Who benefits most from taking probiotics with antibiotics?
Children are a clear group that can benefit. In a randomized, quadruple-blind, placebo-controlled trial of 350 children aged 3 months to 18 years, taking a multispecies probiotic (containing eight strains) during and for 7 days after antibiotic treatment reduced the overall risk of diarrhea by 35% (relative risk 0.65) compared to placebo [1]. While the probiotic did not reduce the most strictly defined antibiotic-associated diarrhea (AAD), it did lower the chance of any diarrhea, which is the main practical concern for parents and clinicians.
Men with male accessory gland infections (MAGI) also benefit significantly. In a study of 104 infertile men with confirmed bacterial infections, those who received a specific probiotic combination (Enterococcus faecium and Saccharomyces boulardii during antibiotics, followed by Lactobacilli) had a 76% infection eradication rate, compared to only 50% in those who received antibiotics alone [3]. This means adding probiotics nearly halved the rate of persistent infection.
Healthy dogs, as a model for humans, also show benefit. In a study of 14 dogs given a single antibiotic injection, those receiving a daily probiotic complex for two weeks had significantly higher gut microbial diversity and lower levels of a marker of antibiotic-induced dysbiosis (Clostridioides) compared to dogs that did not get probiotics [2]. This suggests probiotics help restore a healthy gut microbiome after antibiotic disruption.
Does the evidence show probiotics reliably prevent antibiotic-associated diarrhea?
The evidence is mixed and depends on how you define diarrhea. The largest and most rigorous study here, a 2022 trial of 350 children, found that a multispecies probiotic did not reduce the risk of AAD when defined strictly as 3 or more loose stools per day with a specific cause (relative risk 0.81, not statistically significant) [1]. However, when they looked at diarrhea from any cause—which is more relevant to daily life—the probiotic group had a 35% lower risk [1]. This highlights that the definition of AAD strongly influences trial results.
Other research supports probiotics for AAD. A 2022 review notes that many randomized trials and meta-analyses, especially those using Lactobacillus and Saccharomyces strains, have shown benefits in preventing AAD [4]. In a mouse model of ampicillin-induced AAD, a complex probiotic mixture significantly reduced fecal water content, loose stool grade, and intestinal permeability, while also increasing beneficial gut bacteria like Lactobacillus and reducing harmful ones like Klebsiella [5]. These animal results align with the human data, suggesting probiotics can help, but the effect may be modest and strain-specific.
What are the limitations and caveats?
Not all probiotics work the same way, and not all patients benefit equally. The 2022 children's trial used a specific eight-strain probiotic and found no effect on the strictest AAD definition, while the MAGI study used a different combination (Enterococcus faecium and Saccharomyces boulardii) and found a clear benefit for infection clearance [1][3]. This means the specific probiotic strain, dose, and patient condition matter greatly.
The evidence is also limited by study design and scope. The dog study had only 14 animals, and the MAGI study was not blinded or randomized [2][3]. The mouse study, while showing benefits, is an animal model and may not directly translate to humans [5]. Additionally, a 2023 study on peritonitis patients suggests probiotics can be effective for abdominal cavity rehabilitation, but this is a very specific surgical context [6]. Overall, while probiotics appear safe and inexpensive, their benefit is not guaranteed for everyone, and more research is needed to identify which patients and which probiotic formulations work best.
About These Sources
This answer is built on 6 peer-reviewed studies — published from 2022 to 2025, 1 from 2024 or later, 3 in Q1 journals, collectively cited 165 times — selected as the most relevant from 6 studies that passed quality screening, drawn from 56 papers retrieved from a database of over 500 million.
Sources used in this answer
Multispecies Probiotic for the Prevention of Antibiotic-Associated Diarrhea in Children
In a randomized, quadruple-blind, placebo-controlled trial of 350 children, a multispecies probiotic did not reduce strictly defined antibiotic-associated diarrhea (AAD) but did reduce the overall risk of diarrhea from any cause by 35% (relative risk 0.65) during and for 7 days after antibiotics.
Beneficial effects of probiotics on dysbiosis of gut microbiota induced by antibiotic treatment in healthy dogs
In a study of 14 healthy dogs given a single antibiotic injection, those receiving a daily probiotic complex for two weeks had significantly higher gut microbial diversity and lower levels of the dysbiosis marker Clostridioides compared to dogs without probiotics.
Association of Probiotic Treatment With Antibiotics in Male Accessory Gland Infections
In 104 infertile men with male accessory gland infections, adding a specific probiotic combination (Enterococcus faecium and Saccharomyces boulardii) to antibiotics raised the infection eradication rate from 50% (antibiotics alone) to 76% (antibiotics plus probiotics).
Probiotics for the Prevention of Antibiotic-Associated Diarrhea
A 2022 review states that antibiotic-associated diarrhea affects up to 30% of patients, and many randomized trials and meta-analyses, particularly with Lactobacillus and Saccharomyces strains, show probiotics are a safe and inexpensive preventive option for AAD.
Complex probiotics alleviate ampicillin-induced antibiotic-associated diarrhea in mice
In a mouse model of ampicillin-induced AAD, a complex probiotic mixture significantly reduced fecal water content, loose stool grade, and intestinal permeability, while increasing beneficial gut bacteria like Lactobacillus and decreasing harmful ones like Klebsiella.
ANTIBIOTIC RESISTANCE, RATIONAL ANTIBIOTIC THERAPY AND PROBIOTICS IN THE COMPLEX TREATMENT OF PERITONITIS
A 2023 study on 360 peritonitis patients found that probiotic solutions are effective for abdominal cavity rehabilitation, but this is a specific surgical context and not directly about routine antibiotic use.