Toxic Megacolon: Symptoms, Causes, Diagnosis, Treatment, and Prevention
Digestive HealthUlcerative Colitis
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What Is Toxic Megacolon?

What Is Toxic Megacolon?
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Updated on August 4, 2025
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As its name suggests, toxic megacolon is a serious complication that can occur in people who have an inflammatory bowel disease (IBD) like ulcerative colitis (UC) or Crohn’s disease.

Toxic megacolon is characterized by severe inflammation that causes the colon to become dilated or stretched. The muscles in your colon may stop working, allowing food and gas to build up in the colon and toxins to leak into your bloodstream.

Eventually, this leads to systemic toxicity, says Amanda M. Johnson, MD, a gastroenterologist at Mayo Clinic in Rochester, Minnesota. “Systemic toxicity causes low blood pressure, fevers, and a high heart rate,” she says. “Because of its life-threatening nature, toxic megacolon requires immediate medical attention and treatment.”

Signs and Symptoms of Toxic Megacolon

Signs and symptoms of toxic megacolon include:

  • Swelling or pain in the stomach
  • Gas
  • Nausea
  • Vomiting
  • Dizziness or mental confusion
  • Fever
  • Rapid heart rate
  • Diarrhea, often with blood
  • Fatigue
  • Low blood pressure

If you are experiencing these symptoms, particularly if you have IBD, it's important to see your doctor right away. “A person should call their doctor or go to the emergency room if their abdominal pain becomes much more acutely severe or if the amount of bloody diarrhea is increasing,” Dr. Johnson says.

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Causes and Risk Factors of Toxic Megacolon

Toxic megacolon can be a complication of a few different diseases, says Aline Charabaty Pishvaian, MD, the director of the inflammatory bowel disease center at Sibley Memorial Hospital in Washington, DC. This includes ulcerative colitis, Crohn’s disease, and certain infections.

The most common infection that can lead to toxic megacolon is caused by a bacterium called Clostridioides difficile (C. diff), Johnson says.

The infection inflames the colon, which then distends and becomes toxic to the body. Research indicates that people with UC or Crohn’s disease are up to 5 times more likely to develop C. diff than patients without IBD.

People with uncontrolled UC or who are experiencing flares can have very intense inflammation within the wall of the colon, which puts them at higher risk for toxic megacolon, Johnson says. For this reason, the risk of toxic megacolon can be even greater in the early stages of a person’s disease.

In addition to IBD, the following conditions are linked to an increased risk of toxic megacolon:

  • Diabetes
  • HIV/AIDS
  • Kidney disease
  • Congestive heart failure
  • Chronic obstructive pulmonary disease (COPD)
  • Autoimmune disease
People using opioids, narcotics, or antidiarrheal medications to control their symptoms can also be at greater risk for toxic megacolon, Johnson says.

 “If a person with colitis is having a flare or is hospitalized, we try to avoid using opiates and antidiarrheal medications, if at all possible, for that reason,” she says.

How Is Toxic Megacolon Diagnosed?

If your doctor suspects you have toxic megacolon, they will take a complete medical history and ask about your symptoms and any medications you’re taking. They will then conduct a physical exam and look for signs of swelling and tenderness in your abdomen.

Your doctor might also request tests like a blood test that can detect elevated white blood cells or an X-ray, ultrasound, or a computed tomography (CT) scan of the belly to indicate whether the colon is dilated, Johnson says. You might also need to complete a stool test to check for infections.

Treatment and Medication Options for Toxic Megacolon

Toxic megacolon requires treatment at the hospital for a few days to stabilize the condition. You’ll likely be treated with a combination of medication, IV fluid, and bowel rest. If you don’t respond to these treatments, surgery may be needed.

Medication Options

Medication for toxic megacolon includes corticosteroids to control the inflammation and antibiotics to treat or prevent infection. Other medicines, like opioids and nonsteroidal anti-inflammatory medicines, may be stopped because of possible complications.

But if someone has IBD, the underlying disease also needs to be addressed. Steroids are often used in IBD to try to calm down the inflammation, Johnson says. “If a person has an [IBD] flare, and they also have an infection with the colon, specifically with C. diff, we need to treat the ulcerative colitis with steroids and the C. diff infection with very specific antibiotics,” she says.

Bowel Rest

Other noninvasive treatments include bowel rest, as well as IV fluids to replace lost electrolytes.

Surgery

Severe cases of toxic megacolon may require surgery to remove part or all of the colon.

"If there’s no response to medical therapy within the first few days or if there’s concern about the viability or the blood flow to the colon, or if the person is having worsening abdominal pain or any other complications due to toxic megacolon, it’s likely that they will need to have their colon removed,” Johnson says.

If you have a colectomy, you’ll likely need an ostomy as well. This is an opening in your abdomen so waste can exit your body. The ostomy may be temporary or permanent depending on the type of surgery you have.

