What is toxic megacolon?

Toxic megacolon is a condition where part or all of the colon is inflamed and bulging larger than normal size (dilated). It may bulge because of swelling because of inflammation. The colon may also fill with gas. This condition can be a complication of severe colon disease or infection. It is a rare but life-threatening condition and needs treatment right away. It can lead to inflammation all over the body (sepsis), blood loss, and death.

What causes toxic megacolon?

Toxic megacolon is a complication of these conditions:

• Ulcerative colitis. This is a type of inflammatory bowel disease (IBD). It often affects the colon and rectum.

• Crohn’s disease. This is also a type of IBD. It can affect any part of the digestive tract.

• Colon infection. This can be caused by a bacteria (Clostridioides difficile). This germ can lead to severe diarrhea. Other infections can also cause the problem.

• HIV infection or AIDS. For people with HIV, cytomegalovirus (CMV) colitis is the leading cause of toxic megacolon.

• Ischemia. This is low blood flow to the colon.

• Colon cancer. In rare cases, cancer growths may cause the condition.

Other risk factors include:

• Diabetes

• A transplanted organ

• Kidney failure

• Weakened immune system

• Chronic obstructive pulmonary disease (COPD)

Who is at risk for toxic megacolon?

You are more at risk for toxic megacolon if you have:

• Ulcerative colitis

• Crohn’s disease

• Colon infection

• Low blood flow to the colon (ischemia)

• Colon cancer

• Diabetes

• A transplanted organ

• Kidney failure

• Weakened immune system

• COPD

What are the symptoms of toxic megacolon?

Symptoms can occur a bit differently in each person. They can include:

• Belly swelling

• Belly pain

• Diarrhea

• Fever

• Fast heart rate

• Dizziness

• Confusion

• Bloody diarrhea

The symptoms of toxic megacolon can seem like other health conditions. See your healthcare provider for a diagnosis.

How is toxic megacolon diagnosed?

Your healthcare provider will ask about your symptoms and health history. Your provider will give you a physical exam. You may also have tests, such as:

• Blood tests. These are to check for infection and other signs of problems.

• Imaging test. You may have an X-ray or CT scan of the intestine. Both of these use radiation to create images of tissues inside the body. The healthcare provider will look for abnormal dilation of the colon.

How is toxic megacolon treated?

Treatment will depend on your symptoms, your age, and your general health. It will also depend on how severe the condition is. People with toxic megacolon are often very sick. Treatment can include:

• Medicines. Treating the main condition or infection that caused the problem may help reduce toxic megacolon. You may be given medicines to help control inflammation. Antibiotics can help treat or prevent infection. Your healthcare provider may also prescribe other medicines.

• Bowel rest and decompression. These treatments help the bowel from moving and remove gases filling the colon.

• IV (intravenous) fluids. You may be given fluids and electrolytes to treat dehydration and low blood pressure.

• Surgery. If other treatments don’t reduce the size of the toxic megacolon within 2 to 3 days, you may need surgery to remove part or all of the colon.

Talk with your healthcare providers about the risks, benefits, and possible side effects of all treatments.

Your healthcare provider may have you stop taking certain medicines while you're being treated for toxic megacolon. Some medicines that can make the condition worse include:

• Opioids

• Nonsteroidal anti-inflammatory medicines (NSAIDs)

• Medicines to stop diarrhea

• Antidepressants

• Anticholinergic medicines

What are possible complications of toxic megacolon? 

If untreated, toxic megacolon can lead to severe complications such as:

• Blood loss

• Whole-body inflammation (sepsis)

• Hole in the colon (perforation)

• Loss of blood flow to organs and other tissues (shock)

• Death

When should I call my healthcare provider?

Call your healthcare provider right away if you have:

• Severe stomach pain

• Frequent diarrhea

• Bloody diarrhea

• Belly swelling

• Fever

• Fast heart rate

Key points about toxic megacolon

• A toxic megacolon is a condition where part or all of the colon is inflamed and bulging larger than normal size (dilated).

• It can be a complication of severe colon disease or infection. It is a rare but life-threatening condition and needs immediate medical treatment.

• It can lead to inflammation all over the body (sepsis), blood loss, and death.

• Symptoms can include belly swelling, diarrhea, fever, and fast heart rate.

• Treatment can include medicines, bowel rest, IV fluids, and surgery.

Next steps

Tips to help you get the most from a visit to your healthcare provider:

• Know the reason for your visit and what you want to happen.

• Before your visit, write down questions you want answered.

• Bring someone with you to help you ask questions and remember what your provider tells you.

• At the visit, write down the name of a new diagnosis and any new medicines, treatments, or tests. Also write down any new instructions your provider gives you.

• Know why a new medicine or treatment is prescribed and how it will help you. Also know what the side effects are.

• Ask if your condition can be treated in other ways.

• Know why a test or procedure is recommended and what the results could mean.

• Know what to expect if you do not take the medicine or have the test or procedure.

• If you have a follow-up appointment, write down the date, time, and purpose for that visit.

• Know how you can contact your provider if you have questions.