Pseudomembranous colitis

Date Updated: 09/03/2025

Overview

Pseudomembranous (SOO-doe-mem-bruh-nus) colitis is advanced inflammation of the colon that can cause serious or life-threatening diarrhea. Pseudomembranous colitis is most often caused by bacteria that produce tissue-damaging toxins.

Colitis is inflammation of the colon. Inflammation is the immune system reaction to disease or injury. An inflammatory reaction increases blood flow, releases proteins that regulate cells' defenses and delivers disease-fighting cells. Inflammation is a part of the process for healing tissues, but over time inflammation also may damage tissues.

Advanced inflammation in the colon can sometimes result in the formation of pseudomembranes. These are patches of irregular tissues lining the colon. These tissues are made up of mucus, debris from dead cells, blood-clotting material and immune system cells.

The most common cause of pseudomembranous colitis is serious infection with a bacterium called Clostridioides difficile, also called C. diff. The illness often affects people who are in the hospital for other conditions. C. diff-related diarrhea often happens during or after use of antibiotics.

Treatment includes an antibiotic that targets C. diff and steps to restore body fluids. Other treatments may help restore healthy bacteria that help protect the colon.

Symptoms

Symptoms of pseudomembranous colitis may include:

Watery diarrhea.
Pus, mucus or blood in the stool.
Severe belly cramps, pain or tenderness.
Fever.
Nausea.
Thirst, dry mouth and other symptoms of low body fluids, called dehydration.

The beginning of symptoms is often related to recent antibiotic treatment. Symptoms may start during or after treatment. Most often, symptoms appear within two weeks of antibiotic treatment and rarely, after 10 weeks.

When to see a doctor

If you are currently taking or have recently taken antibiotics and you develop diarrhea, contact your healthcare professional. Also, see your healthcare professional anytime you have severe diarrhea with a fever, painful stomach cramps, or blood or pus in your stool.

Causes

C. difficile bacterium

The most common cause of pseudomembranous colitis is the bacterium Clostridioides difficile, also called C. diff. In some cases, a C. diff infection is mild to moderate. Pseudomembranous colitis is a sign of more serious disease.

C. diff bacteria enter the body through the mouth. When they reach the part of the large intestine, called the colon, the bacteria can release toxic spores that damage tissues. These toxins destroy cells, disrupt colon function and cause watery diarrhea.

Outside the colon, the bacteria aren't active. They can live for a long time in places such as:

Human or animal feces.
Surfaces in a room.
Unwashed hands.
Soil.
Water.
Food.

When bacteria once again find their way into a person's digestive system, they become active again and cause infection. Because C. diff can survive outside the body, the bacteria spread easily.

The role of antibiotics

Typically, the colon has many types of bacteria that play a role in digestion. They generally keep each other in check, and the colon has other means to protect from possibly harmful bacteria.

Antibiotics can kill the good bacteria and change other factors that protect the colon. If a person already has C. diff or is newly exposed to C. diff, the germs have a chance to thrive and cause disease.

Any antibiotic may create conditions that allow C. diff to grow. But antibiotics that fight many different types of bacteria, called broad spectrum antibiotics, are often linked to C. diff-related diarrhea. These include:

Fluoroquinolones, such as ciprofloxacin (Cipro) and levofloxacin.
Penicillins, such as amoxicillin and ampicillin.
Clindamycin (Cleocin).
Cephalosporins, such as cefixime (Suprax).

Other factors in C. diff infection

Other factors can create conditions in the colon that make C. diff infection more likely. These include:

Chemotherapy to treat cancer.
Inflammatory bowel disease.
Cancers or other diseases affecting the immune system.
Kidney disease.
Medicines that reduce stomach acid, called proton pump inhibitors.

Other causes

Less common causes of pseudomembranous colitis include:

Other bacteria, including Klebsiella oxytoca or Staphylococcus aureus.
Viruses, including cytomegalovirus and coronavirus.
Parasites.
Inflammatory bowel disease.
Cocaine.
Chemicals used in some medical procedures.
Reduced blood supply to the colon related to blood vessel disease.

