Probiotics and medications.
Probiotics is in the Distil supplement database, evidence Grade A. The page below lists every medication we have explicitly assessed it against.
Probiotics support gut microbiome diversity, immune signalling and the gut-brain axis, but the headline rule is that the evidence is strain-specific. A product labelled only "multi-strain" without named strains tells you little. The strongest data sit with particular strains for particular jobs: Lactobacillus plantarum 299v for IBS, Saccharomyces boulardii for antibiotic-associated diarrhoea, and Lactobacillus rhamnosus GG for diarrhoea prevention, all Grade A in their niche, while general wellness claims are Grade B. Hungin 2013 and later meta-analyses back the IBS use, and Dinan 2013 covers the psychobiotic mood angle. Doses run from 10 to 50 billion CFU across at least five named species. The interactions are simple but important. Keep probiotics at least two hours apart from antibiotics, since taken together the antibiotic kills the live organisms. Prebiotic fibre such as inulin, FOS or psyllium feeds and sustains the colonisation. Some bloating on starting is normal and usually settles within a week or two.
Below are the 16 documented pairs we have explicitly assessed for Probiotics: 6 amber and 10 green. The pairs cluster around 2 mechanisms: Immunosuppression caution and Probiotic timing with antibiotics. Every call is cited to either a clinical reference (PMID) or the British National Formulary. Anything not listed here is either still to be assessed or beyond our database scope. The checker beneath surfaces assessments by medication, and the missing-item form at the bottom of the page routes any uncatalogued medication into our next curation pass.
Documented interactions
Last reviewed 15 June 2026. Each interaction below lists the evidence its assessment drew on: some rest on studies of the exact pair, others on mechanism evidence, where a citation may support one part of the reasoning rather than the exact combination. The evidence line on each entry says which.
Immunosuppression caution
Amber Does interact with Azathioprine?
If you take azathioprine, it is sensible to check with your specialist before starting a probiotic: azathioprine dampens the immune system, often for an autoimmune condition or after a transplant, and in people whose defences are significantly weakened there have been rare cases of the probiotic organism getting into the bloodstream and causing an infection. Avoid any probiotic if you are seriously unwell in hospital or have a central line or drip. Probiotics are live bacteria or yeast, and the evidence that they are safe for most people comes from studies of people who were not significantly immunosuppressed, so on azathioprine let your specialist's advice decide.
Evidence: Supported by human study data.
Amber Does interact with Ciclosporin?
If you take ciclosporin, check with your specialist team before starting a probiotic: ciclosporin strongly dampens the immune system, usually after a transplant or for a serious autoimmune condition, and in people whose defences are this weakened there have been rare cases of the probiotic organism getting into the bloodstream and causing an infection. Avoid any probiotic if you are seriously unwell in hospital or have a central line or drip. Probiotics are live bacteria or yeast, and the evidence that they are safe for most people comes from studies of people who were not significantly immunosuppressed, so on ciclosporin let your specialist team's advice decide.
Evidence: Supported by human study data.
Amber Does interact with Everolimus?
If you take everolimus, check with your specialist team before starting a probiotic: everolimus strongly dampens the immune system, used after a transplant or in some cancers, and in people whose defences are this weakened there have been rare cases of the probiotic organism getting into the bloodstream and causing an infection. Avoid any probiotic if you are seriously unwell in hospital or have a central line or drip. Probiotics are live bacteria or yeast, and the evidence that they are safe for most people comes from studies of people who were not significantly immunosuppressed, so on everolimus let your specialist team's advice decide.
Evidence: Supported by human study data.
Amber Does interact with Methotrexate?
If you take methotrexate, it is sensible to check with your specialist before starting a probiotic: methotrexate dampens the immune system, and in people whose defences are significantly weakened there have been rare cases of the probiotic organism getting into the bloodstream and causing an infection. At the usual low weekly doses for arthritis or psoriasis this risk is small. Avoid any probiotic if you are seriously unwell in hospital or have a central line or drip. Probiotics are live bacteria or yeast, and the evidence that they are safe for most people comes from studies of people who were not significantly immunosuppressed, so on methotrexate let your specialist's advice decide.
