Comprehensive medication guide to Rifaximin including estimated pricing, availability information, side effects, and how to find it in stock at your local pharmacy.
Estimated Insurance Pricing
$30–$150 copay; Tier 3 or specialty tier on most formularies, prior authorization and step therapy often required.
Estimated Cash Pricing
$1,800–$2,400 retail for a 30-day supply (60 tablets of 550 mg); manufacturer savings card may reduce cost to $0–$75 for eligible commercially insured patients.
Medfinder Findability Score
55/100
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Rifaximin is a non-absorbable rifamycin antibiotic that works locally in the gastrointestinal tract. It is sold under the brand name Xifaxan and is manufactured by Salix Pharmaceuticals (a Bausch Health company). Rifaximin is FDA-approved for three indications: treating travelers' diarrhea caused by noninvasive strains of E. coli in patients 12 and older, reducing the risk of overt hepatic encephalopathy recurrence in adults with liver disease, and treating irritable bowel syndrome with diarrhea (IBS-D) in adults. It is also widely prescribed off-label for small intestinal bacterial overgrowth (SIBO), Clostridioides difficile infection, and certain inflammatory bowel conditions.
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Rifaximin works by inhibiting bacterial RNA synthesis. It binds to the beta-subunit of bacterial RNA polymerase, effectively blocking the bacteria's ability to transcribe genetic information and reproduce. What makes Rifaximin unique is that less than 0.4% of the drug is absorbed systemically — it stays almost entirely in the gut. This means it targets harmful gut bacteria directly while minimizing systemic side effects. For hepatic encephalopathy, it reduces ammonia-producing bacteria in the intestines. For IBS-D and SIBO, it helps rebalance the gut microbiome.
200 mg oral tablet — tablet
Used for travelers' diarrhea caused by noninvasive E. coli (200 mg three times daily for 3 days)
550 mg oral tablet — tablet
Used for reducing the risk of hepatic encephalopathy recurrence (550 mg twice daily, ongoing) and for IBS-D (550 mg three times daily for 14 days)
Rifaximin (brand name Xifaxan) scores a 55 out of 100 on our findability scale, meaning it can be intermittently difficult to locate. Because no generic is available in the United States — and won't be until at least 2029 — Rifaximin is manufactured by a single source (Salix Pharmaceuticals/Bausch Health). Increased prescribing for IBS-D and off-label SIBO treatment has driven higher demand, leading to periodic supply disruptions at retail pharmacies. While Rifaximin is not currently listed on the FDA drug shortage database, many patients report having to call multiple pharmacies to find it in stock. Using Medfinder can save you time by locating pharmacies that have Rifaximin available near you.
Rifaximin is most commonly prescribed by gastroenterologists and hepatologists, particularly for hepatic encephalopathy and IBS-D. However, it can also be prescribed by:
Telehealth consultations are available for Rifaximin prescriptions in many cases, which can be especially helpful if you're having difficulty finding a specialist.
No, Rifaximin is not a controlled substance. It is not scheduled by the DEA and does not have abuse potential. You do need a valid prescription from a licensed healthcare provider to obtain it, but there are no special prescribing restrictions like those required for controlled substances.
Because Rifaximin is minimally absorbed, it generally has a favorable side effect profile. Common side effects include:
Serious but rare side effects to watch for include Clostridioides difficile-associated diarrhea, drug-resistant bacterial superinfection, and severe allergic reactions (hives, rash, swelling, or difficulty breathing). Contact your healthcare provider immediately if you experience any of these. Rifaximin does not carry an FDA boxed warning.
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Lactulose
An osmotic laxative and the standard first-line treatment for hepatic encephalopathy; much less expensive than Rifaximin
Neomycin
An aminoglycoside antibiotic sometimes used for hepatic encephalopathy, though with more side effects
Metronidazole (Flagyl)
Used for SIBO, C. difficile infections, and various GI infections; available as an affordable generic
Alosetron (Lotronex)
A 5-HT3 antagonist approved for severe IBS-D in women who haven't responded to other treatments
Prefer Rifaximin? We can find it.
Warfarin
moderateRifaximin may decrease warfarin's effectiveness in patients with hepatic impairment; monitor INR closely
CYP3A4 substrates
moderatePotential interaction in patients with hepatic impairment where systemic absorption of Rifaximin is increased
P-glycoprotein inhibitors (e.g., Cyclosporine)
moderateMay significantly increase Rifaximin systemic exposure
Live vaccines (e.g., typhoid vaccine)
moderateRifaximin may reduce vaccine effectiveness
Rifaximin is a highly effective gut-targeted antibiotic with a strong safety profile, but its brand-only status and high cost make it challenging for many patients. With no generic available in the US until at least 2029 and a cash price of $1,800–$2,400 per month, insurance coverage and manufacturer savings programs are essential for affordability. Supply can be intermittent due to single-source manufacturing and growing demand. If you're struggling to find Rifaximin in stock, Medfinder can help you locate pharmacies near you that have it available. Be sure to explore the Xifaxan Savings Card and patient assistance programs through Bausch Health if cost is a barrier.
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