Is NOW Foods Saccharomyces (S.) boulardii as effective as Florastor (Saccharomyces boulardii)?

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Last updated: July 3, 2025View editorial policy

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From the Guidelines

NOW Foods Saccharomyces boulardii is likely as effective as Florastor since both contain the same probiotic strain, Saccharomyces boulardii, as supported by the AGA clinical practice guidelines on the role of probiotics in the management of gastrointestinal disorders 1. The key factor is ensuring you're getting a comparable dose of viable organisms. Florastor typically contains 250-500 mg of S. boulardii per capsule (approximately 5-10 billion CFUs), while NOW Foods S. boulardii typically provides 5 billion CFUs per capsule. For equivalent effects, you would need to match the dosage. Some key points to consider when using S. boulardii include:

  • S. boulardii is a beneficial yeast that helps maintain healthy intestinal flora, particularly during antibiotic use or digestive disturbances.
  • It works by competing with harmful microorganisms, strengthening intestinal barriers, and modulating immune responses.
  • Both products should be stored properly according to package instructions to maintain potency.
  • If you're switching between brands, maintain the same dosage schedule as recommended for your specific condition, typically 1-2 capsules 1-2 times daily.
  • Consult a healthcare provider before use, especially if you have a compromised immune system or yeast sensitivities, as suggested by the AGA technical review on the role of probiotics in the management of gastrointestinal disorders 1. It's also important to note that the AGA suggests the use of S. boulardii in adults and children on antibiotic treatment for the prevention of C. difficile infection, with a conditional recommendation and low quality of evidence 1. However, the overall quality of evidence for the use of probiotics in gastrointestinal disorders is generally low, and more research is needed to fully understand their effects, as highlighted in the AGA clinical practice guidelines 1.

From the Research

Comparison of NOW Foods S. boulardii and Florastor

  • Both NOW Foods S. boulardii and Florastor contain the yeast Saccharomyces boulardii, which has been shown to be effective in preventing antibiotic-associated diarrhea and Clostridium difficile diarrhea 2, 3, 4.
  • Studies have demonstrated that S. boulardii can reduce the risk of antibiotic-associated diarrhea and recurrent C. difficile infection in adults 3, 5, 4.
  • However, the efficacy of S. boulardii in preventing primary C. difficile infection is less clear, with some studies showing a trend towards reduction but lacking statistical significance 6, 5.
  • The effectiveness of S. boulardii may depend on the specific patient population, concurrent antibiotic treatment, and dosage used 5, 4.
  • Both products contain the same active ingredient, but the quality, manufacturing process, and dosage may differ between NOW Foods and Florastor.
  • There is no direct comparison study between NOW Foods S. boulardii and Florastor, but both products contain S. boulardii, which has been shown to be effective in preventing antibiotic-associated diarrhea and C. difficile diarrhea 2, 3, 4.

Key Findings

  • S. boulardii has been shown to be effective in preventing antibiotic-associated diarrhea and recurrent C. difficile infection in adults 3, 5, 4.
  • The efficacy of S. boulardii in preventing primary C. difficile infection is less clear 6, 5.
  • S. boulardii is generally well-tolerated, but may cause adverse effects such as thirst and constipation 5.
  • Further study is needed to fully establish the efficacy and optimal dosage of S. boulardii for preventing antibiotic-associated diarrhea and C. difficile diarrhea 3, 4.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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