Evidence: Supported by human study data.
Amber Does interact with Sirolimus?
If you take sirolimus, check with your specialist team before starting a probiotic: sirolimus strongly dampens the immune system, usually after a transplant, and in people whose defences are this weakened there have been rare cases of the probiotic organism getting into the bloodstream and causing an infection. Avoid any probiotic if you are seriously unwell in hospital or have a central line or drip. Probiotics are live bacteria or yeast, and the evidence that they are safe for most people comes from studies of people who were not significantly immunosuppressed, so on sirolimus let your specialist team's advice decide.
Evidence: Supported by human study data.
Amber Does interact with Tacrolimus?
If you take tacrolimus, check with your specialist team before starting a probiotic: tacrolimus strongly dampens the immune system, usually after a transplant or for a serious autoimmune condition, and in people whose defences are this weakened there have been rare cases of the probiotic organism getting into the bloodstream and causing an infection. Avoid any probiotic if you are seriously unwell in hospital or have a central line or drip. Probiotics are live bacteria or yeast, and the evidence that they are safe for most people comes from studies of people who were not significantly immunosuppressed, so on tacrolimus let your specialist team's advice decide.
Evidence: Supported by human study data.
Probiotic timing with antibiotics
Green Does interact with Amoxicillin?
Probiotics and amoxicillin are fine to use together, and probiotics may lower the chance of antibiotic-related diarrhoea. If you take a bacterial probiotic (most Lactobacillus or Bifidobacterium products), space it about two hours away from your amoxicillin dose so the antibiotic does not reduce the live bacteria. Saccharomyces boulardii is a yeast rather than a bacterium, so the antibiotic does not affect it and it can be taken at the same time. The main exception is if your immune system is seriously weakened or you are critically ill in hospital, when probiotics, particularly Saccharomyces boulardii, should be checked with your doctor first.
Evidence: Supported by human study data.
Green Does interact with Ciprofloxacin?
Probiotics and ciprofloxacin are fine to use together, and probiotics may lower the chance of antibiotic-related diarrhoea. If you take a bacterial probiotic (most Lactobacillus or Bifidobacterium products), space it about two hours away from your ciprofloxacin dose so the antibiotic does not reduce the live bacteria. Saccharomyces boulardii is a yeast rather than a bacterium, so the antibiotic does not affect it and it can be taken at the same time. The main exception is if your immune system is seriously weakened or you are critically ill in hospital, when probiotics, particularly Saccharomyces boulardii, should be checked with your doctor first.
Evidence: Supported by human study data.
Green Does interact with Clarithromycin?
Probiotics and clarithromycin are fine to use together, and probiotics may lower the chance of antibiotic-related diarrhoea. If you take a bacterial probiotic (most Lactobacillus or Bifidobacterium products), space it about two hours away from your clarithromycin dose so the antibiotic does not reduce the live bacteria. Saccharomyces boulardii is a yeast rather than a bacterium, so the antibiotic does not affect it and it can be taken at the same time. The main exception is if your immune system is seriously weakened or you are critically ill in hospital, when probiotics, particularly Saccharomyces boulardii, should be checked with your doctor first.
Evidence: Supported by human study data.
Green Does interact with Co-trimoxazole?
Probiotics and co-trimoxazole are fine to use together, and probiotics may lower the chance of antibiotic-related diarrhoea. If you take a bacterial probiotic (most Lactobacillus or Bifidobacterium products), space it about two hours away from your co-trimoxazole dose so the antibiotic does not reduce the live bacteria. Saccharomyces boulardii is a yeast rather than a bacterium, so the antibiotic does not affect it and it can be taken at the same time. The main exception is if your immune system is seriously weakened or you are critically ill in hospital, when probiotics, particularly Saccharomyces boulardii, should be checked with your doctor first.
Evidence: Supported by human study data.
Green Does interact with Doxycycline?
