Xifaxan (rifaximin) is a brand-name tablet that’s prescribed for certain conditions caused by bacterial infection in the intestines. As with other drugs, Xifaxan can cause side effects. These include headache and nausea.

The Food and Drug Administration (FDA) has approved Xifaxan for:

Xifaxan belongs to a drug class called rifamycin antibiotics. The drug is not available in a generic version.

Read on to learn about potential common, mild, and serious side effects of Xifaxan. For a general overview of the drug, including details about its uses, see this article.

These are just a few of the more common side effects reported by people who took Xifaxan in clinical trials. These side effects can vary depending on which condition the drug is being taken to treat.

A common side effect in people taking Xifaxan for traveler’s diarrhea was a headache.*

More common side effects in people taking Xifaxan for irritable bowel syndrome with diarrhea (IBS-D) included nausea and elevated liver enzymes.

More common side effects in people taking Xifaxan for hepatic encephalopathy include:

* For more information about this side effect, see “Side effect specifics” below.

Mild side effects can occur with Xifaxan. These side effects may differ slightly depending on the condition being treated. This list doesn’t include all possible mild side effects of the drug. For more information, you can refer to Xifaxan’s prescribing information.

Mild side effects that have been reported with Xifaxan include:

These side effects may be temporary, lasting a few days to weeks. However, if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks side effects of the medication. If you develop a side effect while taking Xifaxan and want to tell the FDA about it, visit MedWatch.

* For more information about this side effect, see “Side effect specifics” below.
† An allergic reaction is possible after taking Xifaxan. However, this side effect wasn’t reported in clinical trials. To learn more, see the “Side effect specifics” section below.

Xifaxan may cause serious side effects. The list below may not include all possible serious side effects of the drug. For more information, you can refer to Xifaxan’s prescribing information.

If you develop serious side effects while taking Xifaxan, call your doctor right away. If the side effects seem life threatening or you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Serious side effects that have been reported and their symptoms include:

* For more information about this side effect, see “Side effect specifics” below.
† An allergic reaction is possible after taking Xifaxan. This side effect wasn’t reported in clinical trials but has been reported since the drug was approved. To learn more, see the “Side effect specifics” section below.

Xifaxan may cause several side effects. Here are some frequently asked questions about the drug’s side effects and their answers.

Can Xifaxan be prescribed for small intestinal bacterial overgrowth? If so, does taking the drug for this use cause certain side effects?

It’s possible for a doctor to prescribe Xifaxan for small intestinal bacterial overgrowth (SIBO). However, this is an off-label use of the drug. With off-label use, a drug is prescribed for a use that’s not approved by the Food and Drug Administration (FDA).

Xifaxan’s side effects when taken for SIBO are likely similar to its side effects when taken for its approved uses. However, there are no clinical trials of the drug’s side effects in people with SIBO. So it’s not known whether Xifaxan may cause different side effects in people with this condition.

To find out more about taking Xifaxan for SIBO, talk with your doctor.

Will I experience certain side effects after stopping Xifaxan?

It’s possible. Xifaxan can sometimes cause diarrhea related to Clostridioides difficile infection. This side effect can occur both during treatment and after you stop taking Xifaxan. In some cases, it can occur more than 2 months after stopping treatment.

If you have diarrhea after stopping treatment with Xifaxan, talk with your doctor as soon as possible. To read more about this side effect, see the “Side effect specifics” section below.

How long do side effects of Xifaxan typically last?

Xifaxan’s side effects typically go away within a few days or weeks.

If you have any persistent or bothersome side effects, talk with your doctor.

Does Xifaxan cause weight gain?

No, Xifaxan is not likely to cause weight gain. Weight gain wasn’t reported in clinical trials of the drug. However, Xifaxan may cause fluid buildup in some people. In turn, this can cause weight gain.

In clinical trials, peripheral edema and ascites were reported in some people who took Xifaxan for hepatic encephalopathy. Peripheral edema is fluid buildup that causes swelling in your hands, feet, ankles, or legs. Ascites is a buildup of fluid that causes swelling around your abdomen.

If you have weight gain or swelling while taking Xifaxan, talk with your doctor. They can help determine the possible cause. If necessary, they may prescribe treatment for fluid buildup.

Learn more about some of the side effects that Xifaxan may cause. To find out how often side effects occurred in clinical trials, see the prescribing information for Xifaxan.

Headache

Xifaxan can cause headaches in some people. In clinical trials, it was commonly reported in people who took Xifaxan for traveler’s diarrhea.

However, a headache can also be a symptom of dehydration, which diarrhea may cause.

What you can do

If you have a headache while taking Xifaxan, it will typically get better on its own within a few hours. You can help ease a headache by drinking plenty of fluids, getting some rest, and gently massaging your temples.

If you have a headache that’s severe or bothersome, talk with your doctor or pharmacist. They can recommend whether it’s safe to take an over-the-counter pain reliever with Xifaxan. Examples include Tylenol (acetaminophen) and Motrin (ibuprofen).

If you take Xifaxan for traveler’s diarrhea, drinking plenty of fluids can help prevent dehydration. It may also help to drink electrolyte drinks, such as rehydration solutions or sports drinks. These drinks replace necessary salts and fluids that you can lose with diarrhea.

