Toxic megacolon is a rare but potentially life-threatening complication of IBD, an infection, or damage to the colon. It involves inflammation of the deeper layers of the colon and can lead to rupture.

A person may develop toxic megacolon if their colon has inflammation due to conditions such as Crohn’s disease or ulcerative colitis, or infections such as Clostridioides difficile (C. difficile).

In this article, we look at what toxic megacolon is, its causes, symptoms, treatments, and outlook of the condition.

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The large intestine includes the appendix, colon, and rectum. It absorbs water and passes stool to the anus, which is the last stage of digestion.

Toxic megacolon is a rare condition that can cause the large intestine to malfunction. It typically develops quickly.

The term “megacolon” refers to an abnormal widening of the colon, while the term “toxic” indicates the severity of the condition.

In a person with toxic megacolon, the colon may dilate and expand. This makes it unable to remove feces or gas. If these build up inside the colon, the large intestine can rupture.

A ruptured colon can be fatal, as bacteria may release into the abdomen and cause serious infection.

Other types of noninflammatory megacolon conditions may also damage the colon. These include:

  • acute colonic ileus
  • pseudo-obstruction
  • congenital colonic dilation

The most common cause of toxic megacolon is inflammatory bowel disease (IBD). This is the term doctors and healthcare professionals use when someone is living with both Crohn’s disease and colitis.

IBD causes swelling and irritation in the digestive tract and infections in the bowel such as C. difficile colitis. People who live with these conditions are at the highest risk of developing toxic megacolon.

Some infections may also lead to toxic megacolon, including:

Medical causes may include:

Toxic megacolon can cause the colon to expand rapidly, and symptoms may develop over a short period. These can include:


Toxic megacolon can also cause complications such as:

In some circumstances, toxic megacolon can cause death.

To diagnose toxic megacolon, a doctor may ask questions regarding symptoms, perform a physical exam, and conduct several tests.

During the physical exam, the doctor will look for reduced or absent sounds in the bowel, dehydration, and abdominal tenderness. The exam may also reveal signs of septic shock, such as:

The doctor may also suggest the following tests:

Treatment for toxic megacolon will depend on its severity. A doctor or healthcare professional may treat the condition with medication or surgery.


A doctor may recommend a person stop taking medications that aggravate the condition, such as opiates. They may request a person receives IV fluids to combat dehydration. They may also prescribe antibiotics, especially if the condition is due to an infection. Doctors commonly prescribe the antibiotics vancomycin and metronidazole.

If the person has ulcerative colitis, a doctor may give them steroids such as hydrocortisone or methylprednisone.

A doctor may also require a person has “bowel rest,” which means they cannot eat any food by mouth. This is to give the digestive system time to heal. In this instance, a person may have a nasogastric tube fitted to help decompress the stomach.


A doctor will assess whether a person requires surgery based on their age, medical history, and the severity of the toxic megacolon. If a person’s colon is bleeding or perforated, or the person’s health is declining rapidly, surgery is the only viable option. If the colon is perforated, an individual’s risk of mortality increases by three to five times.

The most common surgery for toxic megacolon is subtotal colectomy with ileostomy, and either a Hartmann pouch, rectostomy, or sigmoidostomy. The table below gives more information about each.

Subtotal colectomyIn this procedure, a surgeon removes the majority of the colon, but leaves the left side of the colon intact, called the sigmoid colon. The surgeon then joins the small bowel to the sigmoid colon.
IleostomyThis procedure involves a surgeon diverting the small intestine through an opening in the abdomen, called a stoma.
Hartmann pouchIn this procedure, a surgeon seals a part of the rectum after removing part of the colon.
RectostomyThis procedure refers to a permanent opening that a surgeon creates in the rectum.
SigmoidostomyThis procedure involves a surgeon creating an artificial anus by surgically opening the sigmoid colon.

Toxic megacolon is a medical emergency, and a doctor will typically require a person with the condition to remain at the hospital for inpatient treatment.

It often requires medical intervention, at least to provide rehydration and replenish electrolytes, and in the most severe cases, surgical intervention.

A person will not typically be able to manage the condition themselves. However, they can treat conditions that may lead to toxic megacolon before they worsen.

Avoiding certain medications, taking certain medications, following a specific diet plan, and practicing rigorous food preparation and storage hygiene may help reduce and manage symptoms of IBD and infections.

The outlook for toxic megacolon may depend on how early a person seeks treatment for the condition, as well as other factors, such as:

  • age
  • cause
  • how quickly an individual receives surgery after diagnosis, if needed
  • post-surgical care

People who develop toxic megacolon as a result of infection may have a more positive outlook than those whose condition is a result of IBD.

The mortality rate in people hospitalized with toxic megacolon may be around 6.5%, according to some studies. However, mortality rates in people who receive early diagnosis, prompt medical care, and surgery may be less than 2%.

If the colon ruptures, the outlook significantly decreases, and the mortality rate increases by three to five times.

Early diagnosis and treatment significantly improve a person’s outlook, and a person with any of the symptoms of toxic megacolon should seek immediate medical care. This is especially true for people with IBD or those who have experienced an infection that affected their digestive system.

A person may develop toxic megacolon if they have colon inflammation due to conditions such as Crohn’s disease, or ulcerative colitis, or infections such as C. difficile. The colon may expand rapidly, which can prevent gas and feces from leaving the body. This can result in a colon perforation, which can be fatal.

Depending on the severity and progression of the condition, a doctor or healthcare professional may treat a person with medication in hospital, such as antibiotics and IV fluids. If a person requires surgery, a surgeon may remove part of the colon.

Toxic megacolon is a medical emergency, and anyone with symptoms should seek medical attention immediately. The outlook for the condition is significantly better for people who receive early diagnosis and treatment.