Taking antibiotics? Probiotics can cut your risk of diarrhoea

Key message: moderate quality evidence suggests that probiotics are both safe and effective for preventing Clostridium difficile-associated diarrhoea.

It’s no surprise that a new Cochrane review made headline news on the BBC’s health pages last week and was featured in many other health news reports too, as its focus was the use of probiotics to prevent Clostridium difficile-associated diarrhoea (CDAD) in people taking antibiotics. These medicines can upset the normal healthy balance of organisms in the gut and open the door to infection, often by C.difficile bacteria. It’s a very common side-effect and one you may well have experienced. Perhaps you’ve also bought probiotic supplements from your health food shop or supermarket. These are products containing live micro-organisms which, when taken in adequate amounts, offer a health benefit. They’re not to be confused with prebiotics, which are the food nutrients which feed the “good bacteria” in our bodies.

Infection with C.difficile results in considerable costs in treatment and for the person infected the consequences range from no symptoms to diarrhoea, colitis or even death. Probiotics are BIG business and there will be much interest in this review from those involved in producing and selling probiotic products as well as those funding, prescribing and taking antibiotics.

The review, from the Cochrane Inflammatory Bowel Disease and Functional Bowel Disorders Group, looked at evidence from randomized controlled trials (RCTs) on the effectiveness and safety of probiotics for preventing CDAD in adults and children. They were able to include 23 RCTs with 4213 people taking antibiotics for any reason, with data which could be combined in a meta-analysis.

What did they find?

  • Probiotics reduced the risk of CDAD, by 64%. 2% of the probiotic group got CDAD compared with 5.5% of the control group. This suggests that 29 people need to be treated to prevent one case of CDAD
  • Probiotics did not reduce the incidence of C.difficile infection
  • Probiotics reduced the risk of side effects by 20%. In both groups side effects included stomach cramps, feeling sick and taste disturbance
  • Limited data from three RCTs found no difference in length of time in hospital

How good is the evidence?

Overall, the evidence was judged to be of moderate quality. The low risk of bias studies suggested a stronger protective effect of probiotics than the high risk of bias studies. Looking at the data in various ways, to explore the possible effect of missing data for example, did not weaken the results and the reviewers judge that the evidence warrants modest confidence in the findings that taking probiotics significantly reduces your risk of CDAD but doesn’t lower the risk of infection. There was a lot of variation in descriptions of side effects; again the reviewers judged that overall the data on side effects is of moderate quality.

So what does this change?

In a press release, lead researcher Bradley Johnston of The Hospital for Sick Children Research Institute in Toronto, Canada said that giving probiotics to people on antibiotics “…could have an immediate impact on patient outcomes, especially in outbreak settings.” He cautioned “we still need to establish the probiotic strains and doses that provide the best results, and determine the safety of probiotics in immunocompromised patients.”

Further, the review suggests that probiotics prevent symptoms of infection or limit the infection, rather than preventing the infection itself; and this is something that future research could explore, possibly throwing some light on how probiotics prevent CDAD too.


Goldenberg JZ, Ma SSY, Saxton JD, Martzen MR, Vandvik PO, Thorlund K, Guyatt GH, Johnston BC. Probiotics for the prevention of Clostridium difficile-associated diarrhea in adults and children. Cochrane Database of Systematic Reviews 2013, Issue 5. Art. No.: CD006095. DOI: 10.1002/14651858.CD006095.pub3.

Cochrane summary of this review http://summaries.cochrane.org/CD006095/the-use-of-probiotics-to-prevent-c.-difficile-diarrhea-associated-with-antibiotic-use

BBC News Health Probiotics ‘may help when on antibiotics’ study says. 31st May 2013 http://www.bbc.co.uk/news/health-22717273#?utm_source=twitterfeed&utm_medium=twitter

Taking antibiotics? Probiotics can cut your risk of diarrhoea by Sarah Chapman

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