Selected strains of probiotics, including L. reuteri ATCC 55730, have been shown in several studies to reduce the duration and the severity of diarrhoea in children with acute gastroenteritis and the effect is greater if the probiotics are given within 60 hours from the onset of symptoms. Lactobacillus reuteri (L. reuteri) has been shown to reduce the duration and severity of acute gastroenteritis in children aged 6-36 months. In these studies L. reuteri was reported to have clinical effect on diarrhoea of both bacterial and viral (rotavirus) origin. Furthermore, L. reuteri strain DSM 17938 has recently been shown to reduce the duration of watery diarrhoea by 1.2 days among 6-36 mo old Italian children with acute gastroenteritis treated in hospital.