Vowst is a brand-name oral capsule that’s prescribed to help prevent Clostridioides difficile (C. diff) infection from coming back. Vowst contains live fecal microbiota spores as its active ingredient.

The Food and Drug Administration (FDA) has approved Vowst for use in adults to help prevent C. diff infection from coming back (recurring). It’s prescribed for people who have already received antibiotic treatment for a recurrent C. diff infection.

Drug details

You’ll find key information about Vowst below.

  • Drug class: microbiome therapy, which is a type of fecal microbiota transplant
  • Drug form: oral capsule
  • Generic or biosimilar available? no
  • Prescription required? yes
  • Controlled substance? no
  • Year of FDA approval: 2023

Vowst is a brand-name biologic drug. The active ingredient is fecal microbiota spores, live-brpk. (The reason “-brpk” appears at the end of the drug’s name is to show that the drug is distinct from similar medications that may be created in the future.) Vowst is not currently available in a biosimilar version.

Biologic drugs are made from living cells. Traditional (nonbiologic) drugs are usually made from chemicals. A generic is an exact copy of the active ingredient in a traditional brand-name medication. Since it’s not possible to make an exact copy of a biologic drug’s active ingredient, they have biosimilars. A biosimilar is a biological medication that’s similar to the original biologic drug (the parent drug) that’s already been approved by the Food and Drug Administration (FDA).

Biosimilars are considered to be just as safe and effective as their parent drug. And like generics, biosimilars usually cost less than brand-name biologic drugs.

To learn more about this drug’s active ingredient, see “How does Vowst work?” in the “Common questions about Vowst” section below.

The following information describes dosages that are commonly prescribed or recommended. However, be sure to take the dosage your doctor prescribes for you. Your doctor will determine the best dosage to fit your needs.

Drug form

Vowst comes as an oral capsule that you swallow.

Dosage for prevention of recurrent C. diff infection

Doctors may prescribe Vowst to help prevent Clostridioides difficile (C. diff) infection from coming back (recurring) following antibiotic treatment for a recurrent C. diff infection. For details about this, see the “Vowst uses” section below.

The recommended dosage is four capsules taken once daily for 3 days in a row.

About taking Vowst

You should take Vowst exactly as your doctor prescribes. Before you start treatment with Vowst, your doctor will discuss the following:

  • Finish your antibiotic treatment: You’ll take your last dose of antibiotic 2–4 days before starting Vowst.
  • Take a laxative: You’ll drink a laxative at least 8 hours before your first dose of Vowst. Your doctor will likely recommend:
    • 10 ounces (oz) of magnesium citrate or
    • 250 milliliters (mL) of polyethylene glycol electrolyte solution
  • Fast: Do not eat or drink anything except a small amount of water for at least 8 hours before you start taking Vowst and before each dose.

Below you’ll find information about other key dosage issues:

  • When to take: You should take Vowst before your first meal of the day. Taking the medication on an empty stomach helps Vowst work effectively.
  • Vowst and food: You’ll take Vowst on an empty stomach before your first meal of the day. Before your first dose, you should not eat for at least 8 hours. You may drink a small amount of water.
  • If you miss a dose: If you miss a dose, talk with your doctor. They’ll advise you about what you should do.
  • Crushing, splitting, or chewing Vowst: You swallow Vowst capsules whole with water. You should not open or alter Vowst capsules in any way.
  • Length of use: Vowst is a short-term treatment. You’ll take the drug 3 days in a row.

If you have questions about taking Vowst, talk with your doctor or pharmacist. You can also view step-by-step instructions on the manufacturer’s website.

Overdose

Do not take more Vowst than your doctor recommends. For some drugs, doing so may lead to unwanted side effects or overdose.

What to do in case you take too much Vowst

If you think you’ve taken too much of this drug, call your doctor. You can also call America’s Poison Centers at 800-222-1222 or use its online tool. However, if your symptoms are severe, call 911 or your local emergency number, or go to the nearest emergency room right away.

Vowst can cause mild or serious side effects. The following lists contain some of the key side effects that may occur while taking Vowst. These lists do not include all possible side effects.

For more information about the possible side effects of Vowst, talk with your doctor or pharmacist. They can give you tips on how to manage any side effects that may be concerning or bothersome.

