Toxic Megacolon Is a Complication of IBD

This life-threatening complication is more common in ulcerative colitis

Toxic megacolon (also known as toxic dilation) is a serious complication of inflammatory bowel disease (IBD). This complication occurs more often with ulcerative colitis than it does with Crohn's disease. The good news is that toxic megacolon is rare and occurs in less than 5 percent of cases of severe IBD.

The condition occurs when the colon becomes severely distended, or inflated, and subsequently loses sufficient blood flow. Without adequate blood going to the colon, the tissue may become ischemic, which means that it is dying.

Treating IBD flare-ups before they become severe may help in preventing toxic megacolon. In most cases, people with ulcerative colitis are also advised to be careful with anti-diarrheal medications because these drugs have also been linked to toxic megacolon. Anyone with IBD who experiences severe abdominal pain, a swollen abdomen, and fever should seek medical attention immediately.

Close up of doctor examining stomach of senior man
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Toxic megacolon can be a spontaneous occurrence in people with particularly severe IBD. In some cases, it can result from the overuse of certain drugs, including narcotics; drugs used for pain relief, anticholinergics; drugs used for depression, anxiety and nervousness; and antidiarrheals, such as loperamide.

For this reason, it is usually recommended that people with ulcerative colitis do not take over-the-counter antidiarrheal medications without consent from, and close supervision by, a gastroenterologist that is experienced in treating patients with IBD.


Presentations of toxic megacolon include:

  • Abdominal pain and tenderness
  • Distended abdomen
  • Rapid heart rate
  • Decreased blood pressure
  • Leukocytosis (high white blood cell count)
  • Evidence of colonic distension on abdominal X-ray
  • Fever
  • Dehydration

People with toxic megacolon often appear quite ill and have a history of several days of diarrhea and abdominal pain.


Early treatment is important in toxic megacolon to avoid life-threatening complications, such as shock, colon perforation (a tear in the colon wall), peritonitis (infection in the abdomen) and bacteremia or septicemia (infection in the blood).

Left untreated, the colon may rupture, a condition that is fatal in 30 percent of cases. When treated effectively in the early stages, toxic megacolon has a lower mortality rate.This is why it is important to get any new symptoms of IBD checked out by a doctor, and to get severe symptoms dealt with immediately.

The bowel must be decompressed, which is usually accomplished by passing a tube from outside the body into the colon. If the patient is dehydrated or in shock, IV therapy may be used to replace electrolytes and fluids. Since a rupture may cause a serious infection, antibiotics may also be given. Corticosteroids can help suppress the inflammation in the colon.

In severe cases that do not respond to treatment, an emergency partial or total colectomy may be necessary. In a total colectomy, also called a proctocolectomy, the entire colon is removed. A proctocolectomy may be preferred in people with ulcerative colitis, as a j-pouch can then be created during a second surgery, after the recovery from toxic megacolon.

The j-pouch procedure will obviate the need for a permanent ileostomy. Since a proctocolectomy is also a surgical treatment for severe ulcerative colitis, the ulcerative colitis will not recur after surgery.

Although it is not recommended for most cases of Crohn's disease (as the Crohn's disease may recur in the ileal pouch), a proctocolectomy may be considered for some patients who don't have a history of perianal or small bowel disease.

In most cases, once the toxic megacolon has been effectively treated, the prognosis is very good. This complication is rare with IBD and while not always preventable, some of the causes are known and might be avoided.

A Word From Verywell

Toxic megacolon is serious but it is important to remember that it is not common and it is rarely fatal. There are a few potential causes, and discussing them with a gastroenterologist is a good idea, especially if there's any worry about developing this complication.

Most people who have toxic megacolon will be treated effectively and will recover well without more complications. Complications such as this are the reason why it is important to bring up any new symptoms, or symptoms that are getting worse, to a gastroenterologist, as soon as possible.

7 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Autenrieth DM, Baumgart DC. Toxic megacolon. Inflamm Bowel Dis. 2012;18(3):584-91.

  2. Codipilly DC, Chedid V, Beyder A. 47-year-old man with abdominal pain and diarrheaMayo Clinic Proceedings. 2018;93(1). doi:10.1016/j.mayocp.2017.02.023

  3. Dumitru IM, Dumitru E, Rugina S, Tuta LA. Toxic megacolon - a three case presentation. J Crit Care Med (Targu Mures). 2017;3(1):39-44. doi:10.1515/jccm-2017-0008

  4. Sayedy L, Kothari D, Richards RJ. Toxic megacolon associated Clostridium difficile colitis. World J Gastrointest Endosc. 2010;2(8):293-297. doi:10.4253/wjge.v2.i8.293

  5. Strong SA. Management of acute colitis and toxic megacolon. Clin Colon Rectal Surg. 2010;23(4):274-284. doi:10.1055/s-0030-1268254

  6. Rubin DT, Ananthakrishnan AN, Siegel CA, Sauer BG, Long MD. ACG clinical guideline: ulcerative colitis in adults. Am J Gastroenterol. 2019;114(3):384-413. doi:10.14309/ajg.0000000000000152

  7. Bemelman WA, Warusavitarne J, Sampietro GM, et al. ECCO-ESCP consensus on surgery for Crohn's Disease. J Crohns Colitis. 2018;12(1):1-16. doi:10.1093/ecco-jcc/jjx061

Additional Reading
  • Zheng WY, Qian JM, Yang HX, Zhu F, Li JN. "Toxic megacoloncomplicated byulcerative colitisin six patients: a case report and literature review." Zhonghua Nei Ke Za Zhi. 2012 Sep;51:694-697.

By Amber J. Tresca
Amber J. Tresca is a freelance writer and speaker who covers digestive conditions, including IBD. She was diagnosed with ulcerative colitis at age 16.