Rifaximin is an antibiotic that has revolutionised the treatment of certain gastrointestinal (GI) disorders.

It is primarily used for treating conditions like traveller’s diarrhoea, irritable bowel syndrome with diarrhoea (IBS-D), and hepatic encephalopathy.

Curious to know more about Rifaximin and its antibacterial properties?

In this blog, Karetrip will explore the unique properties of Rifaximin, its uses, and its mechanism of action, along with some important considerations for its use.

What is Rifaximin?

Rifaximin is a semi-synthetic antibiotic derived from rifamycin, a compound originally isolated from bacteria in soil samples.

Developed in Italy in the late 1980s, it became widely used due to its effectiveness against a range of bacteria that cause GI disorders. Unlike broad-spectrum antibiotics that affect a wide range of bacterial species, Rifaximin targets specific bacteria in the gut, making it ideal for treating gastrointestinal infections without causing widespread changes in the microbiome.

It’s available in tablet form and is often prescribed in specific treatment courses depending on the condition being treated.

How Does Rifaximin Work?

Rifaximin works by inhibiting bacterial RNA synthesis. It binds to the beta subunit of bacterial DNA-dependent RNA polymerase, an enzyme necessary for bacterial RNA synthesis.

By blocking this enzyme, Rifaximin prevents the production of proteins essential for bacterial growth and survival, effectively killing or inhibiting the growth of bacteria. Since it is minimally absorbed in the intestines (with less than 1% entering the bloodstream), Rifaximin’s effects remain localised within the gut.

This localised activity helps reduce systemic exposure and limits the potential for common antibiotic-related side effects, such as secondary infections or adverse effects on organs.

Uses of Rifaximin

1. Traveler’s Diarrhoea

Traveler’s diarrhoea is a common issue for individuals travelling to regions with different bacterial profiles in the water and food. Caused primarily by strains of Escherichia coli (E. coli), traveller’s diarrhoea can be disruptive and uncomfortable.

Rifaximin is effective for treating this condition due to its action against E. coli and other diarrhoea-causing bacteria. Unlike systemic antibiotics, it targets the intestines directly, providing quick relief without impacting bacteria in other parts of the body.

Typically, a short course of Rifaximin is sufficient to resolve symptoms, making it a popular option for travellers.

2. Irritable Bowel Syndrome with Diarrhoea (IBS-D)

IBS-D is a subtype of irritable bowel syndrome characterised by chronic abdominal pain, bloating, and frequent diarrhoea.

While the exact cause of IBS-D is unknown, bacterial overgrowth in the intestines is believed to play a significant role in its symptoms. Rifaximin is one of the few antibiotics approved for IBS-D because it reduces bacterial overgrowth in the intestines without significant side effects.

Patients who complete a course of Rifaximin often report relief from bloating, abdominal discomfort, and diarrhoea, with some experiencing lasting benefits even after discontinuing the medication.

3. Hepatic Encephalopathy

Hepatic encephalopathy is a condition that occurs in people with advanced liver disease, where toxins like ammonia build up in the bloodstream due to liver dysfunction.

These toxins can reach the brain, causing confusion, memory problems, and even coma in severe cases. Rifaximin helps manage hepatic encephalopathy by reducing the production of ammonia-producing bacteria in the intestines.

When used alongside lactulose, another medication that helps remove ammonia from the gut, Rifaximin can significantly reduce episodes of hepatic encephalopathy and improve the quality of life for individuals with liver disease.

4. Small Intestinal Bacterial Overgrowth (SIBO)

SIBO is a condition where excessive bacteria grow in the small intestine, leading to symptoms like bloating, gas, abdominal pain, and diarrhoea.

Though Rifaximin is not officially approved for SIBO, it is often prescribed off-label due to its efficacy in reducing bacterial overgrowth in the small intestine.

Rifaximin’s minimal absorption into the bloodstream makes it particularly suitable for SIBO, as it acts directly within the small intestine without causing systemic side effects.

5. Clostridium difficile Infection (C. diff)

While not a first-line treatment, Rifaximin is sometimes used to manage recurrent Clostridium difficile infections. C. difficile is a bacterial infection that can cause severe diarrhoea and colitis, often as a result of prolonged antibiotic use.

Following an initial treatment with other antibiotics, Rifaximin may be used as a secondary measure to help prevent recurrence by targeting any remaining C. difficile bacteria in the gut.

Antibacterial Properties of Rifaximin

• Rifaximin has a broad spectrum of action against both Gram-positive and Gram-negative bacteria, though it is particularly effective against GI pathogens such as E. coli, Salmonella, and Shigella.

• Due to its low absorption in the intestines, Rifaximin remains concentrated within the gastrointestinal tract, allowing it to target harmful bacteria effectively without affecting bacteria elsewhere in the body.

• This feature also makes Rifaximin less likely to contribute to antibiotic resistance—a major concern in modern medicine—as its localised effect minimises the exposure of other bacteria to the drug.

• Another unique property of Rifaximin is its ability to work as a "gut-specific" antibiotic. Unlike traditional antibiotics, which can disrupt the balance of bacteria in various parts of the body, Rifaximin focuses on the GI tract.

• This selective activity helps to preserve the normal gut microbiome, as it doesn’t harm beneficial bacteria that reside outside the intestine. Additionally, Rifaximin’s action is bactericidal—it kills bacteria outright rather than merely inhibiting their growth, which leads to faster symptom relief for patients.

Side Effects and Precautions

Although Rifaximin is generally well-tolerated, some side effects may occur, including

• Nausea

• Bloating

• Dizziness

• Headache

• Abdominal Pain

Severe side effects are rare but may include allergic reactions or severe diarrhoea. If symptoms worsen, patients should seek medical attention promptly.

Patients with liver disease, kidney impairment, or a history of antibiotic allergies should exercise caution when using Rifaximin. Additionally, Rifaximin should not be used to treat systemic infections, as its low absorption rate limits its effectiveness outside of the GI tract.

While Rifaximin has shown effectiveness in treating specific GI conditions, patients are encouraged to use it only under medical supervision, as overuse or misuse may reduce its efficacy.

Rifaximin and Antibiotic Resistance

One of the primary concerns with antibiotics is the development of resistance, where bacteria evolve to survive despite treatment. However, Rifaximin’s unique properties help mitigate this risk.

Since it remains in the intestines, the bacteria exposed to Rifaximin are primarily gut-specific, minimising the risk of resistance in other parts of the body. Furthermore, Rifaximin has a low rate of resistance development compared to other antibiotics, making it a relatively safe option for treating chronic or recurrent GI issues.

Nonetheless, responsible use is essential, as overuse or misuse of any antibiotic can still contribute to resistance.

The information provided represents the views and opinions of Karetrip. It is crucial to conduct your own independent research before making any decisions regarding your healthcare journey.