Probiotics are live bacteria or yeasts. Effects depend on the strain and the reason for taking them; amounts are given in billions of CFU (colony-forming units).
Calculator Official intake Study doses Best form Safety Sources
This is not an essential nutrient, so there is no official daily intake. Only study doses are shown.
These are doses tested in research, not personal advice. Some exceed the upper limit because they were short courses or given under medical care.
No single dose
A Cochrane review of 39 studies (9,955 people) found probiotics during antibiotics cut C. difficile diarrhoea by about 60%, mainly in people at higher risk (over 5%). In children, diarrhoea from antibiotics fell from 19% to 8% (33 studies).
No best form
Why: Results come from specific strains, such as Lactobacillus rhamnosus GG and Saccharomyces boulardii; check that your product names its strains.
Yoghurt, kefir, sauerkraut and other fermented foods with live cultures.
Take them a few hours apart from antibiotic doses.
People who are very ill or have a weak immune system should ask a doctor first.
Pregnant, breastfeeding, on medication, or managing a health condition? Check with a doctor or pharmacist before starting a supplement.
Values checked: November 12, 2026.