An Over-the-Counter Evidence-Based Approach to Reducing the Risk of Antibiotic-Associated Diarrhea

Antibiotic-Associated Diarrhea: A Common Concern for Both Adults and Children

The impact of antibiotics on the gut microbiome is well documented, with lasting effects that can persist for months, leading to dysbiosis and the overgrowth of pathogenic bacteria. This often manifests in people as watery stools and diarrhea, commonly referred to as antibiotic-associated diarrhea (AAD). While nearly all antibiotics can contribute to AAD, the risk is higher with those that target anaerobes, such as aminopenicillins, combinations of aminopenicillins with clavulanate, cephalosporins, and clindamycin¹. Importantly, AAD may occur during antibiotic therapy or up to eight weeks following cessation^1,2, necessitating ongoing monitoring of patients during and beyond their treatment course.

AAD can affect both adults’ and children’s health and wellbeing^1,2,3. This issue typically occurs in between 5% and 35% of people taking antibiotics and varies depending upon the specific type of antibiotic, combinations of antibiotics and length of antibiotic course; the health of the person; and exposure to pathogens³. Among children receiving broad-spectrum antibiotics specifically, the incidence of diarrhea can range from 11% to 40%¹. Severe manifestations, such as colitis or pseudomembranous colitis, characterized by abdominal pain, fever, and bloody diarrhea, may occur in some cases⁴.

Pharmacists are uniquely positioned to reduce the risk of dysbiosis and AAD by recommending evidence-based probiotic supplementation, a clinically supported approach shown to lower both the incidence and severity of AAD in numerous studies⁵.

Among the most extensively studied probiotics for AAD prevention is Saccharomyces boulardii CNCM I-745^®, a yeast-based strain that has demonstrated robust efficacy and offers a distinct advantage over bacteria-based probiotics⁶.

Saccharomyces boulardii CNCM I-745: The Clinically Validated Yeast-Based Probiotic Strain for AAD

Saccharomyces boulardii CNCM I-745 (S. boulardii) has been extensively studied in clinical settings, with more than 130 trials conducted over 63 years supporting its role in promoting gastrointestinal health and maintaining digestive regularity⁷. Its unique properties, including antibiotic resistance and the ability to withstand the acidic environment of the stomach, distinguish it from other bacteria-based probiotics^7,8 and allow pharmacists to feel confident in their recommendation to take this probiotic strain at the same time with antibiotic regimens⁷.

Clinical studies consistently demonstrate the strain’s ability to significantly reduce the duration of diarrhea, particularly when administered within 72 hours of symptom onset⁹. One of the largest prospective, controlled, single-blind, multicenter clinical trials, conducted by Dinleyici, et al.⁹, investigated the effect of S. boulardii CNCM I-745 on the duration of diarrhea in hospitalized, emergency care, or ambulatory children with acute diarrhea. The trial included 363 children under 5 years old with acute watery diarrhea lasting 12 to 72 hours.

The study found that the number of hospitalized children taking S. boulardii CNCM I-745 and with diarrhea after 5 days was significantly reduced by 75% compared to the control group (10.1% vs. 36.8%; RR: 0.25; CI: 0.14-0.45), and the outpatient cohort saw a significant 95% reduction in diarrhea incidence after 72 hours compared to the control group (2.1% vs. 46.6%; RR: 0.05; CI: 0.01-0.32; P<0.001).

S. boulardii CNCM I-745 has also garnered endorsement by various health organizations, reinforcing its value as an adjunctive therapy alongside conventional treatments for AAD, including oral rehydration and anti-diarrheal medications. This makes it a viable option for both pediatric and adult patients managing AAD symptoms.

The only commercially available product containing this strain S. boulardii CNCM I-745 is the over-the-counter supplement Florastor^®.

Florastor – The Clinically Validated Probiotic Pharmacists Can Confidently Recommend by Name

Florastor promotes the growth of one’s own native health-promoting bacteria without colonizing the gut, and it is naturally eliminated within five days after the last dose is taken. It is proven to be resistant to 16 common antibiotics, including broad-spectrum penicillin, cephalosporins, macrolides, and fluoroquinolones, and provides five key benefits that support gastrointestinal health during and after antibiotic use in adults and children:

• Improves Good Gut Balance
  • Promotes normalization of the intestinal flora depleted by antibiotics
  • Binds certain harmful bacteria to the sugar mannose found on the cell wall, preventing adhesion to the intestinal epithelium
  • Enhances short-chain fatty acid production, supplying energy to intestinal epithelial cells
• Promotes Normal Stool Formation
  • Produces proteins that degrade and destroy harmful toxins, reducing water secretion and diarrhea
• Enhances Digestion and Nutrient Absorption
  • Elevates polyamine levels, which promote enterocyte maturation and stimulates digestive enzyme production, improving nutrient and water absorption
• Boosts Immune Function
  • Stimulates IgA production, a key antibody that defends against bacterial and viral infections
• Reduces Gut Inflammation
  • Suppresses pro-inflammatory cytokines, helps to reduce intestinal inflammation and supports mucosal recovery

These effects are supported by a robust body of evidence: Over 1,000 publications, more than 130 clinical trials and over 13 meta-analyses.

