When do probiotics help, and can they treat IBS or yeast infections?
Probiotic effects depend on the strain, dose and condition; findings for one product cannot be generalized to others. Selected formulations may help in particular situations, but evidence for IBS treatment is uncertain. Evidence does not support replacing prescribed vaginal yeast infection treatment with probiotics.
Details
The strain matters more than marketing
A familiar bacterial name or a large organism count does not establish benefit. Ask which strain was studied for the intended problem, for how long, and how improvement will be judged. Recommendations vary, and no single supplement suits all digestive symptoms.
Limits of use
Some formulations may reduce antibiotic-associated diarrhoea, but are not automatically necessary with every prescription. AGA guidance limits use for IBS to clinical trials because of an evidence gap. CDC guidance notes a lack of substantial evidence for treating vaginal candidiasis with probiotics.
Who needs extra caution?
Severe immune compromise, critical illness or prematurity requires specialist advice because rare infections can occur. Probiotics do not replace oral rehydration or necessary assessment for bloody diarrhoea or dehydration.
Related reading: Can yoghurt support gut bacteria, and how should I choose a product?.