JASMA

Vowst (fecal microbiota spores, live-brpk) is one of the newest kids on the gut-health block. It’s an oral microbiome therapy designed to help
prevent recurrent Clostridioides difficile (C. diff) infection in adults after they’ve already finished antibiotics for a recurrence. It’s not an antibiotic, and it doesn’t treat an active infection instead, it helps repopulate your gut with healthier bacteria so C. diff has a harder time coming back.

Sounds great… until you read the phrase “made from human fecal matter.” At that point, most people have at least two questions:
“Is this safe?” and “What kind of side effects am I signing up for?”

This guide walks you through the common Vowst side effects, rarer but serious risks, and practical steps you can take to manage them. We’ll keep it clear, evidence-based, and just light enough that you don’t feel like you’re reading a textbook while your gut is auditioning new bacteria.

How Vowst Works (and Why Side Effects Happen)

Vowst is a live biotherapeutic product. Each capsule contains purified bacterial spores derived from carefully screened stool donors. These spores make their way to your intestines and help rebuild a healthier microbiome after antibiotics, lowering the odds that C. diff overgrows again.

The standard regimen is:

• Finish your antibiotic treatment for recurrent C. diff.
• Do a bowel prep (usually magnesium citrate) the day before your first dose.
• Take 4 capsules once daily for 3 consecutive days, on an empty stomach before your first meal.

Any time you rearrange the gut microbiome, your digestive system may complain a little. That’s where most of the Vowst side effects come from: your intestines reacting to new bacterial “roommates,” plus the lingering effects of recent antibiotics and bowel prep.

1. Abdominal Bloating and Discomfort

Bloating or abdominal distension is the most commonly reported side effect, affecting about a third of people in trials. People describe it as feeling “puffy,” “full of air,” or like their waistband suddenly got tighter.

What you can do

• Eat smaller, more frequent meals instead of big, heavy ones.
• Limit gas-triggering foods short-term (beans, carbonated drinks, very greasy foods), especially in the first week after taking Vowst.
• Gentle movement like walking can help your gut move gas along.
• If your doctor says it’s safe, they may suggest an over-the-counter gas-relief product (for example, simethicone) or antacid to ease discomfort.

Call your healthcare professional if bloating becomes very painful, is associated with severe cramping, or you can’t pass gas or stool those can be signs of a more serious issue, not a typical Vowst reaction.

2. Fatigue

Fatigue is also common with Vowst. But remember: many people taking Vowst have recently battled recurrent C. diff, gone through multiple rounds of antibiotics, and done a bowel prep. That alone can leave anyone wiped out. Trials reported fatigue in about 1 in 5 patients.

What you can do

• Respect the nap. Plan for a slightly lighter schedule during and shortly after your 3-day Vowst course.
• Stay hydrated and eat balanced meals with protein and complex carbs to support your recovery.
• Try short, gentle activity (like a 5–10 minute walk) once or twice a day, if your doctor agrees it can actually help counter fatigue.

If fatigue is severe, sudden, or worsening especially if you also have fever, shortness of breath, or chest pain seek medical care promptly.

3. Constipation

Constipation showed up in around 14% of people receiving Vowst in trials. That might feel ironic if you’ve just had weeks of diarrhea, but remember: your gut motility is recalibrating after infection, antibiotics, bowel prep, and now microbiome therapy.

What you can do

• Hydrate consistently. Aim for water or oral rehydration solutions unless your doctor has given you fluid restrictions.
• If your healthcare professional gives the go-ahead, gradually add fiber-rich foods (oats, fruits, vegetables) once your gut has settled from C. diff.
• Short, frequent walks can stimulate bowel activity.
• Your doctor or pharmacist may recommend a gentle stool softener or osmotic laxative if needed always check before starting anything new.

Call your doctor if constipation lasts more than a few days, is severe, or comes with intense abdominal pain or vomiting.

4. Chills

Some people report feeling chilled or shivery during the first week after taking Vowst. In trials, chills occurred in a little over 10% of participants.

What you can do

• Monitor your temperature. Chills without a fever for a short time can be a mild side effect.
• Dress in layers and keep a blanket handy while this passes.

However, if you have chills with a fever, severe abdominal pain, bloody stools, confusion, or feel acutely ill, treat that as an urgent situation and contact your doctor or local emergency services. That may signal infection rather than a simple medication side effect.

5. Diarrhea

Diarrhea is a tricky one, because it’s both a symptom of C. diff and a listed side effect of Vowst. In trials, diarrhea occurred in about 10% of those taking Vowst, and these episodes were typically short-lived (around five days or less).

