Saccharomyces boulardii

Beneficial probiotic yeast that supports digestive health, prevents antibiotic-associated diarrhea, and enhances immune function with unique resistance to antibiotics

Scientific nameSaccharomyces boulardii FormulaLive yeast organism Molecular weightN/A - Living yeast organism g/mol CASN/A - Probiotic yeast strain

80 absorption score

9 safety / 10

40 USD per month

6 documented interactions

Check it against something

Evidence level B

Saccharomyces boulardii with:

78 out of 100

Works better together Compatible. Timing differs, so follow each supplement's own window.

Check it against your whole stack →

What it does

mechanism and evidence for each claim

Prevention of antibiotic-associated diarrhea

Clinically proven to prevent diarrhea during and after antibiotic treatment

Maintains gut microbiome balance and competes with harmful pathogens Evidence A-grade 1-2 weeks during antibiotic treatment

Protection against C. difficile infections

Reduces risk of C. difficile-associated diarrhea and recurrence

Produces compounds that inhibit C. difficile growth and toxins Evidence A-grade During and after antibiotic treatment

Enhanced immune system function

Strengthens immune response and reduces infection susceptibility

Stimulates immune cell activity and antibody production Evidence A-grade 2-8 weeks of consistent use

Improved digestive health and gut barrier

Strengthens intestinal barrier and reduces digestive inflammation

Produces beneficial metabolites and reinforces gut lining Evidence A-grade 2-6 weeks of regular supplementation

Antibiotic resistance for continuous protection

Survives antibiotic treatments maintaining probiotic benefits

Natural antibiotic resistance allows survival during treatment Evidence A-grade Immediate protection during antibiotic use

Others take these for the same thing

Same goal, different mechanism — check any of them against this one

Probiotics for Autoimmune Disease Support Gut health & immune modulation 10-100 billion CFU daily B 60% Magnesium Glycinate Superior absorption sleep & muscle support 200-600 mg A 90% Magnesium Citrate Balanced absorption & digestive support 300-600 mg A 35% Chloride Electrolyte & digestive support 2300mg A 95% Bone Broth Collagen Gut healing & collagen support 20-40g powder B 85% Psyllium Husk Digestive health & cholesterol support 5-15g A 95%

Every pair we checked

12 combinations scored by the engine

Saccharomyces boulardii + Caffeine No documented interaction either way No known interaction 70

Saccharomyces boulardii + Creatine Monohydrate No documented interaction either way No known interaction 70

Saccharomyces boulardii + Calcium Carbonate No documented interaction either way No known interaction 70

Saccharomyces boulardii + Whey Protein No documented interaction either way No known interaction 70

Saccharomyces boulardii + Lactase No documented interaction either way No known interaction 70

Saccharomyces boulardii + Bovine Collagen No documented interaction either way No known interaction 70

Saccharomyces boulardii + DHA No documented interaction either way No known interaction 70

Saccharomyces boulardii + Turmeric No documented interaction either way No known interaction 70

Saccharomyces boulardii + Fish Oil (EPA/DHA) No documented interaction either way No known interaction 70

Saccharomyces boulardii + Zinc Gluconate Enhanced immune function and gut barrier support Works better together 78

Saccharomyces boulardii + Vitamin D3 Synergistic immune enhancement and antioxidant protection Works better together 78

Saccharomyces boulardii + Prebiotic Fiber Complex Improved gut microbiome diversity and health Works better together 78

Dosage

With meals or during antibiotics

Daily250-500mg

Antibiotic protection250-500mg twice daily during and after treatment

C difficile prevention250-500mg twice daily during high-risk periods

Immune support250-500mg daily

Digestive maintenance250mg daily with meals

When to expect it

First Effects1-2 weeks for digestive protection and pathogen resistance

Peak Benefits2-8 weeks for maximum digestive and immune benefits

Deficiency DevelopmentBeneficial microorganisms depleted by antibiotics, infections, stress

Toxicity OnsetExtremely rare - safe for most individuals

How to measure it

$200-400

MarkerC. difficile toxins, immune markers, inflammatory markers

OptimalNegative C. difficile toxins, balanced immune function

Deficient belowPositive pathogen markers, compromised immune function

FrequencyMonitor during antibiotic treatment or high-risk periods

What people actually reported to the FDA

CAERS, 60 reports naming it as the suspect

Most reported effects

Fungaemia 26

Death 8

Fungal infection 6

Diarrhoea 5

Clostridium difficile infection 5

Named as the suspect 60 reports of 62 that mention it at all

Serious outcome 94% hospitalisation, emergency room or worse

Hospitalization32

Other Serious or Important Medical Event31

Other Serious Outcome23

Reports are voluntary and unverified — they record what someone experienced while taking something, not what the compound caused. Counts skew towards products people take a lot of, and a serious outcome is more likely to be reported than a mild one, so these are not rates. How we filter them →

What actually reaches you

The label counts the carrier, your body does not

Absorption Very high 80 of 100 · best absorbed form of this compound

Delivered daily 300 mg

Cost per 100 mg delivered $0.44 comparative — uses the absorption score, not a measured percentage

Works better with

3 documented

Zinc

Enhanced immune function and gut barrier support

Both support immune system and intestinal health · level B

Vitamin C

Synergistic immune enhancement and antioxidant protection

Both support immune function through complementary pathways · level B

Prebiotic Fiber

Improved gut microbiome diversity and health

Prebiotics support beneficial microorganisms including yeast · level B

What not to take with Saccharomyces boulardii

3 documented

Antifungal Medications

Antifungals eliminate S. boulardii and reduce effectiveness

Antifungal action kills beneficial yeast · high significance

Excessive Heat

High temperatures may reduce yeast viability

Heat damages yeast cell structure and function · moderate significance

Chronic Stress

Long-term stress may impair probiotic effectiveness

Stress hormones affect gut microbiome and immune function · moderate significance

