Study researchers reviewed 63 randomized controlled trials (RCTs) that totaled nearly 12,000 patients and their use of probiotics (Lactobacillus, Bifidobacterium, Saccharomyces, Streptococcus, Enterococcus, and/or Bacillus) for the prevention or treatment of antibiotic-associated diarrhea (AAD) as it related to the treatment of a spectrum of conditions spanning from ear infections to sepsis. They found 42% were less likely to get diarrhea from their antibiotic drugs if they were also taking a probiotic.
In an article published by Reuters, one of the researchers - Sydne Newberry from the RAND Corporation in Santa Monica, CA – said, "Antibiotics in doing their work actually kill off a lot of the normal flora that are supposed to exist in our gut, so things kind of go haywire. More than likely, what they do is they start to actually restore the normal bacteria in the gut, in the intestines."
In terms of dosage information, the researcher conceded that most of the studies were small and didn't include a report on the side effects associated with probiotics. They did, however, conclude that the supplements seemed safe.