Rifaximin (Xifaxan) for Traveler's Diarrhea: How It Works and How to Get It
An ER physician explains how rifaximin (Xifaxan) treats traveler's diarrhea, the 200 mg dosing, when it works, when it doesn't, and how to get a prescription.
Rifaximin (Xifaxan) for Traveler's Diarrhea: How It Works and How to Get It
Rifaximin (brand name Xifaxan) is a prescription antibiotic that is FDA-approved to treat traveler's diarrhea caused by noninvasive E. coli in people 12 and older. The standard dose is 200 mg taken three times a day for three days. What makes it different from most antibiotics is that it stays almost entirely in your gut: less than 0.4 percent is absorbed into your bloodstream, which is why it causes very few whole-body side effects. As an ER physician, here is the most important thing to understand: rifaximin works well for the common watery diarrhea travelers get, but it does NOT work when you have fever or bloody stool. Those signs point to invasive bacteria like Campylobacter, Shigella, or Salmonella, and the CDC recommends azithromycin instead. If your symptoms are watery, frequent, and miserable but you have no fever and no blood, rifaximin is an excellent, gentle option, and a clinician can call a prescription in to a pharmacy near you before you travel.
What Rifaximin Is and Why Travelers Use It
Rifaximin is a gut-selective antibiotic, which means it does its work inside the intestines and barely enters the rest of the body. The U.S. Food and Drug Administration first approved it for traveler's diarrhea in 2004, and it remains one of three antibiotic options the CDC lists for treating travelers, alongside azithromycin and the fluoroquinolones. Because so little of the drug is absorbed (under 0.4 percent reaches the bloodstream), rifaximin avoids many of the systemic side effects that come with broader antibiotics, and it has a low risk of interacting with other medications. For travelers who want a treatment they can carry in their kit and start the moment symptoms hit, that gentleness is the main appeal. It targets the most common bacterial cause of traveler's diarrhea, noninvasive Escherichia coli, which is responsible for a large share of cases in most regions.
How Rifaximin Works in the Gut
Rifaximin works by blocking bacterial RNA synthesis, which stops the offending bacteria in your intestines from multiplying. Because the drug concentrates in the gut rather than spreading through your body, it delivers a high local dose exactly where traveler's diarrhea lives. In the two randomized, double-blind, placebo-controlled trials the FDA reviewed, adults with traveler's diarrhea who took 200 mg three times daily recovered faster than those on placebo, with a shorter time to the last unformed stool. In plain terms, the medication shortens how long you are stuck near a bathroom. It does not instantly stop diarrhea the way an anti-motility drug like loperamide (Imodium) does; instead it treats the underlying bacterial infection so your gut can recover. Many clinicians, myself included, will pair an antibiotic with loperamide for faster symptom relief in adults, when appropriate.
Rifaximin Dosing for Traveler's Diarrhea
The approved adult and adolescent dose of rifaximin for traveler's diarrhea is 200 mg by mouth three times a day for three days, for a total of nine tablets. It can be taken with or without food. The 200 mg tablet is the strength used for traveler's diarrhea; the larger 550 mg tablet that pharmacies also stock is approved for different conditions (hepatic encephalopathy and IBS with diarrhea) and is not the traveler's diarrhea dose. If you do not feel meaningfully better after 24 to 48 hours, or if your diarrhea persists beyond 24 to 48 hours of treatment, worsens, or you develop fever or bloody stool, stop and seek medical care, because that pattern suggests a pathogen rifaximin cannot cover. Always finish only the course your clinician prescribes, and do not double up doses if you miss one.