Diarrhea caused by Clostridioides difficile infection

Xifaxan is an antibiotic that can change the typical levels of bacteria in your digestive system. Taking antibiotics can cause an increase in a bacterium called Clostridioides difficile (C. diff).As a result, it may cause an infection in your intestines. This can cause diarrhea that may be mild or severe.

In clinical trials of Xifaxan, this side effect was rare. However, it can occur in people who take Xifaxan for any condition.

Diarrhea caused by C. diff can occur during or after stopping treatment with Xifaxan. In some cases, this side effect has been reported more than 2 months after antibiotic treatment ended.

Symptoms of C.diff-related diarrhea can include:

What you can do

If you take Xifaxan for diarrhea, talk with your doctor if your diarrhea persists or worsens during treatment.

If you take Xifaxan for any condition, contact your doctor if you develop diarrhea after stopping treatment.

If you have this side effect, your doctor will likely prescribe antidiarrheal medication to treat it. They may also have you stop treatment with Xifaxan.

Dizziness

Some people may experience dizziness while taking Xifaxan. In clinical trials, this was commonly reported in people who took Xifaxan for hepatic encephalopathy.

Dizziness can also be a symptom of anemia (low red blood cell count), which is another possible side effect of Xifaxan. It may also result from dehydration, which can occur in people with diarrhea. Keep in mind that Xifaxan is prescribed to treat traveler’s diarrhea.

What you can do

If you feel dizzy while taking Xifaxan, sit or lie down until the feeling passes.

If you experience persistent or bothersome dizziness, talk with your doctor. They can help determine the cause.

If you take Xifaxan for diarrhea, it’s important to drink plenty of fluids. This replaces fluids lost through diarrhea and helps prevent dehydration, which can cause dizziness.

Nausea

It’s possible to experience nausea while taking Xifaxan. In clinical trials, nausea was commonly reported in people who took Xifaxan for hepatic encephalopathy or irritable bowel syndrome with diarrhea (IBS-D).

Note that nausea can also be a symptom of the conditions that Xifaxan treats.

What you can do

If you experience nausea while taking Xifaxan, it may help to:

  • take frequent sips of water
  • get plenty of fresh air
  • drink ginger or peppermint teas
  • avoid oily, sugary, or rich foods
  • eat smaller, more frequent meals instead of large main meals

If you have persistent or bothersome nausea during treatment, talk with your doctor. They may recommend other ways to manage this symptom.

Allergic reaction

As with most drugs, Xifaxan can cause an allergic reaction in some people. This side effect wasn’t reported in clinical trials, but it’s been reported since the drug was approved.

Symptoms can be mild or serious and can include:

  • skin rash
  • itching
  • flushing
  • swelling under your skin, typically in your eyelids, lips, hands, or feet
  • swelling of your mouth, tongue, or throat, which can make it hard to breathe

What you can do

For mild symptoms of an allergic reaction, call your doctor right away. They may recommend ways to ease your symptoms and determine whether you should keep taking Xifaxan. However, if your symptoms are serious and you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Be sure to talk with your doctor about your health history before you take Xifaxan. This drug may not be the right treatment option for you if you have certain medical conditions or other factors that affect your health. These are considered drug-condition or drug-factor interactions. The conditions and factors to consider include:

Allergic reaction. If you’ve had an allergic reaction to Xifaxan, any of its ingredients, or other similar antibiotics, your doctor will likely not prescribe Xifaxan. Ask your doctor what other medications may be better options for you.

Severe liver problems. Your liver is involved in breaking down Xifaxan that’s absorbed into your body. If you have severe liver problems, Xifaxan could build up in your body, which may raise your risk of side effects. If you have a severe liver problem, your doctor may monitor you more closely for side effects from Xifaxan.

Alcohol with Xifaxan

There are no known interactions between Xifaxan and alcohol. However, Xifaxan and alcohol can cause some of the same side effects, such as headache, nausea, and dizziness. If you drink alcohol with Xifaxan, you may be more likely to experience these side effects.

Keep in mind that drinking alcohol may also worsen symptoms of traveler’s diarrhea, irritable bowel syndrome with diarrhea (IBS-D), and hepatic encephalopathy. Xifaxan is prescribed to treat these conditions.

If you have questions about drinking alcohol while taking Xifaxan, talk with your doctor or pharmacist. You can also read this article about taking antibiotics with alcohol.

Pregnancy and breastfeeding while taking Xifaxan

It’s not known whether it’s safe to take Xifaxan during pregnancy or while breastfeeding. The drug hasn’t been clinically trialed in people who are pregnant or breastfeeding.

If you’re pregnant, breastfeeding, or planning for either, talk with your doctor before taking Xifaxan. They can advise on whether Xifaxan is right for you.

Side effects aren’t particularly common with Xifaxan. Most people take this medication without problems. Most side effects are mild and easily managed. The medication can cause some serious side effects, but these are rare.

If you’d like to learn more about Xifaxan, talk with your doctor or pharmacist. They can help answer any questions you have about side effects from taking the drug.

Besides talking with your doctor, you can do some research on your own. These articles might help:

Disclaimer: Medical News Today 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.