Rifaximin
Rifaximin is an antibiotic that works mainly in the gut, used to treat travelers' diarrhea, irritable bowel syndrome with diarrhea (IBS-D), and to reduce the risk of recurring hepatic encephalopathy (a brain condition caused by liver disease).
🧬 Where this information comes from Click to expand
The clinical label records used on this page are FDA-filed Structured Product Labeling (SPL) retrieved through openFDA. We identified 3 clinical label sets within the page’s selected clinical scope after exact ingredient or ingredient-combination matching and applicable route/form matching. Forms, routes, brands, labelers, strengths, and NDC product-record counts are built separately from matching FDA National Drug Code Directory records. The linked DailyMed document is a representative official source for verification, not the page’s only clinical source. View the linked label on DailyMed →
📖 Rifaximin: Patient Information Guide
A plain-language walkthrough of Rifaximin — what it treats, how it works, how it’s taken, side effects, warnings and interactions. Tap any section to expand it.
🎯What it's used for▾
Rifaximin is an antibiotic that works in the gut and is available as Xifaxan tablets. It is approved for three distinct uses:
- Travelers' diarrhea: Xifaxan treats diarrhea caused by noninvasive strains of Escherichia coli in adults and children 12 years and older. It should not be used if diarrhea is accompanied by fever or blood in the stool, or if a different bacteria is suspected.
- Hepatic encephalopathy (HE) prevention: Xifaxan reduces the risk of HE — episodes of confusion, disorientation, and other brain symptoms caused by liver disease — coming back in adults. Most patients in clinical trials also used lactulose alongside Xifaxan.
- Irritable bowel syndrome with diarrhea (IBS-D): Xifaxan is approved to treat IBS-D in adults. Patients who have a relapse of symptoms can be retreated up to two additional times.
⚙️How it works▾
Rifaximin is an antibacterial drug that targets bacteria directly inside the intestines. Unlike most antibiotics, it is poorly absorbed into the bloodstream — it stays concentrated in the gut, where it works against the bacteria causing the problem. This local action is why it is effective for gut-based conditions but cannot be used to treat infections in other parts of the body.
Because it is an antibiotic, using rifaximin when it isn't needed — or for infections it can't treat — can contribute to antibiotic resistance, making bacteria harder to treat in the future. It should only be used when a bacterial cause is confirmed or strongly suspected.
💊How it's taken▾
Xifaxan tablets are taken by mouth and can be taken with or without food, making it flexible to fit your routine. The course length and frequency depend on what it's being used for — travelers' diarrhea is a short 3-day course taken three times a day; IBS-D is a 14-day course taken three times a day (with up to two repeat courses if symptoms come back); and for hepatic encephalopathy, it is taken twice a day as an ongoing preventive regimen. Always follow your prescriber's exact instructions — do not stop early or adjust the schedule on your own.
🤒Side effects — in detail▾
The most commonly reported side effects vary by condition being treated:
- Travelers' diarrhea use: headache
- Hepatic encephalopathy use: swelling in the legs or feet (peripheral edema), nausea, dizziness, fatigue, constipation, urinary tract infection, trouble sleeping (insomnia), anemia (low red blood cells), itching, and fluid in the abdomen (ascites)
- IBS-D use: nausea, elevated liver enzyme (ALT) on blood tests
Rarely, serious reactions can occur: severe allergic reactions (swelling of the face or tongue, anaphylaxis), a dangerous gut infection called C. difficile-associated diarrhea, and severe skin reactions such as Stevens-Johnson syndrome — especially in people with cirrhosis. Seek medical attention immediately for any of these.
⚠️Warnings & precautions▾
- Not effective for all travelers' diarrhea: Rifaximin only works against E. coli-caused travelers' diarrhea. If your symptoms include fever, blood in the stool, or don't improve within 24–48 hours, stop taking it and contact your doctor — a different antibiotic may be needed.
- C. difficile-associated diarrhea: Like any antibiotic, rifaximin can disrupt normal gut bacteria and trigger a serious infection called C. difficile colitis. This can happen even weeks after finishing the medication. Tell your doctor about any new or worsening diarrhea after treatment.
