Xifaxan (Rifaximin) - Oral

What Is Xifaxan?

Xifaxan (rifaximin) is an oral prescription antibiotic used to treat traveler’s diarrhea caused by certain bacteria and irritable bowel syndrome with diarrhea (IBS-D), a disorder of the large intestine. Healthcare providers also prescribe Xifaxan to prevent hepatic encephalopathy (HE), a condition that causes changes in thinking, behavior, and personality in adults with liver disease.

These changes occur when a toxin produced by certain bacteria in the gastrointestinal (GI) tract builds up and travels to the brain.

Xifaxan works by killing the bacteria that cause traveler’s diarrhea and IBS-D. For HE, Xifaxin kills the bacteria that produce the toxins responsible for symptoms.

This medication is available in tablet form.

Drug Facts

Generic Name: Rifaximin

Brand Name(s): Xifaxan

Administration Route(s): Oral

Drug Availability: Prescription

Therapeutic Classification: Antibiotic

Available Generically: No

Controlled Substance: N/A

Active Ingredient: Rifaximin

Dosage Form(s): Tablet

What Is Xifaxan Used For?

The Food and Drug Administration (FDA) approved Xifaxan to treat several conditions, including:

  • Traveler’s diarrhea: Xifaxan treats traveler’s diarrhea caused by certain bacteria (Escherichia coli, or E. coli) in adults and children aged 12 years and older. Xifaxan should not be used to treat diarrhea if you have blood in your stool or a fever. Traveler’s diarrhea describes symptoms that occur within 10 days of traveling to an area with poor public hygiene. Consuming water or food contaminated with bacteria (or other microbes) can cause this condition. Traveling to developing countries in Asia, Africa, Central America and South America, and the Middle East often poses the greatest risk.
  • Irritable bowel syndrome with diarrhea (IBS-D): Rifaxamin is prescribed for people with IBS-D, often when other treatments have failed. Several studies have shown a two-week trial of Xifaxan significantly improves diarrhea and bloating symptoms.
  • To prevent HE in adults with liver disease: People with liver disease have trouble removing naturally occurring toxins from their bodies. When these toxins build up, they can travel to the brain and cause symptoms, including confusion, slurred speech, and reduced alertness.
Xifaxan (Rifaximin) Drug Information - Illustration by Zoe Hansen

Verywell / Zoe Hansen

How to Take Xifaxan

Xifaxan is often taken two to three times per day, depending on what you are treating. Space your doses evenly throughout the day. You can take this medication with or without food.


Store Xifaxan at room temperature. Keep Xifaxan and all your medications in a safe location, up high and out of the reach of children and pets.

Off-Label Uses

Your healthcare provider may prescribe Xifaxan for other uses that are not approved by the FDA. This is called off-label use.

Some off-label uses of Xifaxan include:

How Long Does Xifaxan Take to Work?

How long Xifaxan takes to work will depend on the condition you are treating. For traveler’s diarrhea, most people begin to feel better by day two of treatment, but you should still finish your complete treatment. Two weeks of treatment is often needed for IBS-D treatment. Preventing hepatic encephalopathy requires long-term treatment.

What Are the Side Effects of Xifaxan?

This is not a complete list of side effects, and others may occur. A medical professional can advise you on side effects. If you experience other effects, contact your pharmacist or a medical professional. You may report side effects to the FDA at www.fda.gov/medwatch or 800-FDA-1088.

As with other medications, Xifaxan can cause side effects. Let your healthcare provider know if you experience any side effects while taking this medication.

Common Side Effects

Xifaxan is a well-tolerated medication. Most people don’t experience any side effects. 

However, the most common side effects include:

  • Dizziness 
  • Headache
  • Joint pain
  • Muscle spasms 
  • Nausea
  • Nose or throat irritation 
  • Stomach pain
  • Tiredness

Severe Side Effects

In rare cases, Xifaxan may cause severe side effects. Let your healthcare provider know right away if you develop any of the following reactions. Call 911 if your symptoms feel life-threatening.

Severe side effects of Xifaxan can include:

  • Swelling of the arms or legs (peripheral edema)
  • Swelling of the belly (ascites
  • Signs of an allergic reaction, including rash, hives, difficulty breathing, or swelling of the mouth, face, lips, tongue, or throat
  • Signs of C. diff infection, a severe and potentially life-threatening form of diarrhea: Let your healthcare provider know if you develop stomach pain, cramps, or very loose, watery, or bloody stools. Do not treat diarrhea with any over-the-counter (OTC) medications without talking with your provider first. OTC antidiarrheal products can cause severe complications if you have C. diff.

Long-Term Side Effects

Even though Xifaxan can be used to treat a C. diff infection, all antibiotics, including Xifaxan, can cause this condition. C. diff infection can occur while taking Xifaxan or months after stopping treatment. C. diff can sometimes cause severe, life-threatening bowel problems. Let your healthcare provider know right away if you develop stomach pain, cramps, or very loose, watery, or bloody stools. 

Do not treat diarrhea without talking with a medical professional first.

