Xifaxan (rifaximin) is a prescription drug that’s used to treat diarrhea from certain causes and to prevent episodes of hepatic encephalopathy. It comes as a tablet. It’s usually taken two or three times per day.

Doctors prescribe Xifaxan:

The active ingredient in Xifaxan is rifaximin. (An active ingredient is what makes a drug work.) Xifaxan comes as a tablet that you swallow. Xifaxan is an antibiotic.

This article describes the dosages of Xifaxan, as well as its strengths and how to take it. To learn more about Xifaxan, see this in-depth article.

* Xifaxan is only prescribed for traveler’s diarrhea caused by certain kinds of E. coli. This bacterium causes watery diarrhea. If you have bloody diarrhea or a fever, your doctor will not prescribe Xifaxan.

The table below highlights the basics of Xifaxan’s dosage. All doses are listed in milligrams (mg).

ConditionDosage and length of treatment
traveler’s diarrhea caused by Escherichia coli (E. coli) bacterium*200 mg three times per day for 3 days
irritable bowel syndrome with diarrhea (IBS-D)550 mg three times per day for 14 days
hepatic encephalopathy550 mg twice per day, prescribed long term

* Xifaxan is only prescribed for traveler’s diarrhea caused by certain kinds of E. coli. This bacterium causes watery diarrhea. If you have bloody diarrhea or a fever, your doctor will recommend a different treatment.

What is Xifaxan’s form?

Xifaxan comes as a tablet that you swallow.

What strengths does Xifaxan come in?

Xifaxan tablets come in two strengths: 200 mg and 550 mg.

What are the usual dosages of Xifaxan?

The information below describes dosages that are commonly used or recommended. But be sure to take the dosage your doctor prescribes for you. They’ll determine the best dosage to fit your needs.

Dosage for traveler’s diarrhea

If you develop traveler’s diarrhea, your doctor may prescribe Xifaxan. The dosage is 200 mg three times per day for 3 days.

Xifaxan is used when the cause of the diarrhea is believed to be a bacterial infection with noninvasive E. coli. This bacterium causes watery diarrhea. If you have bloody diarrhea or a fever, your doctor will recommend a different treatment.

Dosage for irritable bowel syndrome (IBS)

If you have IBS with diarrhea (IBS-D), your doctor may prescribe 550 mg of Xifaxan for you to take three times per day for 14 days. If your symptoms return, your doctor may repeat this 14-day treatment up to two times.

Dosage for hepatic encephalopathy

If you’ve experienced hepatic encephalopathy from liver disease, your doctor may prescribe Xifaxan to reduce your risk of having more episodes. The recommended dosage is 550 mg of Xifaxan twice per day.

What’s the dosage of Xifaxan for children?

Doctors may prescribe Xifaxan for children ages 12 years and older with traveler’s diarrhea caused by a certain kind of E. coli bacterium. The recommended dosage and length of treatment for children is the same as for adults: 200 mg three times per day for 3 days.

Is Xifaxan used long term?

Whether Xifaxan is used long term depends on the condition it’s prescribed for.

Xifaxan is usually prescribed as a long-term treatment to decrease the risk of having repeated episodes of hepatic encephalopathy. If you and your doctor determine that Xifaxan is safe and effective for your condition, you’ll likely take it long term.

But Xifaxan is used short term for traveler’s diarrhea and IBS-D. Doctors prescribe Xifaxan for 3 days to treat traveler’s diarrhea and for 14 days at a time to treat IBS-D.

Below are answers to some commonly asked questions about Xifaxan’s dosage.

Should I take my dose of Xifaxan before or after food, or are there any foods to avoid?

You can take Xifaxan before or after food. Food doesn’t affect the amount of Xifaxan your body absorbs. And you don’t need to avoid any specific foods while taking Xifaxan.

If you have diarrhea, it’s important to continue to drink fluids to prevent dehydration. Your doctor may suggest you continue to eat nutritious foods. If you have questions or concerns about how to stay hydrated and nourished, talk with your doctor or pharmacist.

Can Xifaxan be used for small intestinal bacterial overgrowth (SIBO)? If so, what is the dosage?

Xifaxan is not approved as a treatment for SIBO. But your doctor may prescribe Xifaxan off-label for this use. With off-label use, doctors prescribe a drug for a purpose other than what it’s approved for.

In studies, SIBO resolved in 70.8% of people who took rifaximin (the active ingredient in Xifaxan).

The drug’s manufacturer doesn’t provide dosage recommendations for unapproved uses. If you’d like to learn more about taking Xifaxan for SIBO, talk with your doctor.

The dosage of Xifaxan you’re prescribed depends on the type and severity of the condition you’re using the drug to treat.

Your doctor will also monitor you more closely if you have severe liver disease or are taking a type of medication called a P-glycoprotein blocker, such as quinidine or cyclosporine.

Xifaxan comes as a tablet that you swallow. It may be taken with or without food.

If you have trouble swallowing tablets, see this article for tips on how to take this form of medication.

For information on the expiration, storage, and disposal of Xifaxan, see this article.

Accessible drug containers and labels

Some pharmacies provide medication labels that:

  • have large print
  • use braille
  • feature a code you can scan with a smartphone to change the text to audio

Your doctor or pharmacist may be able to recommend pharmacies that offer these accessibility features if your current pharmacy doesn’t.

Let your pharmacist know if you have trouble opening medication bottles. They may have tips to help, or they may be able to supply Xifaxan in an easy-open container.

If you miss a dose of Xifaxan, take it as soon as you remember. But if you’re close to taking your next scheduled dose, skip the missed dose entirely. Take your next dose at your regularly scheduled time. Do not take two doses of Xifaxan at once to make up for a missed dose.

If you’re unsure when to take Xifaxan after missing a dose, talk to your doctor or pharmacist. Missing doses of Xifaxan can affect how well the drug works.

If you need help remembering to take your dose of Xifaxan on time, try using a medication reminder. This can include setting an alarm or downloading a reminder app on your phone.

Do not take more Xifaxan than your doctor prescribes, as this can lead to harmful effects.

What to do in case you take too much Xifaxan

Call your doctor right away if you think you’ve taken too much Xifaxan. You can also call 800-222-1222 to reach America’s Poison Centers or use its online resource. But if you have severe symptoms, immediately call 911 (or your local emergency number) or go to the nearest emergency room.

The sections above describe the usual dosages provided by the drug’s manufacturer. If your doctor recommends Xifaxan for you, they’ll prescribe the dosage that’s right for you.

Remember, you should not change your dosage of Xifaxan without your doctor’s recommendation. Only take Xifaxan exactly as prescribed. Talk with your doctor if you have questions or concerns about your current dosage.

Here are some examples of questions you may want to ask your doctor:

  • Does my dosage of Xifaxan depend on other medications I take?
  • Will you change my dosage of Xifaxan if I develop Clostridioides (formerly Clostridium) difficile diarrhea during treatment?
  • Should my dosage change if Xifaxan isn’t working well enough for me?

To learn more about Xifaxan, see these articles:

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Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.