Prevention of Toxic Megacolon

The best way to prevent toxic megacolon is to monitor and stay vigilant about your symptoms and closely follow your treatment plan for diseases like IBD that can lead to this dangerous condition.

Toxic Megacolon Prognosis

Most people survive toxic megacolon, especially if they get treatment early on. The mortality rate for toxic megacolon in people with IBD is up to 2 percent. But complications like perforation of the colon increase this risk three- to fivefold. Early surgery can greatly reduce this risk.

Complications of Toxic Megacolon

If toxic megacolon is left untreated the colon can perforate, meaning a hole can form in the colon, allowing stool to spill into the abdominal cavity, says Dr. Pishvaian. “That’s a very dangerous situation that can greatly increase the risk of death or long-term complications,” she says. “It would require emergency surgery.”

Other complications include severe gastrointestinal bleeding and blood loss.

Another risk, sepsis, is a life-threatening condition that occurs when your body releases chemicals into the bloodstream to fight off an infection, Pishvaian says. Sepsis can cause a drop in blood pressure, tissue damage, organ failure, and death.

Research and Statistics: How Many People Have Toxic Megacolon?

The incidence of toxic megacolon in the general population is unknown, but it is more common in people with IBD. While rates vary among studies, the incidence in people with Crohn’s disease or UC reported in scientific literature ranges from 1 to 10 percent.

Toxic megacolon associated with C. diff infection has also been on the rise in recent decades. Prior to 1990, there was an increase in cases from 0.4 to 3 percent. After 1990, this number rose to 4.3 percent.

Disparities and Inequities in Toxic Megacolon

There’s not much data on racial disparities in toxic megacolon specifically, but research shows they do exist when it comes to IBD outcomes and care. One study found that Black Americans with IBD over age 65 had a nearly 1.5 times higher use of emergency department services than white patients with IBD.

Another study found that compared with white people, Black people with IBD were less likely to receive advanced therapies for the disease and had higher rates of hospitalization and complications, including toxic megacolon.

The reasons for these disparities are complex and likely include socioeconomic status, education level, and insurance coverage, among others, the researchers noted.

The Takeaway

  • Toxic megacolon is a rare and potentially deadly complication that can occur in people with inflammatory bowel disease and certain infections like Clostridioides difficile.
  • Treatment options for toxic megacolon include antibiotics, corticosteroids, bowel rest, and in some cases, surgery to remove part or all of the colon.
  • If left untreated, the condition can lead to serious complications like perforation of the colon and septic shock.
  • It’s important to seek medical attention right away if you experience symptoms like severe abdominal pain and swelling, bloody diarrhea, rapid heart rate, and fever.

Common Questions & Answers

How do you know if you have toxic megacolon?
Symptoms of toxic megacolon include swelling or pain in the stomach, fever, rapid heart rate, and diarrhea, which may be bloody. If you develop these symptoms, especially if you have IBD, seek medical treatment right away.
The first-line treatment for toxic megacolon is typically a combination of medications that include antibiotics to address the infection and corticosteroids to treat inflammation, as well as bowel rest and IV fluids.
If left untreated, toxic megacolon can lead to severe complications like perforation of the colon and sepsis. If it’s not treated right away, these conditions can lead to death.
The best way to prevent toxic megacolon is to closely follow your treatment plan for diseases like IBD and infections like Clostridioides difficile.

Resources We Trust

EDITORIAL SOURCES
Everyday Health follows strict sourcing guidelines to ensure the accuracy of its content, outlined in our editorial policy. We use only trustworthy sources, including peer-reviewed studies, board-certified medical experts, patients with lived experience, and information from top institutions.
Resources
  1. Toxic Megacolon. Cleveland Clinic. July 13, 2022.
  2. Liggett M et al. Management of Severe Colitis and Toxic Megacolon. Clinics in Colon and Rectal Surgery. December 29, 2023.
  3. Voth E et al. Novel Risk Factors and Outcomes in Inflammatory Bowel Disease Patients With Clostridioides difficile Infection. Therapeutic Advances in Gastroenterology. March 12, 2021.
  4. Skomorochow E et al. Toxic Megacolon. StatPearls. July 4, 2023.
  5. Toxic Megacolon. Johns Hopkins Medicine.
  6. Toxic Megacolon. Mount Sinai.
  7. About Sepsis. Centers for Disease Control and Prevention. March 8, 2024.
  8. Segura A et al. Association of Race and Ethnicity With Healthcare Utilization for Inflammatory Bowel Disease in the United States: A Retrospective Cohort Study. American Journal of Gastroenterology. April 1, 2025.
  9. Alsabbagh Alchirazi K et al. Racial Disparities in Utilization of Medications and Disease Outcomes in Inflammatory Bowel Disease Patients. Crohn’s & Colitis 360. April 2025.
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Yuying Luo, MD, is an assistant professor of medicine at Mount Sinai West and Morningside in New York City. She aims to deliver evidence-based, patient-centered, and holistic care for her patients.

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