Risk factors

Factors that may increase the risk of pseudomembranous colitis include:

Antibiotic use.
Long stays in a hospital or nursing home.
Older age, especially over 65 years.
A weakened immune system.
Intestinal surgery.
Chemotherapy treatment for cancer.

Complications

Treatment of pseudomembranous colitis is usually successful. However, even with prompt diagnosis and treatment, pseudomembranous colitis can be life-threatening. Possible complications include:

Dehydration. Diarrhea can lead to a serious loss of fluids and essential minerals. This condition, called dehydration, makes it difficult for your body to function and can cause dangerously low blood pressure. Serious dehydration can cause the kidneys or other organs to lose their ability to work.
Toxic megacolon. In this rare condition, your colon is unable to get rid of gas and stool, causing it to become greatly enlarged. Left untreated, your colon may rupture, causing bacteria from the colon to spread. An enlarged or ruptured colon requires emergency surgery and may be fatal.
A hole in your large intestine, called bowel perforation. This is rare and results from extensive damage to the lining of your large intestine or after toxic megacolon. A perforated bowel can spread bacteria, leading to a life-threatening infection.
Death. Even mild to moderate C. difficile infections can quickly progress to fatal disease if not treated quickly.

In addition, pseudomembranous colitis may sometimes return, days or even weeks after apparently successful treatment.

Prevention

To help prevent the spread of C. difficile, hospitals and other healthcare facilities follow strict infection-control guidelines. If you have a friend or family member in a hospital or nursing home, follow hygiene guidelines and ask questions if you see someone not following guidelines.

Preventive measures include:

Handwashing. Healthcare workers should practice good hand hygiene before and after treating each person in their care. In the event of a C. difficile outbreak, using soap and warm water is a better choice for hand hygiene, because alcohol-based hand sanitizers do not effectively destroy C. diff spores. Visitors to hospitals or nursing homes also should wash their hands with soap and warm water before and after leaving the room or using the bathroom.
Contact precautions. People who are hospitalized with C. difficile have a private room or share a room with someone who has the same illness. Hospital staff and visitors wear disposable gloves and isolation gowns while in the room until at least 48 hours after diarrhea ends.
Thorough cleaning. In any setting, all surfaces should be carefully disinfected with a product that contains chlorine bleach, which kills C. diff spores.
Use antibiotics only when necessary. Antibiotics are sometimes prescribed for an illness that may be caused by a virus, but antibiotics can't be treated with these illnesses. Take a wait-and-see attitude with simple ailments. If you do need an antibiotic, ask your healthcare professional if you can take one not likely to increase the risk of C. diff-related diarrhea.

Diagnosis

Tests and procedures that may be used to diagnose the cause of diarrhea:

Stool sample. There are different stool tests used to detect C. diff bacteria or their toxins or other disease-causing germs or parasites that can cause pseudomembranous colitis. This is the primary test for diagnosing a C. diff infection.
Blood tests. These may reveal an unusually high white blood cell count, called leukocytosis, which may indicate an infection such as C. difficile if you also have diarrhea.
Colonoscopy or flexible sigmoidoscopy. A tube with a miniature camera at its tip is used to examine the inside of your colon. A tool may be used to remove a tissue sample, called a biopsy. These tissue samples may be tested in a lab to identify causes other than C. diff. A colonoscopy is an exam of the entire colon. A flexible sigmoidoscopy is an exam of a part of the colon.
Imaging tests. An X-ray or CT scan may be used to look for serious complications of pseudomembranous colitis, such as toxic megacolon or bowel perforation.

