Rehydration fluids are the usual standard treatment for diarrhoea, but these do not reduce length of illness.
A Cochrane review found probiotics given in addition to these fluids can cut duration of diarrhoea and the chance of it lasting more than four days.
Last month, the European Food Safety Authority said probiotic drinks could not be shown to improve digestion or boost the immune system as the health claims made by such products were too general.
But a previous Cochrane review said probiotics may help patients by either eliminating or out-competing the bacteria, viruses or parasites responsible.
- Cochrane Database of Systematic Reviews 2010