Xifaxan (rifaximin) is a prescription oral tablet that’s used to treat some types of diarrhea. It’s also used to lower certain risks in adults with specific liver problems.

Xifaxan is used to:

To learn more about Xifaxan’s uses, see the “What is Xifaxan used for?” section below.

Xifaxan basics

Xifaxan contains the active ingredient rifaximin. (An active ingredient is what makes a drug work.) It belongs to a group of drugs called antibiotics.

Xifaxan is a brand-name medication that isn’t available as a generic drug.

Your doctor will recommend the dosage of Xifaxan that’s right for you. Below are commonly used dosages, but always take the dosage your doctor prescribes.

Form

Xifaxan comes as an oral tablet.

Strengths: 200 mg and 550 mg

Xifaxan tablets are available in two strengths: 200 milligrams (mg) and 550 mg.

Recommended dosages

The recommended dosages for Xifaxan are described below, based on the condition the drug is used to treat.

Dosage for irritable bowel syndrome with diarrhea (IBS-D)

For treating IBS-D, you’ll likely take one 550-mg Xifaxan tablet three times per day. You’ll take this dosage for 14 days.

If your symptoms return, you may repeat this treatment cycle up to two times.

Dosage for hepatic encephalopathy

For lowering the risk of hepatic encephalopathy, you’ll likely take one 550-mg Xifaxan tablet twice per day for as long as your doctor prescribes.

Dosage for traveler’s diarrhea

For treating traveler’s diarrhea, you’ll likely take one 200-mg Xifaxan tablet three times per day for three days.

To learn more about Xifaxan’s dosage, see this article.

Questions about taking Xifaxan

Below are some common questions about taking Xifaxan.

  • Can Xifaxan be chewed, crushed, or split? The drug’s manufacturer hasn’t stated whether Xifaxan can be chewed, crushed, or split. If you’re having trouble swallowing pills, talk with your doctor or pharmacist about your options.
  • Should I take Xifaxan with food? You may take Xifaxan with or without food.
  • Is there a best time of day to take Xifaxan? No, there’s no one best time of day to take Xifaxan. Take your doses according to your doctor’s instructions.
  • What if I miss a dose of Xifaxan? If you miss a Xifaxan dose, take it as soon as you remember. But if it’s nearly time for your next dose, skip the missed dose and take your next dose at its usual time. You should not take more than one dose of Xifaxan at once to make up for a missed dose.
  • Will I need to use Xifaxan long term? It’s possible, depending on the condition you take Xifaxan to treat. Xifaxan is used short term for IBS-D and traveler’s diarrhea, but it’s typically used long term to lower the risk of hepatic encephalopathy.

Overdose

Do not take more Xifaxan than your doctor prescribes. For some drugs, using more than this can lead to negative effects.

What to do in case you take too much Xifaxan

Call your doctor 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.

Like most drugs, Xifaxan may cause mild or serious side effects. The lists below describe some of the more common side effects that Xifaxan may cause. These lists don’t include all possible side effects.

Keep in mind that side effects of a drug can depend on:

  • your age
  • other health conditions you have
  • other medications you take

Your doctor or pharmacist can tell you more about the potential side effects of Xifaxan. They can also suggest ways to help reduce side effects.

Mild side effects

Here’s a list of some of the mild side effects that Xifaxan can cause. To learn about other mild side effects, talk with your doctor or pharmacist, or read Xifaxan’s prescribing information.

Mild side effects of Xifaxan that have been reported include:

Mild side effects of many drugs may go away within a few days to a couple of weeks. But if they become bothersome, talk with your doctor or pharmacist.

* To learn more about this side effect, see the “Allergic reaction” section below.

Serious side effects

Serious side effects from Xifaxan can occur, but they aren’t common. If you have serious side effects from Xifaxan, call your doctor right away. But if you think you’re having a medical emergency, you should call 911 or your local emergency number.

Serious side effects of Xifaxan that have been reported include:

  • Clostridioides difficile (C. diff) infection and associated severe diarrhea
  • severe skin reactions, including Stevens-Johnson syndrome
  • severe allergic reaction*

* To learn more about this side effect, see the “Allergic reaction” section below.

Allergic reaction

Some people may have an allergic reaction to Xifaxan. These reactions weren’t reported in studies of Xifaxan but have happened since the drug was approved.

Symptoms of a mild allergic reaction can include:

A more severe allergic reaction is rare but possible. Symptoms of a severe allergic reaction can include swelling under your skin, usually in your eyelids, lips, hands, or feet. They can also include swelling of your tongue, mouth, or throat, which can cause trouble breathing.

Call your doctor right away if you have an allergic reaction to Xifaxan. But if you think you’re having a medical emergency, call 911 or your local emergency number.

Xifaxan is used to:

  • Treat traveler’s diarrhea caused by certain forms of the bacteria Escherichia coli (E. coli).The drug can be used for this purpose in adults and in children ages 12 years and older. With traveler’s diarrhea, you have abdominal cramps and diarrhea usually caused by consuming food or water that your body isn’t familiar with.
  • Treat irritable bowel syndrome with diarrhea (IBS-D) in adults. With IBS-D, the main symptoms are loose stools and sudden urges to have a bowel movement.
  • Lower the risk of developing overt* hepatic encephalopathy episodes in adults with severe liver disease. Hepatic encephalopathy is a condition related to severe liver disease that causes a decline in brain function that may be short or long term.

