Probiotics decrease antibiotic-associated diarrhea

Probiotics decrease antibiotic-associated diarrhea – POEMs

* Clinical question

Can probiotics decrease the likelihood of antibiotic-associated diarrhea?


Probiotics are living microorganisms given with the intent of colonizing the intestine to prevent or alleviate disease. The most common are Lactobacillus spp and Saccharomyces spp. The researchers conducting this meta-analysis did a comprehensive search of the published and unpublished literature on the topic, finding 41 studies. However, only seven were randomized, placebo-controlled, and provided at least two weeks of data (n = 881). The researchers assessed the quality of the studies but didn’t report this information, so we don’t know about blinding, concealed allocation, or method of analysis. Two of the studies were conducted in infants and children. Four studies evaluated Lactobacillus spp and three studies evaluated Saccharomyces boulardi. A variety of antibiotics were used in the studies, and the result they evaluated was the occurrence (yes/no) of diarrhea during the course of treatment. Two additional studies have been published since the completion of this meta-analysis, and the good people at Ban dolier have extended the meta-analysis and provided more useful data (see: The relative risk of experiencing diarrhea during antibiotic therapy was decreased 40% with the use of probiotics (relative risk = 0.6; 95% CI, 0.4-0.7). In other words, for every 10 patients given a probiotic/antibiotic combination (sounds counterintuitive), one patient will be prevented from experiencing diarrhea (NNT = 10, 95% CI, 7.1 – 17). In the US, where there is no regulation of these products, the usual caveats apply–we cannot be sure that the products listing these ingredients actually contain them, and in what quantities.

Bottom line

“Probiotics” containing species of the bacteria Lactobacillus or Saccharomyces will decrease the likelihood of diarrhea due to antibiotic administration in children or adults (absolute risk reduction, 13% to 23%; NNT = 10). Tell patients to look for these products in the “diarrhea section.” A typical dose is 5 to 10 billion viable organisms administered three to four times a day. Separate the taking of the bugs from the antibiotics by a couple hours.


Cremonini F, Di Caro S, Nista EC, et al. Meta-analysis: the effect of probiotic administration on antibiotic-associated diarrhoea. Aliment Pharmacol Ther. 2002;16:1461-1467.

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