Xifaxan (Rifaximin)

Xifaxan is the brand name for rifaximin, a rifamycin-derived antibiotic that is minimally absorbed when taken by mouth. Because most of the drug stays in the intestinal tract, it primarily acts “locally” in the gut rather than circulating throughout the body [1].

In cirrhosis, rifaximin is most commonly used to prevent recurrent overt hepatic encephalopathy (episodes of confusion, disorientation, sleep–wake reversal, impaired coordination, or decreased alertness) [2] [3].

Rifaximin is commonly prescribed after a patient has had overt HE, particularly if HE recurs despite lactulose or if maintaining remission has been difficult. Major evidence supporting rifaximin in this setting comes from a randomized, placebo-controlled trial demonstrating improved maintenance of HE remission and fewer HE-related hospitalizations [1].

Clinical practice guidelines endorsed by major liver societies recommend rifaximin as an add-on to lactulose for prevention of recurrent HE after the second episode [2].

Hepatic encephalopathy is a spectrum of potentially reversible neuropsychiatric abnormalities that can occur with advanced liver dysfunction. It ranges from subtle cognitive changes to severe confusion, somnolence, and coma [3].

While HE is multifactorial, gut-derived toxins (including ammonia and other nitrogenous compounds) and systemic inflammation are central themes. Treatments therefore focus on reducing toxin production/absorption and addressing triggers (infection, GI bleeding, constipation, dehydration, sedatives) [2] [3].

• Rifaximin’s role: reduce intestinal bacterial products implicated in HE and help maintain remission [1].
• Guideline positioning: commonly recommended as add-on therapy to lactulose for recurrent HE [2].

Rifaximin is considered a “gut-selective” antibiotic because absorption is low, leading to relatively few systemic adverse effects. Its beneficial impact in HE is thought to involve both antimicrobial and non-antimicrobial (anti-inflammatory/metabolic) mechanisms [1] [4].

• Alters gut microbial function: associated with changes in microbial metabolism and endotoxemia markers in cirrhosis [4].
• Supports HE remission: demonstrated clinical benefit in maintaining remission in overt HE [1].
• Often complements lactulose: targets toxin generation, while lactulose promotes toxin removal via catharsis/acidification [2].

A commonly used regimen for prevention of recurrent overt HE is rifaximin 550 mg by mouth twice daily [1].

In practice, rifaximin is typically taken consistently every day (not “as needed”), including on days when symptoms are controlled, because the goal is to prevent recurrence rather than treat a single episode [2].

Many clinicians continue therapy long-term once it is clearly effective, especially in patients with recurrent HE [2]. Any change (including stopping) should be directed by your hepatology/transplant team.

• Fewer recurrent HE episodes while maintaining remission compared with placebo in a major randomized trial [1].
• Reduced HE-related hospitalizations in the same trial population [1].
• Guideline-supported add-on strategy to lactulose for prevention of recurrence after multiple episodes [2].
• Often well tolerated due to minimal systemic absorption (though no medication is risk-free) [3].

Most patients tolerate rifaximin well. Because absorption is low, systemic adverse effects are generally less common than with many oral antibiotics [3].

Potential side effects can include:

• GI symptoms (nausea, abdominal discomfort)
• Headache
• Fatigue

Important practical point: if confusion is worsening, do not assume it is “just HE.” Infections, GI bleeding, dehydration, electrolyte abnormalities, constipation, and sedating medications can precipitate or mimic HE and may require urgent evaluation [2] [3].

In routine cirrhosis care, rifaximin is commonly used with lactulose, not instead of it. Guidelines specifically recommend rifaximin as an add-on to lactulose for prevention of recurrent HE after the second episode [2].

• Lactulose: reduces absorption of nitrogenous compounds and promotes elimination via bowel movements [2].
• Rifaximin: modulates gut microbial activity and is associated with maintenance of HE remission [1].

If lactulose side effects (bloating/diarrhea) are significant, your team may adjust lactulose dosing—but do not change doses on your own without a plan.

Taking rifaximin does not reduce transplant eligibility. In many patients, preventing recurrent HE helps maintain:

• Safety at home: fewer episodes of impaired judgment and falls
• Consistency with evaluation: clearer cognition for appointments and testing
• Stability while waiting: fewer HE-related hospitalizations (which can delay or complicate evaluation)

Because HE can fluctuate, transplant teams often pay close attention to adherence with HE therapies and to trigger management [2].

Xifaxan is often expensive, and many insurers require prior authorization. Liver and transplant clinics are accustomed to submitting documentation showing recurrent HE and guideline-supported use [2].

Common ways patients obtain access include:

• Insurance prior authorization and step-therapy documentation
• Manufacturer copay support (when eligible)
• Patient-assistance programs and foundations (clinic social work/pharmacy teams often help)

If cost is a barrier, notify your team early—abrupt interruption can be followed by HE recurrence in vulnerable patients.

• Do I meet criteria for rifaximin as add-on therapy for recurrent HE? [2]
• What is my target lactulose plan (e.g., bowel movement goal) while on rifaximin? [2]
• If I miss a dose, what should I do (and when should I call you)?
• What triggers should I watch for (constipation, infection, GI bleeding, dehydration, sedatives)? [3]
• What are the fastest warning signs that should prompt urgent evaluation (worsening confusion, somnolence, inability to stay awake, falls)? [3]
• What assistance options exist if my copay is unaffordable?