoms and the order in which they occur. For instance, severe, sudden abdominal pain followed by bloody loose stools is common with ischemic colitis.

Main symptoms

  • Belly pain, cramping, or discomfort
  • More frequent bowel movements with loose stools
  • Fever (more common with infections or IBD)
  • Pain while passing stool (more common with IBD)
  • The feeling of not getting all the stool out during a bowel movement (more common with IBD and some parasites)
  • Bloating
  • Blood in your stool
  • Fatigue

Other symptoms you may have

  • Fecal incontinence (stool coming out by accident)
  • Feeling lightheaded or dizzy—from dehydration caused by watery stools
  • Weight loss

These symptoms are more likely if you have IBD

  • Eye pain
  • Mouth ulcers
  • Joint pain (arthritis)

Dr. Rx

Ask your doctor: How long until my symptoms begin to improve? What should I do if my symptoms have not improved by that time? Also, how do I prevent this from happening again? —Dr. Pont

What should you do for colitis?

If you have a fever, blood in your stool, or sudden weight loss, along with frequent loose stools, immediately call your doctor (if available) or go to the ER.

If you are experiencing lightheadedness or dizziness, go to the ER or call 911.

Otherwise, make an appointment with your doctor within 2 weeks. They may then refer you to a gastroenterologist (doctors who specialize in the digestive tract), who will perform the tests ahead of a more extensive workup. A diagnosis is made by placing a camera into the intestine (e.g. sigmoidoscopy) and taking a biopsy.

Colitis causes

Colitis is caused by inflammation of the inner lining of the colon. The inflammation makes it harder for the colon to absorb water, causing loose stool and other symptoms.

There are many potential causes, including:

  • Infection with bacteria (particularly C. difficile), parasites, or viruses
  • Overactive immune response (ulcerative colitis or Crohn's disease; microscopic colitis)
  • Decreased blood flow to the colon from blood clots, narrowed arteries, or extremely low blood pressure (ischemic colitis)
  • Having a stoma or ostomy (surgery where the surgeon created an opening in your abdomen for your stool to collect outside your body). The absence of stool flow in the portion of the bowel beyond the stoma (and less exposure to certain molecules in the stool) can cause colitis.
  • Failure to evacuate stool - also called toxic megacolon, which damages the colon and can cause colitis

Pro Tip

Your gut has many billions of bacteria and other microorganisms living in it. This collection is called the “microbiome.” One potential future treatment for some forms of colitis may involve changing your microbiome by introducing new bacteria from a healthy donor—a fecal microbiota transplant. Such transplants are already being used successfully to treat certain types of infectious colitis that do not respond to repeated courses of antibiotics. —Dr. Pont

What is the best treatment for colitis?

Treatment depends on the cause. Infectious colitis is typically diagnosed with a stool sample.

For all other types, you may need to have a colonoscopy or sigmoidoscopy to confirm the diagnosis and how severe it is. A colonoscopy uses a long flexible camera to look at the inside of your colon. It is usually done under sedation. A sigmoidoscopy is a form of colonoscopy that looks only at the rectum (the end of the colon).


Once you know the cause, your doctor will probably prescribe medication to treat it acutely and put you into a stable remission. If you have bad diarrhea, you may also need to drink lots of fluids and take an over-the-counter anti-diarrheal medicine such as loperamide.

If taking antibiotics, be sure to finish the whole prescription, even if you feel better.

  • Infectious colitis (caused by a virus): no medications are usually necessary.
  • Infectious colitis (caused by a parasite or bacteria): Your doctor will prescribe an antibiotic based on which parasite or bacteria is causing the colitis.
  • Colitis from IBD: Medication will depend on many factors and sometimes your doctor will prescribe a combination of drugs. Options include oral medications and those delivered by enema. They may recommend biologic medications. These have antibodies that neutralize or block molecules in your body that are involved in inflammation. They are given by injection or through an IV.
  • Ischemic colitis: Medicines to reduce blood clots or treat low blood pressure.
  • Microscopic colitis: Your doctor may give you a steroid medication called budesonide for 4 weeks. If symptoms improve, they may reduce the dose. Your doctor may recommend changes to your diet as well.
  • Diversion colitis: You may need a medicated enema (a liquid or foam solution that you insert into your anus).

Medical procedures

  • Colitis caused by IBD: If you have ulcerative colitis and medications don’t help, your doctor may recommend surgery to remove your colon.
  • Ischemic colitis: If severe, you may need surgery to repair the colon or remove portions of it.
  • Diversion colitis: If possible, your doctor may recommend surgery to reverse the stoma or ostomy. The surgery reconnects your bowel so that your stool flows through its entire length. If this is not possible, there are other treatments to try.

Ready to treat your colitis?

We show you only the best treatments for your condition and symptoms—all vetted by our medical team. And when you’re not sure what’s wrong, Buoy can guide you in the right direction.See all treatment options
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How does a person get colitis?

Risk factors depend on the type of colitis.

Infectious colitis is more common in people with a weakened immune system. For example, patients with cancer or other conditions or medications (like steroids) are more susceptible. If you’re already taking antibiotics, that's a risk for colitis caused by C. difficile (a bacteria). Traveling to areas where parasites are common puts you at risk of infectious colitis caused by parasites.

IBD (ulcerative colitis or Crohn’s) is more likely if you have a family history of IBD or other autoimmune diseases. And having IBD also increases your risk of getting infectious colitis.

Heart disease, particularly atrial fibrillation (an irregular heartbeat) or atherosclerosis (plaques in your arteries), is a risk factor for ischemic colitis.

Microscopic colitis can be caused by certain medications (like ibuprofen) and as complications from previous colon infections.

What causes colitis in kids?

One common cause of colitis early in life —and only in rare cases, adults—is allergic colitis. It can usually be managed with changes in diet.

Colitis in infants or young age children can have different symptoms than in adults. Children may vomit, have a loss of appetite, or have signs of an allergic reaction. Call your pediatrician immediately if your child has recurrent loose bloody stools.

What are the complications of colitis?

Colitis damages the lining of the colon, which then leads to dysfunction of what the colon typically does: absorb water, nutrients, and essential molecules. Thus, colitis can lead to abdominal pain and cramping, diarrhea, often with blood and mucus, rectal bleeding, anemia due to chronic blood loss, nutritional deficiencies due to poor absorption of nutrients, rectal prolapse, fistulas, and increased risk of colon cancer. Inflammation of the colon can also co-present (with uncertain causality) with inflammation elsewhere, like the skin (episcleritis), eyes (scleritis), and joints (psoriasis).

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The stories shared below are not written by Buoy employees. Buoy does not endorse any of the information in these stories. Whenever you have questions or concerns about a medical condition, you should always contact your doctor or a healthcare provider.
Dr. Le obtained his MD from Harvard Medical School and his BA from Harvard College. Before Buoy, his research focused on glioblastoma, a deadly form of brain cancer. Outside of work, Dr. Le enjoys cooking and struggling to run up-and-down the floor in an adult basketball league.

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