- Severe liver disease: People with severe hepatic impairment (Child-Pugh Class C) have significantly higher drug levels in their blood. Use with caution under close medical supervision.
- Serious skin reactions: Rare but severe skin reactions — including Stevens-Johnson syndrome and toxic epidermal necrolysis — have been reported, mainly in people with cirrhosis. Stop the medication and get medical help immediately at the first sign of blistering, peeling, or widespread rash.
- Antibiotic resistance: Using this medication unnecessarily increases the risk of creating drug-resistant bacteria.
🔀What it interacts with▾
Rifaximin has a few clinically important drug interactions to be aware of:
- Cyclosporine (Sandimmune, Neoral): This immune-suppressing drug is a P-glycoprotein inhibitor, and taking it with rifaximin can significantly raise rifaximin levels in the blood. Use together only if necessary and under careful medical supervision — especially in people with liver disease, where levels can be even higher.
- Warfarin (Coumadin): Rifaximin may affect warfarin's blood-thinning effect. Your INR (a measure of how well your blood clots) should be monitored, and your warfarin dose may need adjustment.
- CYP3A4 medications: Rifaximin may affect how the liver processes certain other medications in people with reduced liver function. Tell your prescriber and pharmacist about every medication, supplement, and herbal product you take.
This is not a complete list of interactions. Always talk with your doctor or pharmacist before starting, stopping, or changing any medication.
📋Before taking it▾
- Allergy: Do not take rifaximin if you have ever had a hypersensitivity reaction to rifaximin, any rifamycin antibiotic (such as rifampin or rifabutin), or any ingredient in Xifaxan.
- Pregnancy: Animal studies showed birth defects at certain doses. There is no human safety data. Discuss the risks with your doctor before taking this medication if you are pregnant or could become pregnant.
- Breastfeeding: It is not known whether rifaximin passes into human breast milk. Talk to your doctor about the benefits and risks before breastfeeding while on this medication.
- Children: Xifaxan is not approved for travelers' diarrhea in children under 12, or for IBS-D or hepatic encephalopathy in patients under 18.
- Severe liver disease: Rifaximin blood levels are much higher in people with severe liver impairment. Use with caution and tell your doctor about your liver condition.
- Older adults: No major differences in safety or effectiveness were found between older and younger adults in IBS-D and HE studies, but individual sensitivity may vary.
- Kidney disease: The effects of kidney impairment on rifaximin have not been studied — let your prescriber know if you have kidney problems.
🚑If you take too much▾
If more than the prescribed amount of rifaximin is taken, stop the medication and contact your doctor or a poison control center right away. In clinical studies where higher doses were used, the side effects seen were similar to those of placebo — no unique overdose symptoms were identified. Treatment would focus on managing any symptoms that appear and providing supportive care.
🔬Pharmacokinetics — how your body processes it▾
Rifaximin is taken by mouth and reaches peak levels in the blood within about an hour, though very little actually gets absorbed — the vast majority stays in the gut. This limited absorption is intentional: it keeps the drug concentrated where it's needed (the intestines) and minimizes effects on the rest of the body. The drug is mainly broken down by a liver enzyme called CYP3A4 and is excreted almost entirely in the stool, mostly unchanged.
In people with liver disease — particularly those with hepatic encephalopathy — blood levels of rifaximin can be significantly higher than in healthy individuals, because the liver isn't clearing it as efficiently. A high-fat meal can increase overall absorption, but this doesn't meaningfully change how the drug performs clinically. The drug's half-life (the time it takes for half the drug to leave the body) is roughly 5–6 hours in healthy adults.
📦How to store it▾
Store XIFAXAN Tablets at 20° to 25°C (68° to 77°F); excursions permitted to 15° to 30°C (59° to 86°F) .
📄 Written from Rifaximin’s FDA-approved label information, summarized in plain language with AI, and reviewed by our pharmacy team before publication. Every point is grounded in that labeling — nothing is invented. How we use AI →
Supplements & herbs that interact with Rifaximin
44 supplements and herbal products have documented interactions with Rifaximin in the licensed clinical database we use. Most are manageable — but your pharmacist should know about everything you take, including vitamins and herbals.
