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xifaxan

Xifaxan (Rifaximin) is a rifamycin antibacterial used to treat Diarrhea, Irritable Bowel Syndrome.

Rifaximin · by Salix

Not yet rated· sourced from the FDA label
Rated against independent regulatory sources·Last updated June 7, 2026·How we rate
Verified againstopenFDANIH DailyMedRxClass

Key facts

Active ingredient
Rifaximin
Form
Tablet
Strength
Rifaximin 200MG · Rifaximin 550MG
Type
Prescription (Rx)
Brand or generic
Brand-name
Manufacturer
Salix
FDA application
NDA021361

What is Xifaxan?

From the FDA label:XIFAXAN tablets contain rifaximin, a non-aminoglycoside semi-synthetic, nonsystemic antibiotic derived from rifamycin SV. Rifaximin is a structural analog of rifampin. The chemical name for rifaximin is (2 S ,16 Z ,18 E ,20 S ,21 S ,22 R ,23 R ,24 R ,25 S ,26 S ,27 S ,28 E )-5,6,21,23,25-pentahydroxy-27-methoxy-2,4,11,16,20,22,24,26-octamethyl-2,7-(epoxypentadeca-[1,11,13]trienimino)benzofuro[4,5-e]pyrido[1,2-á]-benzimidazole-1,15(2 H )-dione,25- acetate. The empirical formula is C43H51N3O11 and its molecular weight is 785.9. The chemical structure is represented below: XIFAXAN tablets for oral administration are film-coated and contain 200 mg or 550 mg of rifaximin. Inactive ingredients: Each 200 mg tablet contains colloidal silicon dioxide, disodium edetate, glycerol palmitostearate, hypromellose, microcrystalline cellulose, propylene glycol, red iron oxide, sodium starch glycolate, talc, and titanium dioxide. Each 550 mg tablet contains colloidal silicon dioxide, glycerol palmitostearate, microcrystalline cellulose, polyethylene glycol/macrogol, polyvinyl alcohol, red iron oxide, sodium starch glycolate, talc, and titanium dioxide. chem structure

How to use

Condition Recommended Oral Dosage TD ( 2.1 ) 200 mg 3 times a day for 3 days HE ( 2.2 ) 550 mg 2 times a day IBS-D ( 2.3 ) 550 mg 3 times a day for 14 days. Patients who experience recurrence can be retreated up to 2 times with the same regimen. XIFAXAN can be taken with or without food. ( 2.4 ) 2.1 Dosage for Travelers’ Diarrhea The recommended dosage of XIFAXAN is 200 mg taken orally three times a day for 3 days. 2.2 Dosage for Hepatic Encephalopathy The recommended dosage of XIFAXAN is 550 mg taken orally two times a day. 2.3 Dosage for Irritable Bowel Syndrome with Diarrhea The recommended dosage of XIFAXAN is 550 mg taken orally three times a day for 14 days. Patients who experience a recurrence of symptoms can be retreated up to two times with the same dosage regimen. 2.4 Administration XIFAXAN can be taken with or without food [see Clinical Pharmacology ( 12.3 )].

Side effects

The following clinically significant adverse reactions are described elsewhere in labeling: • Clostridium difficile -associated diarrhea [see Warnings and Precautions ( 5.2 )] Most common adverse reactions: • TD (≥2%): Headache ( 6.1 ) • HE (≥10%): Peripheral edema, nausea, constipation, dizziness, fatigue, urinary tract infection, insomnia, anemia, pruritus, and ascites ( 6.1 ) • IBS-D (≥2%): ALT increased, nausea ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Salix Pharmaceuticals at 1-800-321-4576 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. Travelers’ Diarrhea The safety of XIFAXAN 200 mg taken three times a day was evaluated in patients with travelers’ diarrhea consisting of 320 patients in two placebo-controlled clinical trials with 95% of patients receiving three or four days of treatment with XIFAXAN. The population studied had a mean age of 31.3 (18-79) years of which approximately 3% were ≥65 years old, 53% were male and 84% were White, 11% were Hispanic. Discontinuations due to adverse reactions occurred in 0.4% of patients. The adverse reactions leading to…

