rifaximin
Brand names: Xifaxan
Xifaxan is an antibiotic medicine. It helps treat traveler's diarrhea and irritable bowel syndrome with diarrhea (IBS-D). It also lowers the risk of hepatic encephalopathy (HE) coming back.
Drug Pricing (NADAC)
Brand Price
$52.22/unit
Generic Available
No
SALIX PHARMS
Pricing data from NADAC (CMS), effective December 18, 2024. Compare all drug costs →
What it does
Xifaxan can treat traveler's diarrhea caused by certain germs in adults and kids 12 and older.
Common side effects
Headache, Swelling in your legs or ankles, Nausea
Key warnings
Xifaxan may not work if you have a fever or blood in your stool.
How It Works
Xifaxan is an antibiotic that works in your gut. It stops the growth of certain bacteria that can cause diarrhea or other problems. It also reduces the amount of ammonia in your body, which can help with HE.
How to Take It
For traveler's diarrhea, take 200 mg three times a day for 3 days. For HE, take 550 mg two times a day. For IBS-D, take 550 mg three times a day for 14 days. You can take Xifaxan with or without food.
Pregnancy & Breastfeeding
Xifaxan may harm your unborn baby. Tell your doctor if you are pregnant or plan to become pregnant. It is not known if Xifaxan passes into breast milk, so talk to your doctor about the best way to feed your baby if you take Xifaxan.
Missed Dose
If you miss a dose, take it as soon as you remember. If it is close to your next dose, skip the missed dose and continue with your regular schedule.
Storage
Store Xifaxan tablets at room temperature (68° to 77°F).
Side Effects (from patient reports)
Based on 12,888 FDA adverse event reports.
FDA Adverse Event Report Analysis
Detailed analysis of 19,891 reports from the FDA Adverse Event Reporting System (FAERS). Reports span 2004–2025.
Total Reports
19,891
Death-Related Reports
5,855
Hospitalization Reports
7,784
Top Indication
Product Used For Unknown Indication
Gender Distribution
Age Distribution
Most Reported Adverse Reactions (FAERS)
| # | Reaction | Reports |
|---|---|---|
| 1 | DEATH | 3,982 |
| 2 | HOSPITALISATION | 1,704 |
| 3 | DIARRHOEA | 1,193 |
| 4 | OFF LABEL USE | 1,133 |
| 5 | THERAPY INTERRUPTED | 989 |
| 6 | AMMONIA INCREASED | 831 |
| 7 | NAUSEA | 802 |
| 8 | FATIGUE | 779 |
| 9 | HEPATIC ENCEPHALOPATHY | 762 |
| 10 | DRUG INEFFECTIVE | 713 |
| 11 | CONFUSIONAL STATE | 711 |
| 12 | INABILITY TO AFFORD MEDICATION | 679 |
| 13 | HEPATIC CIRRHOSIS | 657 |
| 14 | INSURANCE ISSUE | 623 |
| 15 | FALL | 607 |
Reactions in Death Reports
Reactions in Hospitalization Reports
Source: FDA FAERS (Adverse Event Reporting System) FDA FAERS (Adverse Event Reporting System) Reports are voluntary and do not establish causation
Serious Warnings
Xifaxan may not work if you have a fever or blood in your stool. It may also not work for diarrhea caused by germs other than E. coli. If your diarrhea gets worse or lasts more than 1-2 days, stop taking Xifaxan and talk to your doctor. Diarrhea caused by C. difficile can happen with almost all antibiotics, including Xifaxan. Use Xifaxan with caution if you have severe liver problems.
Known Drug Interactions
( 7.2 ) 7.1 P-glycoprotein Inhibitors Concomitant administration of cyclosporine, an inhibitor of P-gp and OATPs significantly increased the systemic exposure of rifaximin. Caution should be exercised when concomitant use of XIFAXAN and a P-gp inhibitor such as cyclosporine is needed [see Warnings and Precautions ( 5.5 ), Clinical Pharmacology ( 12.3 )].
Mechanism: Cyclosporine stops certain proteins from removing rifaximin from the body, which causes rifaximin levels to rise.
What to do: Use this combination with caution and report any new symptoms to your healthcare provider.
7 DRUG INTERACTIONS Warfarin: Monitor INR and prothrombin time; dose adjustment of warfarin may be needed to maintain target INR range. 7.2 Warfarin Changes in INR have been reported postmarketing in patients receiving rifaximin and warfarin concomitantly. Dose adjustment of warfarin may be needed to maintain target INR range.