- Major · 1
- Moderate · 33
- Minor · 10
Educational information from a licensed clinical database (Natural Medicines) — see our data sources & update cadence. Not medical advice: an interaction being documented does not mean it will happen to you; do not start or stop medications or supplements without professional guidance.
Nutrient depletion considerations
Rifaximin has been associated with lower levels of 7 nutrients in the clinical literature. This does not mean a deficiency will occur — it means these may be worth discussing with your pharmacist or healthcare provider, especially with long-term use.
- Higher significance · 6
- Moderate · 1
Educational information from a licensed clinical database (Natural Medicines) — not medical advice. Do not start or stop medications or supplements without professional guidance.
🩺 Pharmacist Counseling Corner
Quick, plain-English answers to the questions patients ask most about Rifaximin — the kind of thing our pharmacy team would talk through with you at the counter.
What exactly is Xifaxan used for? ▾
Can I take Xifaxan with food, and does it matter when I take it? ▾
My travelers' diarrhea doesn't seem to be getting better — should I keep taking it? ▾
Are there any medications I need to be careful about taking with Xifaxan? ▾
Is it safe to take Xifaxan if I'm pregnant or breastfeeding? ▾
What side effects should I watch out for, and which ones need a doctor call? ▾
Is Rifaximin available over the counter? ▾
When was Rifaximin first available? ▾
Who makes Rifaximin? ▾
💬 Answers drafted from Rifaximin’s FDA-approved label information, summarized in plain language with AI, and reviewed by our pharmacy team before publication. Grounded in that labeling — nothing is made up. How we use AI →
🧰 Keep exploring
💊 How Rifaximin comes
Rifaximin is available in 1 form. Different forms and brands can have different approved uses, doses, schedules, and directions. Follow the instructions for your exact product, and do not switch forms without guidance from your prescriber or pharmacist.
Tablet
How this form is used
- Xifaxan is used to treat travelers' diarrhea caused by E. coli in adults and children 12 and older
- Xifaxan is used to reduce the risk of hepatic encephalopathy recurrence in adults
- Xifaxan is used to treat irritable bowel syndrome with diarrhea (IBS-D) in adults
- Xifaxan tablets are taken by mouth with or without food
- For travelers' diarrhea, Xifaxan is taken three times a day for 3 days
- For hepatic encephalopathy, Xifaxan is taken two times a day as an ongoing regimen
- For IBS-D, Xifaxan is taken three times a day for 14 days; patients who relapse may be retreated up to two more times with the same course
📊 Rifaximin across the U.S. market
How Rifaximin appears in the FDA’s National Drug Code Directory — including its dosage forms, strengths, brand names, manufacturers, and FDA-listed product records. These are directory records, not sales or prescription volume.
Also listed with the FDA, not a patient dose form: Powder (18) — bulk drug substance sold to compounders/manufacturers and multi-item kits. These aren’t counted in the dose-form total above.
Share of FDA-listed product records by manufacturer — FDA National Drug Code Directory. Record counts are not sales or prescription volume.
📈 How widely Rifaximin is used
A general measure of how commonly Rifaximin is prescribed, based on Medicaid — one of the largest public drug programs. The figure below is prescriptions filled in Q1–Q4 2025, summed across every form and brand of the drug.
Think of this as a proxy for how widely Rifaximin is used, drawn from freely available public data. Medicaid is just one program — these numbers don’t include Medicare, other government coverage, or commercial and cash-pay prescriptions, so real-world use is higher than what’s shown here.
How commonly is Rifaximin prescribed? Of the 1,596 medications we measure, Rifaximin ranks #487 by Medicaid prescriptions — more than 69% of them.