Treatment

Treatments for pseudomembranous colitis usually include:

Treating dehydration. Treating dehydration. Fluids and essential minerals are delivered through a tube inserted in a vein. This restores typical fluid levels.
Stopping the use of antibiotics. If pseudomembranous colitis is linked to an antibiotic, use of that medicine is stopped unless it's critical for treating another condition. Other medicines may be stopped if they are likely linked to the condition.
Taking another antibiotic targeting C. diff. You'll likely take an antibiotic that targets C. diff but not the broad range of bacteria in the colon. This treats the C. diff infection but allows other bacteria to recover. More than one round of treatment may be needed. Commonly used antibiotics include:
- Vancomycin
- Fidaxomicin (Dificid)
- Metronidazole (Flagyl)
Preventing recurring C. diff infections. Bezlotoxumab is a human monoclonal antibody, a medicine that supports the immune system. When there is a risk of a repeat infection, this may be used with antibiotic treatment to prevent another C. diff infection.

When antibiotic treatments don't work, your healthcare team may look for other possible causes for pseudomembranous colitis or try other treatments.

Restoring healthy bacteria

Sometimes treatments may be used to restore healthy bacteria in the colon. Stool from a healthy donor — often from stool banks — are screened to make sure they don't carry harmful germs. This stool with healthy bacteria is transplanted into the diseased colon to restore typical gut bacteria. This is called fecal microbiota transplantation.

The stool with healthy bacteria is delivered to the colon with a scope that passes through the anus. Or the transplant is delivered through a tube that passes through the nose and down to the stomach.

Two other methods to restore healthy bacteria include:

An enema that introduces healthy bacteria into the rectum.
A pill that delivers inactive bacteria that are then activated when they reach the intestines.

Surgery

Serious damage to the colon, rupture or toxic megacolon may require surgery. Procedures may include:

Removing all of the colon, so that stool is emptied from the small intestine through a hole in the belly wall and into a bag.
Removing a diseased section of the colon and connecting the remaining healthy portions.
Redirecting the stool into an opening in the belly wall, cleaning the diseased part of the colon through a second opening, and treating it with antibiotics. If the diseased portion heals, the colon may be restored to its original form.

Preparing for your appointment

Pseudomembranous colitis is often diagnosed when you are already under care in a hospital or nursing home. Diagnosis and treatment are then a continuation of current care. You also may see your primary healthcare professional first.

What you can do

If you are seeing your primary healthcare professional for diarrhea, you can write down the following information before your appointment:

Your symptoms, including any that seem unrelated to the reason for your appointment.
Key personal information, including major stresses, recent life changes and family medical history.
All medicines, vitamins or other supplements you take, including the doses.
Questions to ask your healthcare professional.

Some basic questions you might want to ask include:

What's the most likely cause of my symptoms?
What tests do I need?
Is my condition likely temporary or long lasting?
What treatments are available and which do you recommend for me?
I have other health conditions. How can I best manage them together?
Are there restrictions I need to follow?
Should I see a specialist?
Are there brochures or other printed material I can have? What websites do you recommend?

Don't hesitate to ask additional questions. And, if possible, take a family member or friend along to help you remember the information you're given.

What to expect from your doctor

Your healthcare professional is likely to ask you several questions, such as:

When did you first begin experiencing signs and symptoms?
Do you have diarrhea?
Is there blood or pus in your stools?
Do you have a fever?
Are you having stomach pain?
Have your symptoms stayed the same or gotten worse?
During the last several weeks, have you taken antibiotics, had a surgical procedure or been hospitalized?
Is anyone at home sick with diarrhea, or has anyone at home been hospitalized in the last several weeks?
Have you ever been diagnosed with diarrhea related to C. diff or antibiotics?
Do you have inflammatory bowel disease?
Are you being treated for any other medical conditions?
Have you traveled recently to an area with an unsafe water supply?
Does anything seem to improve your symptoms?
What, if anything, appears to worsen your symptoms?

What you can do in the meantime

While you're waiting for your appointment, drink plenty of fluids to help prevent dehydration. Sports drinks, oral rehydration solutions (Pedialyte, Ceralyte, others), noncaffeinated soft drinks, broths and fruit juices are good options.