Mechanism: Rifaximin can affect how your body processes blood thinners, which may change your risk of bleeding or how quickly your blood clots.
What to do: Your doctor should check your blood clotting tests often and may need to adjust your warfarin dose to keep it in the safe range.
Common Questions
Can I take Xifaxan if I'm allergic to rifampin?
What should I tell my doctor before taking Xifaxan?
Can Xifaxan cause other problems?
How long should I take Xifaxan?
Can I drink alcohol while taking Xifaxan?
What if my IBS-D symptoms come back after treatment?
Does Xifaxan interact with other medications?
Can children take Xifaxan?
What are the symptoms of hepatic encephalopathy?
What if I accidentally take too much Xifaxan?
What are the common side effects of rifaximin?
Does rifaximin interact with other medications?
What drug class is rifaximin?
Is rifaximin safe during pregnancy?
Related Medications in Non-Systemic Antibiotic (IBS-D)
Other drugs grouped near rifaximin — same-class peers and common alternatives.
alosetron
Lotronex
Alosetron (Lotronex) is a medicine for women with severe diarrhea-predominant irritable bowel syndrome (IBS).
Compare with rifaximin →
aprepitant
Emend
Aprepitant (Emend) is a medicine that helps prevent nausea and vomiting.
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bisacodyl
Dulcolax
Bisacodyl is a medicine that helps you have a bowel movement.
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bismuth subsalicylate
Pepto-Bismol
Bismuth subsalicylate (Pepto-Bismol) is a medicine that can treat diarrhea and upset stomach.
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cimetidine
Tagamet
Cimetidine (Tagamet) reduces stomach acid.
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Medication Guides
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Common Drug Interactions
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Related Health & Safety Data
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Search prescribers for Non-Systemic Antibiotic (IBS-D)
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💉 Procedure Costs
Medicare procedure pricing for 9,297 procedures
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What the FDA Data Shows for rifaximin
The FDA label for rifaximin (sold under brand names such as Xifaxan) classifies it as a prescription-only medication in the Non-Systemic Antibiotic (IBS-D) class. Xifaxan can treat traveler's diarrhea caused by certain germs in adults and kids 12 and older. Official labeling lists 12 commonly reported side effects, including Headache, Swelling in your legs or ankles, Nausea.
Post-market surveillance from the FDA Adverse Event Reporting System (FAERS) captures real-world experience. For this drug, FAERS contains 12,888 voluntary reports. The database also lists 2 documented drug interactions derived from FDA labeling, with the top-flagged interaction rated moderate severity. NADAC pricing from CMS.
Report counts do not establish causation — a FAERS entry documents a temporal association, not proof that the drug produced the outcome. Widely prescribed medications naturally accumulate more reports than niche therapies, so raw totals must be interpreted alongside total exposure. Shortage status, recall history, and patent information further shape supply and switching decisions. This page summarizes public FDA data for educational purposes only and is not a substitute for professional medical advice — always consult a licensed healthcare provider before starting, stopping, or changing any medication.
Data Sources
Drug labeling: FDA Drug Labels (SPL/DailyMed). Adverse events: FDA Adverse Event Reporting System (FAERS). Pricing: CMS National Average Drug Acquisition Cost (NADAC).
FAERS reports are voluntary and do not establish causation. Drug interactions are derived from FDA labeling and clinical references. Always consult a healthcare professional before making medication decisions.
Last updated: August 27, 2025
Read our methodology — how this data is sourced, computed, and verified.
All federal data sources used on this page
- FDA Orange Book — approved drug products with therapeutic equivalence. accessdata.fda.gov/cder/ob
- FDA DailyMed — NIH-hosted drug labeling for FDA-approved meds. dailymed.nlm.nih.gov
- FDA Adverse Event Reporting System (FAERS) — post-marketing safety surveillance. fda.gov/drugs/faers
- NLM RxNorm — standardized clinical drug nomenclature. nlm.nih.gov/research/umls/rxnorm
- CMS Medicare Part B Drug Average Sales Price Files — federal drug pricing data. cms.gov/medicare/part-b-drugs/asp
- FDA Drug Shortages Database — current and resolved drug shortage tracking. accessdata.fda.gov/drugshortages