Warnings

Important safety information

Travelers’ Diarrhea Not Caused by E. coli : XIFAXAN was not effective in diarrhea complicated by fever and/or blood in the stool or diarrhea due to pathogens other than E. coli . If diarrhea symptoms get worse or persist for more than 24 to 48 hours, discontinue XIFAXAN and consider alternative antibiotics. ( 5.1 ) • Clostridium difficile -Associated Diarrhea: Evaluate if diarrhea occurs after therapy or does not improve or worsens during therapy. ( 5.2 ) • Hepatic Impairment: Use with caution in patients with severe (Child-Pugh Class C) hepatic impairment. ( 5.4 , 8.7 ) • Concomitant P-glycoprotein (P-gp) inhibitors (e.g., cyclosporine): Caution should be exercised when concomitant use of XIFAXAN and a P-glycoprotein inhibitor is needed. ( 5.5, 7.1 ) 5.1 Travelers’ Diarrhea Not Caused by Escherichia coli XIFAXAN was not found to be effective in patients with diarrhea complicated by fever and/or blood in the stool or diarrhea due to pathogens other than Escherichia coli. Discontinue XIFAXAN if diarrhea symptoms get worse or persist more than 24 to 48 hours and alternative antibiotic therapy should be considered. XIFAXAN is not effective in cases of travelers’ diarrhea due to Campylobacter jejuni . The effectiveness of XIFAXAN in travelers’ diarrhea caused by Shigella spp. and Salmonella spp. has not been proven. XIFAXAN should not be used in patients where Campylobacter jejuni, Shigella spp., or Salmonella spp. may be suspected as causative pathogens [ see Indications and Usage ( 1.1 )]. 5.2 Clostridium difficile- Associated Diarrhea Clostridium difficile- associated diarrhea (CDAD) has been reported with use of nearly all antibacterial agents, including XIFAXAN, and may range in severity from mild diarrhea to fatal colitis. Treatment with antibacterial agents alters the normal flora of the colon which may lead to overgrowth of C. difficile. C. difficile produces toxins A and B which contribute to the development of CDAD. Hypertoxin producing strains of C. difficile cause increased morbidity and mortality, as these infections can be refractory to antimicrobial therapy and may require colectomy. CDAD must be considered in all patients who present with diarrhea following antibiotic use. Careful medical history is necessary since CDAD has been reported to occur over two months after the administration of antibacterial agents. If CDAD is suspected or confirmed, ongoing antibiotic use not directed against C. difficile may need to be discontinued. Appropriate fluid and electrolyte management, protein supplementation, antibiotic treatment of C . difficile, and surgical evaluation should be instituted as clinically indicated. 5.3 Development of Drug-Resistant Bacteria Prescribing XIFAXAN for travelers’ diarrhea in the absence of a proven or strongly suspected bacterial infection or a prophylactic indication is unlikely to provide benefit to the patient and increases the risk of the development of drug-resistant bacteria. 5.4 Severe (Child-Pugh Class C) Hepatic Impairment There is increased systemic exposure in patients with severe hepatic impairment. The clinical trials were limited to patients with MELD scores <25. Therefore, caution should be exercised when administering XIFAXAN to patients with severe hepatic impairment (Child-Pugh Class C) [ see Use in Specific Populations ( 8.7 ), Clinical Studies ( 14.2 )]. 5.5 Concomitant Use with P-glycoprotein Inhibitors Concomitant administration of drugs that are P-glycoprotein (P-gp) inhibitors with XIFAXAN can substantially increase the systemic exposure to rifaximin. Caution should be exercised when concomitant use of XIFAXAN and a P-gp inhibitor such as cyclosporine is needed. In patients with hepatic impairment, a potential additive effect of reduced metabolism and concomitant P-gp inhibitors may further increase the systemic exposure to rifaximin [see Drug Interactions ( 7.1 ), Clinical Pharmacology ( 12.3 )].

Who should not take Xifaxan

XIFAXAN is contraindicated in patients with a hypersensitivity to rifaximin, any of the rifamycin antimicrobial agents, or any of the components in XIFAXAN. Hypersensitivity reactions have included exfoliative dermatitis, angioneurotic edema, and anaphylaxis [see Adverse Reactions ( 6.2 )] . History of hypersensitivity to rifaximin, rifamycin antimicrobial agents, or any of the components of XIFAXAN. ( 4) )

Overdose — what happens if you take too much

No specific information is available on the treatment of overdosage with XIFAXAN. In clinical studies at doses higher than the recommended dose (greater than 600 mg per day for TD, greater than 1,100 mg per day for HE or greater than 1,650 mg per day for IBS-D), adverse reactions were similar in subjects who received doses higher than the recommended dose and placebo. In the case of overdosage, discontinue XIFAXAN, treat symptomatically, and institute supportive measures as required.