Note: The Food and Drug Administration (FDA) tracks side effects of drugs it has approved. If you’d like to notify the FDA about a side effect you’ve had with Vowst, you can do so through MedWatch.

Mild side effects

Below is a partial list of mild side effects of Vowst. To learn about other mild side effects, talk with your doctor or pharmacist, or view the drug’s prescribing information.

Mild side effects of Vowst can include:

Most of these side effects may go away within a few days to a couple of weeks. However, if they become more severe or don’t go away, talk with your doctor or pharmacist.

Serious side effects

No serious side effects have been reported with Vowst. Call your doctor right away if you’re experiencing side effects that seem severe. Call 911 or your local emergency number if your symptoms feel life threatening or if you think you’re having a medical emergency.

As with most drugs, a severe allergic reaction is possible.

ALLERGIC REACTION

As with most drugs, some people can have an allergic reaction after taking Vowst. This side effect wasn’t reported in clinical trials of this drug, but can still occur.

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, typically in your eyelids, lips, hands, or feet
  • swelling of your tongue, mouth, or throat
  • trouble breathing

Call your doctor right away if you have an allergic reaction to Vowst, as the reaction could become severe. Call 911 or your local emergency number if your symptoms feel life threatening or if you think you’re having a medical emergency.

The Food and Drug Administration (FDA) approves prescription drugs such as Vowst to treat certain conditions. Vowst may also be used off-label for other conditions. Off-label drug use is when an FDA-approved drug is prescribed for a purpose other than what it’s approved for.

Vowst for prevention of recurrent C. diff infection

Vowst is FDA-approved to help prevent Clostridioides difficile (C. diff) infection from coming back (recurring). Vowst is prescribed specifically for adults who have already received antibiotics to treat a recurrent C. diff infection.

C. diff is a bacterium that can cause an infection in your gut. The infection causes painful swelling in the lining of the large intestine (colon), also known as colitis. Symptoms of C. diff colitis may include:

C. diff infection is typically treated with antibiotics but the infection can return. About 1 in 6 people get it again within 2 months, according to the Centers for Disease Control and Prevention (CDC).

Note: Vowst is not used to treat C. diff infection. Doctors prescribe it to help prevent C. diff infection from coming back after antibiotic treatment.

Vowst and children

Vowst is only FDA-approved for use in adults. It’s not known whether this medication is safe or effective for people younger than 18 years.

Vowst can interact with certain other medications. It can also interact with food.

Before taking Vowst, 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.

Interactions with medications, foods, and supplements

Medications, supplements, and foods that can interact with Vowst are described below. This section does not describe all drugs that can interact with Vowst. For example, new drugs could be approved that interact with Vowst. If you have questions about drug interactions that may affect you, ask your doctor or pharmacist.

Interactions with antibiotics or antibacterial drugs

Vowst contains living bacterial cells called spores. It’s important not to take Vowst with antibiotics or other medications that kill bacteria. Taking such a drug with Vowst could make Vowst less effective in helping prevent C. diff infection.

Vowst is approved for use in people who have recently finished antibiotic treatment for a recurrent C. diff infection. However, your last dose of C. diff antibiotic will be at least 2–4 days before your first dose of Vowst.

Taking Vowst after you finish your antibiotic treatment helps Vowst work effectively. For details about how to take this drug, see the “Vowst dosage” section above.

Examples of antibiotics and antibacterial drugs include:

Interactions with food, vitamins, and supplements

It’s not known whether certain foods, vitamins, or supplements interact with Vowst. The drug’s manufacturer didn’t look at these interactions in clinical trials.

However, you should not eat any food for at least 8 hours before starting Vowst. You’ll take Vowst on an empty stomach before your first meal of the day. It’s best to avoid taking vitamins or supplements for at least 8 hours before starting Vowst.

If you have questions about taking supplements, other medications, or consuming certain foods during Vowst treatment, talk with your doctor or pharmacist.

Alcohol interaction

If you drink alcohol, your doctor will probably recommend avoiding it while taking Vowst. This is because it isn’t known whether alcohol interacts with Vowst. In addition, alcohol and Vowst may cause some of the same side effects, such as nausea.

You should not eat or drink anything (except small amounts of water) for at least 8 hours before starting Vowst.

If you have questions about when you can safely consume alcohol after completing Vowst treatment, talk with your doctor or pharmacist.

