Lactobacillus is a type of rod-shaped bacteria that normally inhabits our oral, digestive and genital cavities. It is also present in some fermented foods like yogurts or dietary supplements. Its name comes from its ability to convert lactose and other sugars into lactic acid. Due to their effectiveness, lactobacilli are normally used for treating and preventing diarrhoea, including some infectious types such as rotavirus diarrhoea in children or traveller’s diarrhoea.