To learn more about the drug’s uses for these conditions, talk with your doctor or pharmacist.

* “Overt” means the condition causes severe and noticeable symptoms.

Below is important information you should consider before taking Xifaxan.

Interactions

Taking a drug with certain medications, vaccines, foods, and other things can affect how the drug works. These effects are called interactions.

Xifaxan can interact with several other medications. It can also interact with certain supplements as well as certain foods.

Before taking Xifaxan, talk with your doctor and pharmacist. Tell them about all prescription, over-the-counter, and other drugs you take. Also tell them about any vitamins, herbs, and supplements you use. Sharing this information can help you avoid potential interactions.

Drug interactions

Below is a list of medications that can interact with Xifaxan. This list does not contain all drugs that may interact with Xifaxan. If you have questions about drug interactions that may affect you, ask your doctor or pharmacist.

Drug group or drug nameDrug examples
drugs that block the activity of a protein that helps your body get rid of Xifaxan • cyclosporine (Gengraf, Neoral, Sandimmune)
• ketoconazole
warfarin (Jantoven) –

Xifaxan and alcohol

Alcohol is not known to interact with Xifaxan. It’s likely safe to consume alcohol while taking Xifaxan.

However, alcohol may interact with a condition you’re using Xifaxan to treat. For example, alcohol could worsen symptoms of traveler’s diarrhea or hepatic encephalopathy.

If you drink alcohol, talk with your doctor about how much (if any) may be safe to consume with your condition.

Pregnancy and breastfeeding

It’s not known whether Xifaxan is safe to take while pregnant or breastfeeding.

If you’re pregnant or breastfeeding, or planning to become pregnant or breastfeed, talk with your doctor before taking Xifaxan.

Warnings

Xifaxan can sometimes cause harmful effects in people who have certain conditions. This is known as a drug-condition interaction. Other factors may also affect whether Xifaxan is a good treatment option for you.

Talk with your doctor about your health history before you take Xifaxan. Be sure to tell them if any of the following factors apply to you:

Whether you have health insurance or not, cost may be a factor when you’re considering Xifaxan. What you’ll pay for Xifaxan may depend on several things, such as your treatment plan and the pharmacy you use.

Here are a few things to consider regarding cost:

  • Cost information and savings coupons: You can visit Optum Perks* to get price estimates of what you’d pay for Xifaxan when using coupons from the site.
  • Savings program: If you have questions about how to pay for your prescription, talk with your doctor or pharmacist. An Instant Savings Card may also be available.

You can also check out this article to learn more about saving money on prescriptions.

* Optum Perks is a sister site of Healthline. Optum Perks coupons cannot be used with any insurance copays or benefits.

Other drugs are available that can treat your condition. If you’d like to explore an alternative to Xifaxan, talk with your doctor. They can tell you about other medications that might work well for you.

The following drugs are similar to Xifaxan:

Find answers to some commonly asked questions about Xifaxan.

Is Xifaxan used for small intestinal bacterial overgrowth (SIBO)?

Xifaxan is not approved to treat SIBO. However, in some cases, 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.)

Some research has shown Xifaxan to be effective for treating SIBO symptoms.

If you have questions about treatment options for SIBO, including Xifaxan, talk with your doctor.

Can Xifaxan cause constipation or weight gain?

It’s not likely. Neither constipation nor weight gain were reported as side effects in studies of Xifaxan.

Other treatments for diarrhea may cause constipation, such as loperamide (Imodium A-D) or alosetron (Lotronex). But Xifaxan should not cause these side effects.

Weight gain isn’t unusual in people with hepatic encephalopathy, especially when the condition is chronic (long term). Symptoms of hepatic encephalopathy, such as confusion, drowsiness, or fatigue (low energy), may make it difficult to exercise. But Xifaxan itself isn’t expected to cause weight gain.

If you experience constipation or weight gain that concerns you, talk with your doctor.

How does Xifaxan work?

Xifaxan is an antibiotic drug. It works by preventing bacteria from making proteins needed for the bacteria to grow and spread in your body.

With hepatic encephalopathy, certain bacteria produce ammonia that gets into your brain and causes symptoms. Xifaxan works by killing ammonia-producing bacteria.

Xifaxan works to treat traveler’s diarrhea by killing bacteria brought into your body from exposure to food or water your body isn’t familiar with.

It’s not fully understood how Xifaxan works to treat irritable bowel syndrome with diarrhea (IBS-D). The cause of IBS-D also isn’t currently known. Some research shows that changes to the type or amount of bacteria typically present in your gut may lead to IBS-D symptoms. Xifaxan may work by killing “bad” bacteria in the gut, helping rebalance the levels of “good” bacteria present.

If you have other questions about how Xifaxan works to treat your condition, talk with your doctor or pharmacist.

If you have questions about taking Xifaxan, talk with your doctor or pharmacist. Questions you may want to ask include:

  • How will we monitor whether Xifaxan is working to treat my condition?
  • Does Xifaxan interact with any medications I take?
  • Should I let you know if I make changes to my lifestyle or diet while I’m taking Xifaxan?
  • How does Xifaxan compare with other treatments for my condition?

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.