Probiotics and doxycycline are fine to use together, and probiotics may lower the chance of antibiotic-related diarrhoea. If you take a bacterial probiotic (most Lactobacillus or Bifidobacterium products), space it about two hours away from your doxycycline dose so the antibiotic does not reduce the live bacteria. Saccharomyces boulardii is a yeast rather than a bacterium, so the antibiotic does not affect it and it can be taken at the same time. The main exception is if your immune system is seriously weakened or you are critically ill in hospital, when probiotics, particularly Saccharomyces boulardii, should be checked with your doctor first.
Evidence: Supported by human study data.
Green Does interact with Erythromycin?
Probiotics and erythromycin are fine to use together, and probiotics may lower the chance of antibiotic-related diarrhoea. If you take a bacterial probiotic (most Lactobacillus or Bifidobacterium products), space it about two hours away from your erythromycin dose so the antibiotic does not reduce the live bacteria. Saccharomyces boulardii is a yeast rather than a bacterium, so the antibiotic does not affect it and it can be taken at the same time. The main exception is if your immune system is seriously weakened or you are critically ill in hospital, when probiotics, particularly Saccharomyces boulardii, should be checked with your doctor first.
Evidence: Supported by human study data.
Green Does interact with Metronidazole?
Probiotics and metronidazole are fine to use together, and probiotics may lower the chance of antibiotic-related diarrhoea. If you take a bacterial probiotic (most Lactobacillus or Bifidobacterium products), space it about two hours away from your metronidazole dose so the antibiotic does not reduce the live bacteria. Saccharomyces boulardii is a yeast rather than a bacterium, so the antibiotic does not affect it and it can be taken at the same time. The main exception is if your immune system is seriously weakened or you are critically ill in hospital, when probiotics, particularly Saccharomyces boulardii, should be checked with your doctor first.
Evidence: Supported by human study data.
Green Does interact with Minocycline?
Probiotics and minocycline are fine to use together, and probiotics may lower the chance of antibiotic-related diarrhoea. If you take a bacterial probiotic (most Lactobacillus or Bifidobacterium products), space it about two hours away from your minocycline dose so the antibiotic does not reduce the live bacteria. Saccharomyces boulardii is a yeast rather than a bacterium, so the antibiotic does not affect it and it can be taken at the same time. The main exception is if your immune system is seriously weakened or you are critically ill in hospital, when probiotics should be checked with your doctor first.
Evidence: Supported by human study data.
Green Does interact with Nitrofurantoin?
Probiotics and nitrofurantoin are fine to use together, and probiotics may lower the chance of antibiotic-related diarrhoea. If you take a bacterial probiotic (most Lactobacillus or Bifidobacterium products), space it about two hours away from your nitrofurantoin dose so the antibiotic does not reduce the live bacteria. Saccharomyces boulardii is a yeast rather than a bacterium, so the antibiotic does not affect it and it can be taken at the same time. The main exception is if your immune system is seriously weakened or you are critically ill in hospital, when probiotics, particularly Saccharomyces boulardii, should be checked with your doctor first.
Evidence: Supported by human study data.
Green Does interact with Trimethoprim?
Probiotics and trimethoprim are fine to use together, and probiotics may lower the chance of antibiotic-related diarrhoea. If you take a bacterial probiotic (most Lactobacillus or Bifidobacterium products), space it about two hours away from your trimethoprim dose so the antibiotic does not reduce the live bacteria. Saccharomyces boulardii is a yeast rather than a bacterium, so the antibiotic does not affect it and it can be taken at the same time. The main exception is if your immune system is seriously weakened or you are critically ill in hospital, when probiotics, particularly Saccharomyces boulardii, should be checked with your doctor first.
Evidence: Supported by human study data.
What this list does not say. Pairs not flagged here are not implicitly safe. They are either not yet in our database, or fall outside our inclusion scope. Use the checker below to surface any medication, and submit a missing item if you take something we have not catalogued.
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How we grade severity, choose what's in scope, and what we exclude.
Every call on this page is reasoned. We publish the full rubric for severity tiers, the medication inclusion logic, the evidence grades we accept, and what we deliberately leave out. About three thousand words. Worth reading once if you use this tool more than occasionally.
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The interaction check is one section of the full report. You also get the reasoning behind each recommendation and the evidence references used.
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