Ulcerative Colitis and C. diff Infection: What's the Link?

Medically Reviewed by Sabrina Felson, MD on June 09, 2024
5 min read

C. diff (Clostridioides difficile) infection is a bacterial infection in the colon that can cause serious illness, even death. This increasingly common infection causes almost 500,000 illnesses each year in the United States. Many of those are repeat infections.

The CDC says 1 in 6 patients treated for a C. diff infection will get it again 2-8 weeks later. Up to 5.7% of people in the hospital with ulcerative colitis have a C. diff infection.  

You may have heard the infection referred to as Clostridium difficile. The name was changed in 2016.

C. diff is everywhere – in the environment (water, soil, animal feces) – and in the intestines of many people. Your gut has trillions of microorganisms, including bacteria, fungi, and viruses. Most healthy people have a good balance of “helpful” intestinal bacteria and harmful bacteria, including C. diff. If anything happens to mess up the balance in the gut, the harmful bacteria can spread.

Antibiotics are one cause of such an imbalance. Antibiotics kill harmful bacteria but also kill helpful bacteria. Another cause is ulcerative colitis. Upsetting the balance can allow C. diff to grow and release toxins that attack the intestinal wall.

C. diff infections spread easily, most often in hospitals, long-term care facilities, and other buildings where people are sick or in a weakened state. If a patient or resident has C. diff in their stool and if they or their caregiver don’t wash their hands really well, they can leave the bacteria on anything they touch. Someone else then touches the contaminated surface. When they touch their face or prepare food without washing their hands properly, the bacteria can enter their body or spread to others.

While most people who get C. diff infections are in health care facilities, it is different for people with inflammatory bowel disease (IBD) – the umbrella term for ulcerative colitis and Crohn’s disease. About 75% of people with IBD get C. diff from their community.

C. diff infection is one of the most common complications to watch for if you have ulcerative colitis. It can happen even if you are not taking antibiotics, especially if you take steroid medications to keep the disease under control. A database of patients with IBD showed 10% will have at least one C. diff infection over the course of their lifetime. Half will have more than one.

When people with ulcerative colitis get a C. diff infection, they are more likely to need a colectomy, which is an operation to remove part or all of the colon. They also have a higher risk of developing complications after surgery,  and they have a higher death rate.

C. diff infection symptoms begin with frequent, watery, foul-smelling bowel movements and cramps in your abdomen.

If the infection goes untreated or gets worse even after treatment, symptoms can include:

  • Diarrhea or watery stool as many as 15 times a day
  • Blood in the stool
  • Worsening cramps
  • Signs of dehydration  (increase in thirst, decrease in urination, dark-colored urine, confusion)
  • Nausea
  • Fever
  • Weight loss
  • Swelling of the abdomen
  • Rapid heartbeat

C. diff infections can cause a serious complication called Clostridioides difficile colitis, which is inflammation of the colon wall. It also can cause toxic megacolon, which damages the deeper layers of the colon. People with uncontrolled ulcerative colitis are also at increased risk for toxic megacolon. If left untreated, it can cause the colon wall to rupture, releasing bowel contents into the abdomen.



C. diff is shed in stool, so if you have symptoms of an infection, stool sample tests will show which strain of the bacteria is present and if there are any toxins.

It’s not common, but if your doctor wants to confirm you have a C. diff infection, they could refer you for a colonoscopy or flexible sigmoidoscopy. These tests allow your doctor to look at the colon walls. X-rays or CT scans could also show signs of damage to the colon.

Although C. diff infections are often caused by antibiotic use, the only way to treat the infection is with more antibiotics. The medications commonly used for C. diff infections are metronidazole (Flagyl) and vancomycin (Firvanq, Vancocin HCL). A third, more expensive option, fidaxomicin (Dificid), may be used if neither metronidazole nor vancomycin work.

In severe cases, especially if the infection causes toxic megacolon, you might need surgery to remove damaged parts of the bowel.

If you get C. diff infections that come back, your doctor may suggest other treatments in addition to antibiotics, including:

Fecal microbiota transplant (FMT): Donor stool is introduced into your colon through a colonoscopy or, occasionally, by a nasoduodenal tube, inserted through your nose and threaded down to the upper part of your bowel. The healthy bacteria in the donor stool spread in your colon and fight the harmful bacteria.

Probiotics: Although not proven to help manage C. diff infections, many people believe that probiotics, which contain healthy bacteria, help counteract harmful bacteria.

Antibody therapy: Certain antibodies can provide immunity against the toxins produced by C. diff bacteria. A combination of the medications actoxumab and bezlotoxumab can help reduce the chances of the infection coming back.

Since C. diff infections can cause serious complications for people with ulcerative colitis, the outlook can be challenging. While not common, C. diff infections do cause more deaths among people with IBD  than those without, especially if they need surgery. They also tend to have to stay longer in the hospital and need more surgeries. But with vigilance and treatment, most people start to feel better within 3 days of starting treatment.  

If you have ulcerative colitis and have any symptoms of C. diff infection, call your doctor or health care team right away so you can start treatment as soon as possible.