When Rifaximin Is the Right Choice (and When It Is Not)
Rifaximin is best for mild to moderate, watery, nondysenteric traveler's diarrhea, the classic "I ate something and now I cannot leave the room" illness without fever or blood. The CDC's Yellow Book lists rifaximin as an option for severe, nondysenteric traveler's diarrhea, and it is a sensible self-treatment choice for many adults headed to regions where noninvasive E. coli dominates, such as much of Latin America. It is the wrong choice when warning signs are present. Per the FDA label, rifaximin should not be used if your diarrhea comes with fever or blood in the stool, or if it is caused by pathogens other than E. coli. Dysentery (bloody diarrhea, often with fever and cramping) usually means an invasive organism, and for those cases the CDC recommends azithromycin. Rifaximin also is not the answer for diarrhea that is clearly viral or for the watery, parasitic illnesses like giardia that need entirely different drugs.
Rifaximin vs Azithromycin vs Ciprofloxacin
Travelers often ask which antibiotic is "best." The honest answer is that it depends on your destination and your symptoms. Here is how the three main options compare for traveler's diarrhea.
The big-picture takeaway: azithromycin is the most versatile because it covers the invasive bacteria that cause fever and bloody stool, and it remains effective where fluoroquinolone resistance is high. Rifaximin shines for the common watery case and for travelers who want minimal whole-body side effects. Ciprofloxacin and other fluoroquinolones have fallen out of first-line favor because of rising resistance in Campylobacter and Shigella and a notable side-effect profile. For a deeper comparison of the two antibiotics travelers ask about most, see our guide on Cipro vs azithromycin for traveler's diarrhea.
Side Effects and Safety
Because rifaximin barely leaves the gut, its side effect profile is mild for most people. The most commonly reported effects in traveler's diarrhea trials were headache and, less often, nausea or an urge to have a bowel movement. Serious reactions are uncommon. Rifaximin is generally avoided in anyone with a known allergy to rifaximin or other rifamycin antibiotics (such as rifampin), and as with any antibiotic, Clostridioides difficile-associated diarrhea is a rare but recognized risk if symptoms worsen or change after treatment. Pregnant and breastfeeding travelers should not take rifaximin without a clinician's guidance, and dosing decisions for anyone with significant liver disease belong with a physician. None of this is a reason for healthy adult travelers to fear the drug; it is simply why a prescription requires a brief clinical review of your history and current medications.
How to Get Rifaximin Before Your Trip
Rifaximin is prescription-only in the United States, so you cannot buy it over the counter, but getting it before you leave is straightforward. The smartest approach is to handle it as part of your pre-trip planning rather than scrambling for a foreign clinic mid-trip.
Rifaximin and Prevention: What the Evidence Says
Some travelers ask whether they should take rifaximin every day to prevent diarrhea rather than treat it. Studies have looked at rifaximin for prevention (prophylaxis), and it can reduce the risk of traveler's diarrhea in certain situations, which is why you will see it discussed for high-risk travelers. That said, the CDC generally reserves routine antibiotic prophylaxis for select travelers, such as those with significant underlying illness, because widespread preventive use drives antibiotic resistance and exposes healthy people to medication they may not need. For most travelers, the better strategy is solid food and water precautions plus a treatment course of antibiotics on hand to use only if diarrhea actually develops. If you think you fall into a higher-risk category, that is a specific conversation to have with a clinician, not a do-it-yourself decision. Our complete traveler's diarrhea guide walks through prevention in more detail.
What to Pair With Rifaximin
Antibiotics treat the infection, but rehydration is what keeps traveler's diarrhea from becoming dangerous. The single most important thing you can do during any bout of diarrhea is replace lost fluids and electrolytes, ideally with oral rehydration salts dissolved in safe water. For adults with watery, nondysenteric diarrhea and no fever, loperamide (Imodium) can be added to an antibiotic to slow the gut and cut down on bathroom trips, and the combination often relieves symptoms faster than either alone. Skip loperamide if you have fever or bloody stool, since slowing the gut when an invasive infection is present can backfire. Bismuth subsalicylate (Pepto-Bismol) is another over-the-counter option for milder symptoms. Think of rifaximin as the tool that addresses the cause, while fluids and supportive medications manage how you feel while you recover.