Utilization by Rifaximin product
Pick a product to see its own Medicaid numbers. Each chip is one clinical product — a specific strength & dosage form as defined by RxNorm — with brand-name and generic versions combined.
rifaximin 550 MG Oral Tablet Most dispensed
Summed across the 2 of 8 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 856664
rifaximin 200 MG Oral Tablet
Summed across the 1 of 4 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 429662
Shares are of the Medicaid prescriptions shown here. Product grouping follows RxNorm (the National Library of Medicine’s drug terminology), so “one product” means one strength & dosage form regardless of manufacturer. Dollar figures are gross Medicaid reimbursement before mandatory rebates — rebates (often large, especially for brand-name drugs) are confidential, so actual net cost to Medicaid is lower than shown.
Source: Medicaid State Drug Utilization Data (CMS), aggregated by generic ingredient — summed across every NDC (all brands, strengths, salt forms and dosage forms) of Rifaximin, and across all states and both fee-for-service and managed-care claims. A general popularity signal; it excludes Medicare, commercial insurance and cash prescriptions, so it is not total U.S. use. Based on the 3 of 12 listed Rifaximin NDCs with Medicaid activity.
🔍 Compare Rifaximin products
A representative set of FDA-listed product records for Rifaximin — across manufacturers, strengths, and dosage forms, grouped by form with each product’s manufacturer and how the FDA approved it. The same medicine may be made and packaged by different companies, so a single drug can have many directory entries. (It’s also why a refill can look different — a new shape, color, or box — even though it contains the same medication.)
| Strength | Route | Manufacturer / Labeler | Category ⓘ | Details |
|---|---|---|---|---|
| 💊Tablet | ||||
| 200 mg | Oral | A-S Medication Solutions × 2 listings | NDA | View NDC → |
| 550 mg | — | Alfasigma SpA | DRUG FOR FURTHER PROCESSING | View NDC → |
| 550 mg | — | Bausch Health Companies Inc. | DRUG FOR FURTHER PROCESSING | View NDC → |
| 550 mg | Oral | Cardinal Health | NDA | View NDC → |
| 550 mg | Oral | Cardinal Health 107, LLC × 2 listings | NDA | View NDC → |
| 200 mg | Oral | Salix Pharmaceuticals, Inc. × 3 listings | NDA | View NDC → |
| 550 mg | Oral | Salix Pharmaceuticals, Inc. × 3 listings | NDA | View NDC → |
| 💊Bulk drug substance | ||||
| 50 kg/50 kg | — | Aurobindo Pharma Limited | BULK INGREDIENT | View NDC → |
| 1 g/g | — | AX Pharmaceutical Corp | BULK INGREDIENT FOR HUMAN PRESCRIPTION COMPOUNDING | View NDC → |
| 1 kg/kg | — | Cambrex Profarmaco Milano S.r.l. | BULK INGREDIENT | View NDC → |
| 1 kg/kg | — | Chemeca Drugs Private Limited | BULK INGREDIENT FOR HUMAN PRESCRIPTION COMPOUNDING | View NDC → |
| 25 kg/25 kg | — | Clarochem Ireland Ltd. | BULK INGREDIENT | View NDC → |
| 1 kg/kg | — | Granules India Limited × 2 listings | BULK INGREDIENT | View NDC → |
| 1 kg/kg | — | Hetero Drugs Limited | BULK INGREDIENT | View NDC → |
| 1 kg/kg | — | Lupin Limited | BULK INGREDIENT | View NDC → |
| 1 g/g | — | Medisca Inc. | BULK INGREDIENT | View NDC → |
| 1 kg/kg | — | MSN Laboratories Private Limited × 2 listings | BULK INGREDIENT | View NDC → |
| 1 kg/kg | — | Olon SpA × 3 listings | BULK INGREDIENT | View NDC → |
| 1 kg/kg | — | Optimus Drugs Private Limited | BULK INGREDIENT | View NDC → |
| 25 kg/25 kg | — | Sun Pharmaceutical Industries, Inc. | BULK INGREDIENT | View NDC → |
| 1 kg/kg | — | Willow Birch Pharma, Inc. | BULK INGREDIENT | View NDC → |
Showing 31 of 31 products — FDA National Drug Code Directory. See every product, package size and price: browse all 31 Rifaximin NDCs →
📈 What people report — real-world data (FDA FAERS)
After a medicine reaches the market, patients, doctors and drugmakers can send the FDA reports of problems they think may be linked to it. Here’s what’s been reported for Rifaximin — a signal of what to watch for, not proof the drug caused it.