As with all medications, the cost of Vowst can vary. The actual price you’ll pay depends on your insurance plan and your location.

Financial and insurance assistance: If you need financial support to pay for Vowst or help to understand your insurance coverage, help is available.

A program called Vowst Voyage is available for Vowst. For more information and to find out whether you’re eligible for support, call 888-356-5444 or visit the program website.

Biosimilar version: Vowst is a biologic drug and it’s not available in a biosimilar form. Biosimilars tend to cost less than brand-name medications.

To learn more about saving money on prescriptions, read this article.

Other drugs are available that can treat or help prevent your condition. Some may be a better fit for you than others. If you’re interested in finding an alternative to Vowst, talk with your doctor. They can tell you about other medications that may work well for you.

Rebyota (fecal microbiota, live-jslm) is similar to Vowst. (The reason “-jslm” appears at the end of the drug’s name is to show that the drug is distinct from similar medications that may be created in the future.) To learn more, see “Is Vowst similar to Rebyota?” in the “Common questions about Vowst” section below.

If you can become pregnant, consider the following information about pregnancy, birth control, and breastfeeding.

Vowst and pregnancy

It’s not known whether Vowst should be taken during pregnancy. If you’re planning a pregnancy or can become pregnant, talk with your doctor before taking this medication.

Vowst and birth control

It’s not known whether Vowst is safe to take during pregnancy. If you’re sexually active and you or your partner can become pregnant, talk with your doctor about your birth control needs while you’re taking Vowst.

Vowst and breastfeeding

It’s not known whether Vowst should be taken while breastfeeding. If you’re currently breastfeeding or planning to do so, talk with your doctor before taking this medication.

Here are answers to some frequently asked questions about Vowst.

How does Vowst work?

Vowst is a type of fecal microbiota transplant (FMT). With FMT, bacteria from the gut (gut microbiota) of a healthy donor are transferred to the gut of a person with a recurrent Clostridioides difficile (C. diff) infection. The goal is to restore healthy intestinal flora (also known as “good” bacteria that live in the intestines) in the recipient. The “good” bacteria can help prevent C. diff from coming back.

Vowst is an oral capsule that contains bacterial spores. (A spore is a special type of bacterial cell.) The spores come from human fecal matter (stool) from healthy donors. The manufacturer uses a special purification process to remove germs and waste, leaving only the bacterial spores.

If you’d like to know more about how Vowst works, talk with your doctor or pharmacist.

Can Vowst cause long-term side effects?

Possibly, but no serious long-term side effects have been reported with Vowst. Most side effects, such as bloating and fatigue, last only a short time. Typically, they occur within 10 days of starting Vowst treatment. (Keep in mind that you’ll take Vowst for 3 days in a row.)

People taking the drug in clinical trials were monitored for 2–6 months after taking Vowst. There were no reports of long-term or severe side effects during this time.

The drug’s manufacturer states there’s a chance Vowst may carry germs that cause infection. This is because the medication is made from human fecal matter. However, there have been no reports of transmitted infections by people who have taken Vowst.

Talk with your doctor or pharmacist if you have questions about side effects or risks with Vowst. You can also refer to the “Vowst side effects” section above.

Is Vowst similar to Rebyota?

Yes, similar to Vowst, Rebyota (fecal microbiota, live-jslm) is made from human fecal matter from healthy donors. Both medications are a type of FMT. (See “How does Vowst work?” just above for details about FMT.)

Like Vowst, the Food and Drug Administration (FDA) has approved Rebyota to help prevent a recurrence of C. diff infection in certain adults.

However, the form and dosage of these drugs are different. While Vowst comes as an oral capsule that you swallow, Rebyota comes as a liquid suspension that’s administered rectally by a healthcare professional. Vowst is a 3-day treatment and Rebyota is a single-dose treatment. (See the “Vowst dosage” section above for details about taking Vowst.)

Talk with your doctor for more details and to help decide whether one of these medications may be an option for you.

This drug comes with several precautions.

Before taking Vowst, discuss your health history with your doctor. Vowst may not be right for you if you have certain medical conditions or other factors affecting your health. Be sure to talk with your doctor if any of the following apply to you:

Note: For more information about the potential negative effects of Vowst, see the “Vowst side effects” section above.

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.