Xifaxan Is a Gut-Targeted Antibiotic Used for Hepatic Encephalopathy, IBS-D, and Travelers' Diarrhea

Xifaxan (Rifaximin) is a prescription antibiotic that works almost entirely inside your digestive tract to reduce harmful bacteria. It's one of the most widely prescribed gut-specific antibiotics in the U.S. — but its high price tag and insurance requirements mean many patients have questions before starting it. Here's everything you need to know about Xifaxan in 2026.

What Is Xifaxan?

Xifaxan is the brand name for Rifaximin, a rifamycin-class antibiotic. It's manufactured by Salix Pharmaceuticals, a division of Bausch Health. Unlike most antibiotics that absorb into your bloodstream and work throughout your body, Xifaxan is designed to stay in your gut — less than 0.4% of each dose is absorbed systemically. This localized action is what makes it effective for GI-specific conditions while causing fewer body-wide side effects.

Xifaxan is not a controlled substance and is available in two tablet strengths: 200 mg and 550 mg.

What Is Xifaxan Used For?

Xifaxan is FDA-approved for three conditions:

1. Hepatic Encephalopathy (HE)

Xifaxan 550 mg is approved to reduce the risk of overt hepatic encephalopathy recurrence in adults. HE is a complication of liver disease where toxins (especially ammonia) build up in the blood and affect brain function, causing confusion, disorientation, and in severe cases, coma. Xifaxan reduces the gut bacteria that produce these toxins. It's often used alongside Lactulose as a long-term maintenance therapy.

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

Xifaxan 550 mg is approved for IBS-D in adults. It's typically prescribed as a 14-day course and can be repeated up to two additional times if symptoms return. Xifaxan works in IBS-D by reducing the overgrowth of bacteria in the gut that may contribute to bloating, abdominal pain, and diarrhea.

3. Travelers' Diarrhea

Xifaxan 200 mg is approved for travelers' diarrhea caused by noninvasive strains of E. coli in patients 12 years and older. The course is shorter — 200 mg three times daily for 3 days.

Off-Label Uses

Doctors also prescribe Xifaxan off-label for:

• Small intestinal bacterial overgrowth (SIBO)
• Diverticular disease
• Inflammatory bowel disease (as an adjunct)
• Recurrent Clostridioides difficile infection (alongside Vancomycin)

How Is Xifaxan Taken?

Xifaxan is taken by mouth and can be taken with or without food. Swallow the tablets whole. Here's how dosing breaks down by condition:

• Hepatic encephalopathy: 550 mg twice daily, taken continuously as long as your doctor prescribes it.
• IBS-D: 550 mg three times daily for 14 days. If symptoms recur, your doctor may prescribe up to two additional 14-day courses.
• Travelers' diarrhea: 200 mg three times daily for 3 days. Complete the full course even if you start feeling better.

Always take Xifaxan exactly as prescribed. Don't stop early, skip doses, or double up if you miss one. For HE patients, stopping Xifaxan can lead to a recurrence of encephalopathy symptoms.

Who Should Not Take Xifaxan?

Xifaxan is contraindicated in people with a known hypersensitivity to Rifaximin, any rifamycin antibiotic, or any component of the product. If you've ever had an allergic reaction to Rifampin (Rifadin) or other rifamycin antibiotics, tell your doctor before starting Xifaxan.

Additional cautions:

• Severe liver impairment (Child-Pugh C): Patients with severe liver disease may absorb more Rifaximin systemically, increasing the risk of side effects. Close monitoring is recommended.
• Pregnancy: Xifaxan is Pregnancy Category C. Use only if the potential benefit justifies the risk.
• Children under 12: Not approved for travelers' diarrhea in children under 12. Not approved for IBS-D or HE in patients under 18.

For a full list of side effects, read our Xifaxan side effects guide. For drug interactions, see Xifaxan drug interactions.

How Much Does Xifaxan Cost?

Xifaxan is expensive. Without insurance, expect to pay $1,600 to $2,200 for a 30-day supply of the 550 mg tablets (60 tablets). There is no generic version of Xifaxan available in the United States as of 2026.

Here's how to manage the cost:

• Insurance: Xifaxan is typically covered by commercial insurance and Medicare Part D, but often requires prior authorization. It's usually placed on Tier 3 or specialty tier formularies. Some plans require step therapy through Lactulose (for HE) before approving Xifaxan.
• Manufacturer copay card: The Xifaxan Instant Copay Savings Card can bring your copay to as little as $0 with eligible commercial insurance. Visit xifaxan.copaysavingsprogram.com or call 1-866-XIFAXAN.
• Patient assistance: The Bausch Health Patient Assistance Program helps uninsured or underinsured patients. The Patient Access Network (PAN) Foundation may also offer help.

For a complete breakdown of savings options, see our guide to saving money on Xifaxan.

Final Thoughts

Xifaxan is a unique antibiotic — it treats conditions in your gut without significantly entering your bloodstream, which means fewer systemic side effects and targeted relief for conditions like hepatic encephalopathy, IBS-D, and travelers' diarrhea. The biggest barrier for most patients is cost, not the medication itself. Work with your doctor and insurance to get prior authorization squared away, use the manufacturer copay card if eligible, and check Medfinder to find a pharmacy that stocks it near you.