Diarrhoea: Can probiotics help?

Probiotics - bacterial cultures that are particularly found in some dairy products – can make diarrhoea stop noticeably sooner.

Diarrhoea is often caused by an infection. In industrialised countries, life-threatening cases of diarrhoea have become uncommon. For mild diarrhoea, simply drinking plenty of fluids so you do not dehydrate and waiting for it to run its course is often enough. However, small children and older people can quickly become so dehydrated that it becomes dangerous and special treatment is needed.

For mild diarrhoea, some experts advise people to eat foods containing a certain kind of bacteria. These are believed to reach the bowel and protect against the germs that cause diarrhoea there. These bacteria are often called “probiotics”. Probiotics are a familiar ingredient in some dairy products, like yoghurt and yoghurt-type drinks.

To find out whether or not probiotics really can help with diarrhoea, researchers from the Cochrane Collaboration, an international network of researchers, systematically analysed trials. The topic has been well studied: They found 23 trials, in which over 2,000 people tested probiotics, mainly in yoghurt drinks, milk or baby formula. Most of the people were children who had had diarrhoea for less than two weeks.

Probiotics proved to be a useful additional option for people with diarrhoea. In the trials where the length of diarrhoea episodes was recorded, probiotics shortened the illness by up to 30 hours. In some of the other trials, the researchers had counted how many of the people had no more diarrhoea after a few days. Out of 100 people who were not taking probiotics, about 40 were free of diarrhoea after three days (40%), compared to 60 out of 100 people who were taking probiotics (60%). The studies did not apparently examine whether or not the probiotics had adverse effects, but that was often not the focus of the research. There have been other studies, though, which found that people who had weak immune systems developed infections after using probiotics.

An important question remains: a wide variety of products are labelled 'probiotic', including powders, tablets and special dietary drinks. Not all of them contain living probiotics. It is not clear whether they are all equally effective.

In March 2009, to update this article, we did a search for the latest studies on the efficacy of probiotics in the treatment of infectious diarrhoea. We found reviews of trials which only included babies and children up to the age of 12. The outcomes of these reviews are in line with previous conclusions. The Cochrane researchers are currently updating their systematic review. As soon as their results become available, we will write about them here.


Author: German Institute for Quality and Efficiency in Health Care (IQWiG)

© IQWiG (Institute for Quality and Efficiency in Health Care)