Source: openFDA, from the FDA Adverse Event Reporting System (FAERS). These are voluntary reports — they don’t prove the drug caused the effect, and counts reflect how often something was reported, not how often it actually happens. Reports also often name the very problem the medicine is taken for — a common reason to file one is that the drug didn’t help — so for a pain reliever you may see “pain” high on the list; that points to why the report was filed, not to the drug causing the symptom. This counts every report that lists Rifaximin in any role, so the total runs higher than the FDA’s official dashboard, which counts only cases where the drug is the suspect. For the authoritative figures, see the FDA FAERS Public Dashboard. Always talk to your pharmacist or doctor.
🏛️ The road to your pharmacy
How Rifaximin went from FDA review to the pharmacy shelf — the key milestones in its regulatory journey.
Source: Drugs@FDA.
🚨 Recall history
A recall is when a specific batch of a medicine is pulled from the market — usually a manufacturing issue, not a problem with the drug itself. Class I is most serious, Class III least.
Source: openFDA drug enforcement (recall) reports.
RxNorm Concept Web — From Ingredient to Every Form and Strength
This page starts with one ingredient concept (IN). The branches below show its dose-form concepts (SCDF), then the available clinical drug and strength concepts (SCD). Combination products remain separate concepts with their own pages.
RxCUI 35619 1 dose form · 2 strengths
-
Dose form (SCDF) Oral Tablet RxCUI 451309In current FDA listings
Look up RxCUI 35619 in the RxCUI Atlas →
RxNorm is the U.S. National Library of Medicine’s normalized drug vocabulary. Its concept hierarchy can include forms that are not currently marketed; the status on each branch compares that concept with current FDA listings. RxCUIs identify vocabulary concepts, not individual packages or manufacturers.
📦 Supply & shortage status
Whether Rifaximin is in short supply in the U.S. right now, plus any shortage history the FDA has on record. A shortage usually reflects a manufacturing or demand issue — not a safety problem with the drug.
Source: openFDA, from the FDA Drug Shortages database.
🏷️ Sold under these brand names
🏭 Manufacturers & labelers
RxNorm drug class
Rifaximin belongs to the Rifamycin Antibacterial class.
Classified by RxNorm RxClass — the U.S. National Library of Medicine's standardized drug-classification service (Established Pharmacologic Class from the FDA, the ATC drug family from the WHO, and mechanism of action). Reference only, not medical advice.
🔬 Where this comes from
Core label, product, RxNorm, safety, and utilization data on this page come from the sources identified below. AI-written, editorial, and licensed sections are labeled separately.
How we combine label and product data
HelloPharmacist combines public FDA and NLM records; we don’t author the underlying clinical facts. We identified 3 FDA-filed SPL label sets within the page’s selected clinical scope after exact ingredient or ingredient-combination matching and applicable route/form matching. The representative label is the starting point for the displayed reference monograph; the 12 largest stored in-scope SPL records, which may include that representative, are compared section by section, and the longest available version of each section is retained. Forms, routes, brands, labelers, product-listed strengths, and product-record counts are aggregated separately from ingredient-matched FDA NDC Directory records; package records listed above are associated with the linked SPL; and the normalized concept hierarchy comes from NLM RxNorm.
For canonical ingredient pages, bounded product-attributed indication and administration excerpts may be added to the AI evidence, and the generator is instructed to preserve available product, brand, route, and form qualifiers instead of treating one label as universal. Where a section is identified as AI-written, its plain-language text is generated from bounded label evidence. New draft drug pages remain in the admin review queue before first publication. Salix Pharmaceuticals, Inc. is the representative DailyMed label linked for verification and dates; it is not the sole source used for the page.
This is general education, not medical advice — always consult your doctor or pharmacist about your medications and any medical condition. For the exact wording of the linked representative label, view that label on DailyMed; some displayed composite sections may come from other in-scope SPL labels. Learn how we use AI and our data sources & update cadence.