Medication interactions

Discuss these with a pharmacist before combining

antibiotics Beneficial

S. boulardii is naturally resistant to antibiotics

What to do: Can be taken during antibiotic treatment

antifungal-medications Moderate

Antifungals significantly reduce S. boulardii effectiveness

What to do: Avoid concurrent use with systemic antifungals

Available forms

bioavailability compared

Saccharomyces boulardii (Freeze-dried yeast) 80

Saccharomyces boulardii (Freeze-dried yeast): Antibiotic resistance, Clinical validation, Pathogen protection, Immune support

Food sources

before you supplement

Lychee fruit (original source) Natural trace amounts · 60

Fermented foods (very limited) Minimal presence in most foods · 50

Functional foods with added S. boulardii Variable, typically 10^6-10^8 organisms · 70

S. boulardii probiotic supplements 250-500mg (5-10 billion organisms) per serving · 80

Too little

deficiency signs

Gut microbiome imbalance symptoms:
Antibiotic-associated diarrhea and digestive disruption
Increased risk of C. difficile and other infections
Compromised immune function and frequent illnesses
Poor digestive health and gut barrier dysfunction
Reduced resistance to gastrointestinal pathogens
Travelers' diarrhea and digestive issues

Too much

toxicity signs

Generally safe with minimal adverse effects:
Temporary digestive adjustment during initial supplementation
Very rare fungemia risk in severely immunocompromised patients
No documented serious adverse effects in healthy individuals
Safe for short to medium-term use

Who benefits most

antibiotic-users

Clinically proven to prevent antibiotic-associated diarrhea

250-500mg twice daily during and after antibiotic treatment

c-difficile-risk-patients

Reduces risk of C. difficile-associated diarrhea and recurrence

250-500mg twice daily during high-risk periods

immune-system-support

Strengthens immune function and reduces infection susceptibility

250-500mg daily

digestive-health-maintenance

Supports overall gut health and digestive function

250mg daily with meals

travelers-diarrhea-prevention

May help prevent travelers' diarrhea and digestive issues

250-500mg daily during travel

Where to buy it

compare forms first

Look for Saccharomyces boulardii at 250-500mg per serving. The form that matters here is Saccharomyces boulardii (Freeze-dried yeast).

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What else affects it

Beyond other supplements

Excessive heat

High temperatures may reduce yeast viability

Heat damages yeast cell structure and function

Chronic stress

Long-term stress may impair probiotic effectiveness

Stress hormones affect gut microbiome and immune function

How it works

Naturally resistant to antibiotics allowing survival during treatment
Produces compounds that inhibit C. difficile growth and toxin production
Stimulates secretory IgA production for mucosal immunity
Modulates immune cell activity and cytokine production
Competes with pathogenic organisms for nutrients and binding sites
Produces antifungal and antibacterial compounds protecting gut health

Key findings

what the evidence supports

Most clinically validated probiotic yeast for antibiotic-associated diarrhea
Proven effectiveness for C. difficile infection prevention
Strong evidence for immune system enhancement
Good safety profile with rare adverse effects in healthy individuals

Sources: NIH Examine.com · data reviewed 2026-08-02

Compiled by Denis, who maintains this database and holds no medical qualification — every figure here is sourced or derived, never asserted. How we calculate it →

Common questions

What are the benefits of Saccharomyces boulardii?

Documented effects: Prevention of antibiotic-associated diarrhea; Protection against C. difficile infections; Enhanced immune system function; Improved digestive health and gut barrier. Clinically proven to prevent diarrhea during and after antibiotic treatment

How much Saccharomyces boulardii should you take per day?

The common daily range is 250-500mg. By goal — antibiotic protection: 250-500mg twice daily during and after treatment; c difficile prevention: 250-500mg twice daily during high-risk periods; immune support: 250-500mg daily; digestive maintenance: 250mg daily with meals.

When is the best time to take Saccharomyces boulardii?

With meals or during antibiotics. First effects are typically reported within 1-2 weeks for digestive protection and pathogen resistance.

What are the side effects of Saccharomyces boulardii?

At excessive doses: Generally safe with minimal adverse effects:, Temporary digestive adjustment during initial supplementation, Very rare fungemia risk in severely immunocompromised patients, No documented serious adverse effects in healthy individuals, Safe for short to medium-term use. Safety rating at normal doses is 9 out of 10.

What should you not take with Saccharomyces boulardii?

Separate it from Antifungal Medications, Excessive Heat, Chronic Stress by two to four hours. Antifungals eliminate S. boulardii and reduce effectiveness

Does Saccharomyces boulardii interact with medications?

Documented interactions with antibiotics, antifungal-medications. Discuss these with a pharmacist before combining.

How do you know if you need Saccharomyces boulardii?

The marker is C. difficile toxins, immune markers, inflammatory markers, optimal range Negative C. difficile toxins, balanced immune function. Common deficiency signs: Gut microbiome imbalance symptoms:, Antibiotic-associated diarrhea and digestive disruption, Increased risk of C. difficile and other infections, Compromised immune function and frequent illnesses.

Taken for

74 Digestion

Lactase · Lactobacillus acidophilus · Protease