Pseudomembranous colitis is a severe inflammation of the lining of the large intestine (colon). Ironically, this condition is most often a side effect of taking antibiotics prescribed to treat a different infection. These medications can disrupt the balance of healthy bacteria in the gut, allowing a harmful bacterium called Clostridioides difficile (formerly Clostridium difficile or C. diff) to overgrow and release toxins. The resulting symptoms of intense diarrhea, abdominal cramps, and fever can be physically exhausting and disruptive to daily life.

Treatment is urgent and essential. Without intervention, the inflammation can lead to life-threatening complications, such as a hole in the bowel or severe dehydration. The primary goal of treatment is to stop the bacterial overgrowth, neutralize the toxins damaging the colon, and restore the natural bacterial balance. Because the severity of the infection ranges from mild discomfort to critical illness, treatment plans are tailored to the individual’s condition and risk factors (Mayo Clinic, 2023).

Overview of treatment options for Pseudomembranous Colitis

The first step in treating pseudomembranous colitis is almost always stopping the antibiotic that triggered the infection, if medically feasible. In mild cases, this alone may allow symptoms to resolve as the gut bacteria return to normal. However, most patients require specific medical treatment to eradicate the C. diff bacteria.

The standard approach involves the use of specialized antibiotics that target C. diff without further harming the beneficial gut flora. For patients who experience recurrent infections, a common challenge with this condition, treatment strategies may shift to include newer biological drugs or procedures like fecal microbiota transplantation (FMT) to restore gut health. However, medication remains the foundation of acute management.

Medications used for Pseudomembranous Colitis

Physicians rely on a select group of antibiotics to treat this condition. Unlike the antibiotics that caused the problem, these drugs are specifically effective against anaerobic bacteria like C. diff.

The current first-line treatments are fidaxomicin and vancomycin. Fidaxomicin is often preferred because it specifically targets C. diff with minimal impact on other gut bacteria, which helps prevent the infection from coming back. Vancomycin is also a standard, highly effective option, typically taken orally so it can reach the colon directly.

For situations where these drugs are unavailable or for very mild cases, metronidazole may be used, though it is generally considered a second-line option due to lower cure rates.

For patients at high risk of recurrence, doctors may prescribe a biologic medication called bezlotoxumab. This is not an antibiotic but a monoclonal antibody given as a one-time intravenous infusion alongside antibiotic treatment. Clinical experience suggests that patients typically see an improvement in diarrhea and cramping within 2 to 4 days of starting antibiotic therapy (American College of Gastroenterology, 2021).

How these medications work

Antibiotics like fidaxomicin and vancomycin work by inhibiting the growth and reproduction of the C. diff bacteria. When taken orally, these drugs are not absorbed well into the bloodstream; instead, they stay in the digestive tract. This allows them to arrive at the site of infection in high concentrations, attacking the bacteria directly where they are causing damage.

Bezlotoxumab works through a different mechanism. It does not kill bacteria. Instead, it binds to and neutralizes Toxin B, one of the harmful substances released by C. diff that destroys the colon lining. By blocking this toxin, the medication protects the gut wall and reduces the likelihood that the inflammation will flare up again after the antibiotics are finished (National Library of Medicine, 2022).

Side effects and safety considerations

Because oral vancomycin and fidaxomicin are poorly absorbed by the body, they cause fewer systemic side effects than many other antibiotics.Common complaints include nausea, abdominal pain, or a bad taste. Metronidazole can cause a metallic taste and severe nausea, and requires strict alcohol avoidance.

Safety is key, especially for vulnerable elderly patients. Bezlotoxumab needs monitoring for heart failure in those with cardiac history. Complete the full medication course, even with symptom improvement, to prevent bacterial regrowth. Seek immediate care for severe abdominal swelling, bloody stool, confusion, or rapid heart rate (signs of dehydration).

Since everyone’s experience with the condition and its treatments can vary, working closely with a qualified healthcare provider helps ensure safe and effective care.

References

1. American College of Gastroenterology. https://gi.org
2. Mayo Clinic. https://www.mayoclinic.org
3. National Library of Medicine. https://pubmed.ncbi.nlm.nih.gov
4. Centers for Disease Control and Prevention. https://www.cdc.gov