A systematic review and meta-analysis conducted by Szajewska, et al.⁴, further supports the efficacy of Florastor’s probiotic strain S. boulardii CNCM I-745, showing a 53% reduction in AAD risk in both adults and children compared to a placebo. The meta-analysis included randomized controlled trials up until the year 2015 that were investigating adults and children who received antibiotic therapy, and where the intervention group received S. boulardii CNCM I-745 at any dose or duration and the control group received a placebo or no treatment.

A total of 21 randomized controlled trials (15 in adults and 6 in children) including 4,780 people met the criteria. Researchers found that in adults the treatment of S. boulardii CNCM I-745 reduced the risk of AAD 72% versus the placebo (from 17.4% to 8.2%; RR: 0.49, 95% CI: 0.38-0.63, NNT: 11, 95% CI: 9-15) and 81% in children versus the placebo (from 20.9% to 8.8%; RR: 0.43, 95% CI: 0.30-0.60, NNT: 9, 95% CI: 7-12). The researchers noted that “one characteristic that makes [this] meta-analysis distinct from other reviews is that it focuses exclusively on only one well-defined probiotic, S. boulardii CNCM I-745; thus, the findings can be directly applied to clinical practice.”

In addition, Florastor is suitable for a wide range of people due to its gluten-free, vegetarian, non-GMO formulation. While it contains some lactose, S. boulardii CNCM I-745 has been shown to stimulate lactase activity, making it suitable for individuals with lactose intolerance. It is also free from common allergens, including corn, peanuts, tree nuts, and shellfish, supporting use in patients with dietary restrictions.

Recommending A Daily Florastor is An Easy Solution to Support GI Wellness

For patients not currently on antibiotics but experiencing gas, bloating, or intermittent diarrhea (like ‘travelers’ diarrhea’) everyday use of Florastor offers an evidence-based option to help restore and maintain gut microbiota balance by boosting the natural good bacteria in the gut.

In addition to its well-established use alongside antibiotics, S. boulardii CNCM I-745 has been shown to support the activity of digestive enzymes like lactase, maltase, and sucrase, potentially beneficial for older adults as enzyme levels may naturally decline with age.

Pharmacists should consider recommending a daily Florastor to patients taking antibiotics, as well as those struggling with GI issues and occasional diarrhea. This proactive approach can support digestive health and help patients feel better fast.

For free samples of Florastor or to learn more, visit FlorastorHCP.com

Important Safety Information

Do not use Florastor or other probiotics in any ICU setting and in those individuals with open arterial and venous access required (such as a Vascath, Permcath, or AV fistula). Do not use for any individual with a central line or port or in the surroundings of any person with a central line or port. [Central lines include short- and long-term central venous catheters (CVCs) and peripherally inserted central catheters (PICCs)]. Do not use Florastor for pre- or post-organ or bone marrow transplant patients and other people considered severely immunocompromised or critically ill. Do not use in pre-term or neonatal infants under 2 months of age. Do not use Florastor probiotics if allergic to any components (especially yeast). Less than 1% of people experience constipation or thirst. Very rarely, side effects such as: allergic reaction (skin rash), fungemia, or sepsis in people with a central venous catheter, and in hospitalized, immunocompromised patients may occur.

For product questions or to report an adverse event, please call 877-356-7787.

This educational information is intended for use by qualified healthcare practitioners only and is not intended for use by consumers or to substitute for appropriate professional care.

1. Shan, L.-S. et al. Prevention and treatment of diarrhoea with Saccharomyces boulardii in children with acute lower respiratory tract infections. BM 4, 329–334 (2013).
2. Huang, H. et al. Antibiotics and antibiotic-associated diarrhea: a real-world disproportionality study of the FDA adverse event reporting system from 2004 to 2022. BMC Pharmacol Toxicol 24, 73 (2023).
3. McFarland LV. Antibiotic-associated diarrhea: epidemiology, trends and treatment. Future Microbiol. 3(5):563-78. (2008).
4. Szajewska, H. & Kołodziej, M. Systematic review with meta‐analysis: Saccharomyces boulardii in the prevention of antibiotic‐associated diarrhoea. Aliment Pharmacol Ther 42, 793–801 (2015).
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8. Edwards-Ingram, L. et al. Genotypic and Physiological Characterization of Saccharomyces boulardii, the Probiotic Strain of Saccharomyces cerevisiae. Appl Environ Microbiol 73, 2458–2467 (2007).
9. Dinleyici, E. C. et al. Saccharomyces boulardii CNCM I-745 reduces the duration of diarrhoea, length of emergency care and hospital stay in children with acute diarrhoea. BM 6, 415–422 (2015).