Health Encyclopedia

Toxic Megacolon

A toxic megacolon is rare, but life-threatening. It is a complication of severe colon disease or infection. 

Toxic megacolon can be deadly because it puts you at risk for infection throughout the body, shock, and dehydration. Toxic megacolon is a life-threatening condition that needs immediate treatment.


These are signs and symptoms related to toxic megacolon:

  • Swelling of the belly

  • Pain in the belly

  • Fever

  • Rapid heart rate

  • Shock

  • Diarrhea

Who’s at risk

Toxic megacolon is a complication of these conditions:

  • Ulcerative colitis. This is an inflammatory bowel disease. It usually affects the colon and rectum.

  • Crohn’s disease. This is an inflammatory bowel disease. It can affect any part of the digestive tract.

  • Infections of the colon. These can be caused by C difficile. This is a germ that can lead to symptoms ranging from diarrhea to a possibly deadly colon inflammation.

Other risk factors include diabetes, organ transplants, kidney failure, suppressed immunity, and chronic obstructive pulmonary disease.


To make a diagnosis, your health care provider will do these things:

  • Take your medical history

  • Do a physical exam

  • Order blood tests, such as a complete blood count

  • Order a stomach X-ray or a CT scan


Treatment of toxic megacolon includes:

  • Medicines. Treating the original condition or infection may help reduce toxic megacolon. Anti-inflammatory medicines can help control inflammation. Antibiotics can help treat or prevent infection. Your health care provider may prescribe other medications.

  • Bowel rest and bowel decompression. These treatments remove gas and substances filling the colon.

  • IV fluids. You may be given an IV of fluids and electrolytes to help nourish your body and prevent dehydration.

  • Surgery. If less invasive 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.

Your health care provider may have you stop taking certain medicines while you're being treated for toxic megacolon. Some medicines that can make the condition worse are opioids, nonsteroidal anti-inflammatory drugs, medications to stop diarrhea, antidepressants, and anticholinergic medicines.


If untreated, a toxic megacolon can result in severe complications, such as:

  • Bleeding and blood loss

  • Whole-body infection (sepsis)

  • Abnormal hole in the colon (perforation)

  • Shock

Toxic megacolon can be deadly if not treated.

When to call the health care provider

Seek immediate medical help or have someone call 911 if you have severe stomach pain and these symptoms:

  • Frequent diarrhea

  • Bloody diarrhea

  • Swelling in your belly

  • Fever

  • Rapid heart rate

  • Signs of shock, such as a weak pulse, cool or clammy skin, dilated eyes, confusion, and rapid or shallow breathing

Medical Reviewers:

  • Fetterman, Anne, RN, BSN
  • MMI board-certified, academically affiliated clinician