What you can do

• Focus on hydration water, broths, or an oral rehydration solution. Dehydration is the main danger of diarrhea.
• Eat bland foods if tolerated (bananas, rice, toast, applesauce) as your gut settles.
• Do not start anti-diarrheal drugs (like loperamide) without checking with your clinician, especially with a history of C. diff.

Call your healthcare professional right away if:

• You have three or more watery stools per day for more than two days, especially if there’s mucus or blood.
• You have fever, severe abdominal pain, or signs of dehydration (dizziness, dry mouth, dark urine).

Mild vs Serious Side Effects

Most Vowst side effects fall into the “annoying but manageable” category: bloating, gas, mild nausea, constipation, diarrhea, chills, and fatigue. These usually resolve on their own within a few days.

Serious side effects appear to be rare, but you still need to know what to watch for.

1. Allergic Reactions

Allergic reactions weren’t reported in Vowst clinical trials, but like almost any biologic product, they’re still possible.

Seek emergency care immediately if you develop:

• Hives, widespread rash, or intense itching
• Swelling of the face, lips, tongue, or throat
• Trouble breathing, wheezing, or chest tightness
• Dizziness, fainting, or a feeling of “impending doom”

2. Infection Risk from Donor Material

Because Vowst is manufactured from human stool, there is a theoretical risk of transmitting infectious agents, even though donors are carefully screened and the product undergoes additional processing to reduce pathogens.

Contact your healthcare professional right away if, after Vowst, you develop:

• High fever or shaking chills
• Severe abdominal pain
• Bloody diarrhea
• Signs of sepsis (fast heart rate, confusion, extreme weakness)

These are not typical Vowst side effects and need urgent evaluation. If an infection is suspected to be related to Vowst, your healthcare professional may report it to the manufacturer or the FDA’s MedWatch system.

Who Needs Extra Caution with Vowst?

Before you start Vowst, your healthcare professional will review your overall health to see if there are specific concerns.

• Immunocompromised individuals. People with weakened immune systems (for example, due to certain medications, cancers, or transplants) were included in some trials, but they may have a higher baseline risk from infections in general. Extra monitoring is important.
• Severe kidney disease. Some people with kidney problems may not be able to safely use magnesium citrate for bowel prep and may require alternative regimens.
• Food allergies. Vowst may contain trace food allergens because it’s derived from donor stool. The potential for a reaction from food allergens in the product is unknown, so let your clinician know if you have severe food allergies.
• Pregnancy and breastfeeding. There are limited data on Vowst in pregnant or breastfeeding people. Your clinician will weigh the risks of C. diff recurrence against the uncertainties of using a new microbiome therapy during this time.

Always tell your care team about every medication and supplement you use prescription, over-the-counter, vitamins, and herbal products.

Drug Interactions: Why You Shouldn’t Take Vowst with Antibiotics

One of the most important safety points is that antibacterial drugs should not be given at the same time as Vowst. Vowst contains live bacterial spores; antibiotics could kill or disrupt them and reduce how well the treatment works.

In practice, that means:

• You complete your antibiotic course for recurrent C. diff first.
• You then start Vowst 2–4 days after finishing antibiotics, following your clinician’s instructions.
• If another infection pops up and your clinician believes you need antibiotics again, they’ll decide how to handle the timing relative to Vowst.

How Long Do Vowst Side Effects Last?

In clinical studies, most side effects like bloating, constipation, fatigue, chills, and diarrhea lasted five days or less. Some people had no noticeable side effects at all.

However, everyone’s situation is different. You’ve just gone through an intestinal infection plus antibiotics and bowel prep, so it can be hard to separate “Vowst side effects” from “my gut is still recovering.” The safest rule is:
if something feels severe, prolonged, or just wrong, call your healthcare professional.

Everyday Tips for Managing Vowst Side Effects

• Follow dosing instructions exactly. Take all 4 capsules each day for 3 days, on an empty stomach before your first meal, unless your clinician tells you otherwise.
• Don’t crush or chew the capsules. Swallow them whole so they release where they’re supposed to in your gut.
• Plan for a quieter week. Mild bloating, extra bathroom trips, or feeling tired are easier to tolerate when your schedule isn’t packed.
• Keep a simple symptom diary. Note when you started Vowst, any side effects, and when they improve. This is very helpful for your clinician if questions come up.
• Ask about rescue plans. Before starting, ask your clinician: “If I get diarrhea or abdominal pain again, when should I call you versus go straight to the ER?”

