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Probiotics

Also known as: Lactobacillus, Bifidobacterium, Saccharomyces boulardii

Live microorganisms. Effects are strain-specific — results for one product don't apply to all.

Common forms: Capsules · Powders · Fermented foods

Draft summary, not yet reviewed by a qualified health professional · Last updated 2026-11-03

Talk to a healthcare professional first

This information is for education only and is not medical advice, diagnosis, or treatment. Supplements can interact with medications and health conditions. Check with your doctor or pharmacist before starting anything, especially if you take medication, are pregnant or breastfeeding, or have a health condition. These statements have not been evaluated by the FDA; supplements are not intended to diagnose, treat, cure, or prevent any disease.

What the evidence says

Gut comfort

BModerate evidence

Meta-analyses found probiotics taken during antibiotic treatment reduced the risk of antibiotic-associated diarrhea. Evidence for IBS symptoms is weaker and depends on the strain.

Dose used in studies
Strain-specific; commonly 5–40 billion CFU/day during and 1 week after antibiotics
Time to effect
During the antibiotic course
Most relevant for
People taking antibiotics; specific strains for IBS
Studies (3)

Safety

Common side effects

  • Gas
  • Bloating in the first days

Avoid or ask your doctor first if

  • You are immunocompromised, critically ill, or have a central line (risk of infection)

Pregnancy & breastfeeding

Not enough safety data — avoid unless your provider recommends it.

Medication interactions

  • majorImmunosuppressants: Risk of serious infection from the probiotic organisms.

This list covers common medication classes only and is not exhaustive.

Buying tips

Look for third-party testing seals (USP Verified, NSF Certified, or Informed Choice) and match the form and dose used in studies.

Where to buy (affiliate)

Further reading