U.S. Poison Control: call or text 1-800-222-1222 (free, 24/7). In an emergency call 911. From the FDA label; not medical advice.

Interactions

Warfarin: Monitor INR and prothrombin time; dose adjustment of warfarin may be needed to maintain target INR range. ( 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. In patients with hepatic impairment, a potential additive effect of reduced metabolism and concomitant P-gp inhibitors may further increase the systemic exposure to 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 )]. 7.2 Warfarin Changes in INR have been reported postmarketing in patients receiving rifaximin and warfarin concomitantly. Monitor INR and prothrombin time. Dose adjustment of warfarin may be needed to maintain target INR range. See prescribing information for warfarin. 7.3 CYP3A4 Substrates An in vitro study has suggested that rifaximin induces CYP3A4 [see Clinical Pharmacology ( 12.3 )] . However, in patients with normal liver function, XIFAXAN at the recommended dosing regimen is not expected to induce CYP3A4. It is unknown whether rifaximin can have a significant effect on the pharmacokinetics of concomitant CYP3A4 substrates in patients with reduced liver function who have elevated rifaximin concentrations.

Storing Xifaxan, and how long it keeps

Quoted from this product’s own FDA label. Storage belongs to the product and its device, not to the drug in general — a pen and a tablet of the same medicine are kept completely differently.

  • Store XIFAXAN Tablets at 20° to 25°C (68° to 77°F); excursions permitted to 15° to 30°C (59° to 86°F) [see USP Controlled Room Temperature].

Drug class

May treat (source: NIH RxClass)

Dosage forms

Tablet

The forms currently marketed in the U.S., per the FDA National Drug Code Directory.

Ways to save

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Frequently asked questions

What does Xifaxan treat?
Xifaxan (Rifaximin) may be used to treat diarrhea, irritable bowel syndrome, based on NIH RxClass drug-classification data (conditions a drug may treat — not a verbatim copy of the FDA-approved label). This is general reference, not medical advice.
Is there a coupon or discount for Xifaxan?
pharmaranks is an independent ratings site, not a pharmacy — we don't issue coupons or sell Xifaxan. To pay less, ask your prescriber or pharmacist whether a generic equivalent exists, check the manufacturer's copay/savings card and patient-assistance program, and compare a pharmacy discount card against your insurance copay. Prices vary by pharmacy, insurance, and location, so always confirm at the counter. This is general reference, not medical or financial advice.
Who makes Xifaxan?
Xifaxan is marketed by Salix. You can see Salix's full profile, rating, and other products on pharmaranks.
Is Xifaxan a brand-name or generic drug?
Xifaxan is a brand-name product with the active ingredient Rifaximin.
Is Xifaxan available over the counter?
No. Xifaxan is a prescription (Rx) medication in the US — you need a prescription from a licensed clinician (in person or via telehealth); it isn't sold over the counter. For some conditions there are OTC alternatives — ask your pharmacist.
What forms does Xifaxan come in?
Xifaxan is currently marketed as tablet, per the FDA's National Drug Code Directory.
What class of drug is Xifaxan?
Xifaxan is classified as rifamycin antibacterial, per the FDA's Established Pharmacologic Class.
Is Xifaxan FDA-registered?
Xifaxan is on record with the U.S. FDA under application number NDA021361. You can verify this on its official FDA label.
Is Xifaxan safe?
There's no single safe-or-not verdict, and we don't yet have a composite recall-safety score for Xifaxan. Review its FDA-label side effects and warnings below, and always consult a licensed professional.
What are the side effects of Xifaxan?
Xifaxan's side effects are taken directly from its FDA label. From the label: The following clinically significant adverse reactions are described elsewhere in labeling: • Clostridium difficile -associated diarrhea [see Warnings and Precautions ( 5.2 )] Most common adverse reactions: • TD (≥2%): Headache ( 6.1 ) • HE (≥10%): Peripheral edema, nausea, constipation, dizziness,… Both common and serious reactions are documented in full on this page. This is general reference from the FDA, not medical advice — always consult a professional.

Clinical content sourced from the FDA label via openFDA (U.S. FDA). View the FDA label on DailyMed → Provided for general reference only — not medical advice. Always consult a licensed professional and the current prescribing information.

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