Medical Disclaimer
This article is for general educational purposes and does not replace personalized medical advice. Rifaximin is a prescription medication, and whether it is right for you depends on your symptoms, history, and destination. If you have a high fever, blood in your stool, signs of significant dehydration, or diarrhea that lasts beyond a few days, seek medical care. Always consult a licensed clinician about your specific health conditions, medications, and travel plans before starting any treatment.
Frequently Asked Questions
Is rifaximin good for traveler's diarrhea? Yes, for the right type. Rifaximin is FDA-approved to treat traveler's diarrhea caused by noninvasive E. coli in people 12 and older, and clinical trials show it shortens how long symptoms last. It works best for watery diarrhea without fever or blood, and it is not effective against the invasive bacteria that cause bloody or feverish illness.
What is the rifaximin dose for traveler's diarrhea? The standard dose is 200 mg taken by mouth three times a day for three days, which is nine tablets total. It can be taken with or without food. The 200 mg tablet is the traveler's diarrhea strength; the 550 mg tablet is approved for other conditions and is not used for traveler's diarrhea.
How fast does rifaximin work? Many people feel meaningfully better within 24 to 48 hours of starting treatment. If your diarrhea has not improved after 24 to 48 hours, gets worse, or you develop fever or bloody stool, stop and seek medical care, because that pattern suggests a pathogen rifaximin does not cover.
Rifaximin or azithromycin for traveler's diarrhea? It depends on your symptoms and destination. Rifaximin is excellent for watery, nondysenteric diarrhea. Azithromycin is preferred when you have fever or bloody stool, and in regions with high antibiotic resistance such as South and Southeast Asia, because it covers invasive bacteria that rifaximin cannot.
Can I take rifaximin if I have a fever or bloody diarrhea? No. Per the FDA label, rifaximin should not be used for diarrhea complicated by fever or blood in the stool. Those signs point to invasive bacteria, and the CDC recommends azithromycin instead. Bloody or feverish diarrhea also warrants prompt medical evaluation.
Does rifaximin have a lot of side effects? Most people tolerate it well because less than 0.4 percent of the drug is absorbed into the bloodstream. The most common reported effects are headache and occasionally nausea. Serious reactions are uncommon. Avoid it if you are allergic to rifaximin or related rifamycin antibiotics, and talk to a clinician if you are pregnant or breastfeeding.
Do I need a prescription for rifaximin? Yes. Rifaximin is prescription-only in the United States.
Can rifaximin prevent traveler's diarrhea? Rifaximin has been studied for prevention and can reduce risk in some situations, but the CDC reserves routine antibiotic prophylaxis for select higher-risk travelers because of antibiotic resistance concerns. For most people, food and water precautions plus a treatment course on hand is the recommended strategy.
Sources
- U.S. Food and Drug Administration, "XIFAXAN (rifaximin) tablets: Full Prescribing Information." https://www.accessdata.fda.gov/drugsatfda_docs/label/2017/021361s023lbl.pdf
- CDC Yellow Book, 2026 edition, "Travelers' Diarrhea." https://www.cdc.gov/yellow-book/hcp/preparing-international-travelers/travelers-diarrhea.html
- CDC Yellow Book, 2026 edition, "Table 1.6.1, Acute diarrhea antibiotic treatment recommendations." https://www.ncbi.nlm.nih.gov/books/NBK620898/table/diarrhea.tab2/
- Riddle MS, et al. "Guidelines for the prevention and treatment of travelers' diarrhea: a graded expert panel report." Journal of Travel Medicine. https://pmc.ncbi.nlm.nih.gov/articles/PMC5731448/
- NIH LiverTox, "Rifaximin." https://www.ncbi.nlm.nih.gov/books/NBK548082/
- Merck Manual Professional Edition, "Traveler's Diarrhea." https://www.merckmanuals.com/professional/gastrointestinal-disorders/gastroenteritis/traveler-s-diarrhea
Alec Freling, MD is a board-certified emergency medicine physician and co-founder of Wandr Health with ER experience treating returning travelers.