Report Side Effects

Xifaxan may cause other side effects. Call your healthcare provider if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your provider may send a report to the FDA's MedWatch Adverse Event Reporting Program or by phone (800-332-1088).

Dosage: How Much Xifaxan Should I Take?

Drug Content Provided and Reviewed by IBM Micromedex®

The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

  • For oral dosage form (tablets):
    • For treatment of irritable bowel syndrome with diarrhea:
      • Adults—550 milligrams (mg) three times a day for 14 days.
      • Children—Use and dose must be determined by your doctor.
    • For treatment of traveler's diarrhea:
      • Adults and children 12 years of age and older—200 milligrams (mg) three times a day for 3 days.
      • Children younger than 12 years of age—Use and dose must be determined by your doctor.
    • For preventing hepatic encephalopathy:
      • Adults—550 milligrams (mg) two times a day.
      • Children—Use and dose must be determined by your doctor.

Missed Dose

If you miss a dose of Xifaxan, take it as soon as you remember. If it’s almost time for your next dose, skip the missed dose and resume your normal dosing schedule. Do not double up or take extra.

Overdose: What Happens If I Take Too Much Xifaxan?

Only a minimal amount of Xifaxan is absorbed from your GI tract and into your bloodstream. For this reason, an overdose of Xifaxan is not expected to cause any serious problems.

What Happens If I Overdose on Xifaxan?

If you think you or someone else may have overdosed on Xifaxan, call a healthcare provider or the Poison Control Center (800-222-1222).

If someone collapses or isn't breathing after taking Xifaxan, call 911 immediately.


Drug Content Provided and Reviewed by IBM Micromedex®

It is very important that your doctor check the progress of you or your child to see if the medicine is working properly. This will allow your doctor to decide if you or your child should continue to take it.

Check with your doctor right away if the diarrhea does not stop in 1 or 2 days or if you or your child develop a fever or have blood in your stool.

A person can become dehydrated if too much fluid is lost from the body with diarrhea. Make sure you or your child drink plenty of fluids while you have diarrhea. Check with your doctor right away if you or your child have more than one of the following symptoms: decreased urination, dizziness, dry mouth, increased thirst, or lightheadedness.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.

What Are Reasons I Shouldn’t Take Xifaxan?

You should not take Xifaxan if you’ve had an allergic reaction to Xifaxan in the past or are allergic to other rifamycin antibiotics, including Rifadin or Rimactane (rifampin), Priftin (rifapentine), or Mycobutin (rifabutin).

What Other Medications Interact With Xifaxan?

Certain medications may interact with Xifaxan. Be sure to let your healthcare provider know all the medicines you take, including over-the-counter vitamins, supplements, and herbal products.

Medications that may interact with Xifaxan include:

This is not a complete list of all the drugs that may interact with Xifaxan. Be sure to ask your doctor or pharmacist before starting anything new.

Frequently Asked Questions

  • What is Xifaxan used for?

    Xifaxan is used to treat traveler’s diarrhea and irritable bowel syndrome with diarrhea (IBS-D). Xifaxan is also used to prevent hepatic encephalopathy, which can cause confusion, slurred speech, and reduced alertness in people with liver disease. Your healthcare provider may prescribe Xifaxan to treat other conditions as well. 

  • How does Xifaxan work?

    Xifaxan is an antibiotic medication. It works by killing the bacteria that cause certain forms of traveler’s diarrhea and IBS-D. Xifaxan also kills toxin-producing bacteria that contribute to hepatic encephalopathy symptoms.

  • What are the side effects of Xifaxan?

    Xifaxan is a well-tolerated medication, but side effects can sometimes occur. Common side effects include dizziness, headache, joint pain, muscle spasms, nausea, nose or throat irritation, stomach pain, and tiredness.

How Can I Stay Healthy While Taking Xifaxan?

Xifaxan primarily works in the gut, and very little is absorbed into other areas of the body. This makes Xifaxan a well-tolerated medication, and most people have no trouble taking it. However, all medicines carry some risk.

Dietary changes can also help with diarrhea symptoms and ease other symptoms associated with IBS-D. These include:

  • Eating smaller meals
  • Staying away from high-fat meals and fried meals
  • Identifying and avoiding your IBS trigger foods

There are other lifestyle adjustments you can make to stay healthy, such as:

  • Limiting alcohol consumption
  • Reducing exposure to toxins
  • Exercising and maintaining a healthy weight
  • Seeing your healthcare provider regularly

Let your healthcare provider know if you experience any signs of a serious reaction, including swelling of the legs, arms, or belly. Reporting any adverse reactions as soon as they occur will help keep you healthy and safe while taking Xifaxan or any other medication.

Medical Disclaimer

Verywell Health's drug information is meant for educational purposes only and is not intended as a replacement for medical advice, diagnosis, or treatment from a healthcare professional. Consult your doctor before taking any new medication(s). IBM Watson Micromedex provides some of the drug content, as indicated on the page.

8 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  2. Food and Drug Administration. Xifaxan label.

  3. John Hopkins Medicine. Traveler’s diarrhea.

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  5. Cleveland Clinic. Hepatic encephalopathy.

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