Remember: never stop, restart, or replace Vowst on your own. Always involve your healthcare professional in those decisions.

Real-World Experiences with Vowst: What People Report

The stories below are composite examples based on patterns described in clinical studies and real-world reports not actual individual patients. They’re here to give you a feel for what the Vowst experience can be like.

“Maria,” 62 – Bloating but Big Relief

Maria had been through C. diff three times. She knew the routine: antibiotics, a brief calm period, then the creeping worry every time her stomach gurgled. When her gastroenterologist suggested Vowst, the phrase “capsules made from healthy donor stool” almost made her say no. But the idea of yet another C. diff recurrence bothered her more.

During her three days of Vowst, she had noticeable bloating and fatigue. Her jeans felt snug, and she took more naps than usual. She stuck to small meals, drank plenty of water, and walked around her house every couple of hours. Her doctor reassured her these were expected, short-term effects.

By day five after starting Vowst, the bloating had eased. Most importantly, the weeks that followed looked completely different from her earlier pattern no waves of watery diarrhea, no frantic calls to the clinic. For Maria, a few days of feeling puffy and tired felt like a trade-off she’d absolutely make again.

“Tom,” 48 – Constipation and Anxiety

Tom’s C. diff story started after a routine surgery and a heavy course of antibiotics. He’d always had an unpredictable gut, so the idea of a microbiome therapy made sense to him but he still worried about side effects. After finishing antibiotics, he did the magnesium citrate prep and started his three days of Vowst.

Instead of diarrhea, Tom developed constipation and mild cramping. When you’ve recently had C. diff, any change in bowel habits can trigger anxiety. He tracked his symptoms in a notebook, called his GI clinic, and was reassured that mild constipation can occur and is usually temporary.

With guidance, he increased fluids, added more soluble fiber to his diet, and walked daily. Within a few days, things moved again slowly but steadily. The bigger picture became clear a few weeks later: no rushing to the bathroom 8–10 times a day, no fear of leaving the house. For Tom, careful symptom tracking plus a low threshold to call his clinician helped him ride out the uncomfortable part.

“Janelle,” 71 – Tired but Finally Sleeping

Janelle had multiple health issues, including diabetes and heart disease. She was understandably nervous about a product made from donor stool, especially given her age and medications. Her infectious disease specialist went over the data with her and emphasized that C. diff recurrence itself was a big threat to her health and independence.

Janelle’s main side effect was fatigue and mild chills for several days after starting Vowst. She checked her temperature twice a day and never developed a fever. Her care team had already discussed red-flag symptoms, so she knew exactly when she’d need to call.

The surprising part for her came a month later. For the first time in a long time, she slept through the night without waking to run to the bathroom. She told her daughter, “I’m more tired for a few days, but I’m less exhausted by fear.” For many people, that’s the real impact of Vowst: not just fewer C. diff recurrences, but less emotional and practical disruption.

What These Experiences Have in Common

While every person is different, some themes show up again and again:

• Side effects tend to be short-term usually days, not weeks.
• They’re mostly digestive and low-grade systemic symptoms like bloating, mild diarrhea or constipation, chills, and fatigue.
• Clear communication with the care team makes a huge difference in comfort and confidence.
• For many people, the short-term side effects feel more manageable than repeated recurrences of C. diff and repeated rounds of antibiotics.

The bottom line: Vowst won’t make the gut recovery process glamorous, but for many adults at high risk for recurrent C. diff, its side effects are generally manageable and often temporary and the potential benefit of breaking the recurrence cycle can be life-changing.

Final Thoughts: Balancing Risks, Side Effects, and Benefits

No medication is completely free of side effects, and that includes Vowst. The good news is that, based on current evidence, most Vowst side effects are mild to moderate and short-lived, often resolving within a few days. The major concerns infection transmission and allergic reactions appear rare but still deserve respect and careful monitoring.

If you’re considering Vowst, talk with your healthcare professional about:

• Your past C. diff history and recurrence risk
• Your other medical conditions and medications
• What side effects you personally worry about most
• What to do and who to call if symptoms appear

Think of this conversation as a shared decision-making session: you bring your values and concerns; your clinician brings the data and experience. Together, you can decide whether the benefit of reducing C. diff recurrence outweighs the relatively short-term side effect profile of Vowst for you.

Important: This article is for general information only and is not medical advice. Always talk to your own doctor, pharmacist, or other qualified health professional about your specific situation.