Diarrhoea: Can probiotics help?

Probiotics, which are cultures also found in some milk products like yoghurts, can make a noticeable difference to diarrhoea.

Diarrhoea is often caused by bacteria (germs). In industrialised countries, life-threatening cases of diarrhoea have become uncommon. For mild diarrhoea, it is often enough to drink plenty of fluids so you do not dehydrate, and wait for the diarrhoea to run its course. However in small children and older people, dehydration can happen quickly, and it can quickly become dangerous. That means that special care, and often treatment, will be necessary.

For mild diarrhoea, though, another common piece of advice is to use dietary supplements or foods containing probiotics. These are believed to reach the bowel and protect against bacteria there. 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 systematically analysed trials. The topic has been well studied. The researchers found 23 trials, in which over 2,000 people tested probiotics, as dietary supplements or 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. It does not replace other care and treatment for diarrhoea, though, such as guarding against dehydration. In the trials where the length of the case of diarrhoea was counted, probiotics shortened the illness by about 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%). But with probiotics, the number of people free of diarrhoea was 60 out of 100 (60%).

The studies did not apparently examine whether or not there were adverse effects from using probiotics. There have been other studies, though, where people who have weaknesses in their immune system 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. Not all yoghurts contain the particular probiotics tested here, which were lactobacilli or particular yeasts. It is still not clear, exactly which of these products are effective.

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