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Florastor Probiotic Review: A Dietitian’s Comprehensive Take

By Ana Reisdorf, MS, RD

Last Updated on January 21, 2022

Medically Reviewed by Anthony Dugarte, MD

Dietitian Rating:


About This Rating
The average rating of this product is calculated based on the evaluation of the following factors:
  • Support for Claims:5.0
  • Ingredient Safety:4.0
  • Value for the Price:4.0
  • Brand Transparency:4.0

Florastor is an effective line of probiotic supplements that contain a patented yeast that has been found in over 600 clinical studies to be beneficial for specific digestive concerns and illnesses.

Written by
Ana Reisdorf, MS, RD
Registered Dietitian Nutritionist
Ana Reisdorf is a registered dietitian nutritionist with 14 years of experience in the field of nutrition and dietetics. She graduated from UCLA in 2002 with a degree in psychology and women’s studies and completed her master’s degree from Central Michigan University in 2010
Medically Reviewed by
Anthony Dugarte, MD
Medical Reviewer
Anthony Dugarte, M.D., C.S.C.S. is a health and wellness writer and medical content reviewer. In addition to dedicating the last 11 years to medical research, Dr. Dugarte also has more than a decade of experience in strength and conditioning, nutrition, and rehabilitative exercise, as well as authoring and reviewing health and wellness-related content.
Florastor Probiotic Review: A Dietitian’s Comprehensive Take
Photo Credit: iStock.com/Petar Chernaev


  • Extensively researched ingredient with over 600 clinical studies
  • Safe for babies two months and above
  • Does not need refrigeration


  • Higher price-point compared to other probiotics
  • Not lactose or soy-free
  • Only provides one strain of yeast, no other bacterial strains

What Is Florastor Daily Probiotic?

Florastor is a line of yeast-based probiotic supplements geared towards specific ages and health concerns. They have five products:

  • Florastor Daily Probiotic
  • FlorastorKids Daily Probiotic
  • FlorastorBaby Daily Probiotic
  • FlorastorSelect Gut Boost
  • FlorastorSelect Immunity Boost

Florastor is different from most probiotic supplements because it doesn’t contain any bacteria.

Most supplements have one or more types of healthy bacteria. These bacteria are meant to increase the levels of good bacteria in the gut, which may help address digestive and health concerns.

Florastor takes a different approach. Its products contain a proprietary strain of yeast called Saccharomyces boulardii CNCM I-745. 

This yeast doesn’t colonize the gut. Instead, it has several physiological actions to protect the gut from bad bacteria and normalize the good bacteria.

S. boulardii was discovered in the 1920s by a French engineer and microbiologist.

Upon a visit to Indonesia, he noticed that locals that drank a type of tea made from mangosteen and lychees seemed to be immune to cholera, an illness that causes severe diarrhea.

What he found upon further evaluation is that the skins of these two fruits contained the yeast S. boulardii.

Once he isolated this yeast and began to discover its benefits, a French company patented the strain and enhanced it to pharmaceutical quality.

This is when S. boulardii CNCM I-745 was born. The specificity of this strain is important because probiotics tend to behave in a strain-specific manner. 

It was the first probiotic to be used intentionally for human health and has been part of over 600 clinical trials.

Florastor is the only product in North America that contains this beneficial yeast.

Evaluation of Ingredients

Since all Florastor Daily Probiotic supplements contain S. boulardii CNCM I-745, it is important to evaluate this ingredient before moving on to the different products Florastor offers.

Saccharomyces boulardii CNCM I-745, 250 mg per capsule, 5 billion CFUs

As previously mentioned, S. boulardii CNCM I-745 has been the subject of over 600 clinical studies. Its primary benefit is its ability to support gut health by preventing bacterial infections and improving inflammatory conditions in the gut. (1)

Florastor has a section on their website for “health professionals” with videos that explain precisely how S. boulardii supports gut health.

I found these videos to be informative and very helpful in understanding the exact mechanism of how this yeast words in the gut.

Here is a simple breakdown of the three ways this yeast helps:

  • Prevention (Luminal): S. boulardii releases proteins against specific toxins created by harmful bacteria that cause diarrhea and inflammation. This neutralizes the toxins before they cause infection. Bad bacteria also adhere to the cell walls of S. boulardii, preventing them from entering the body. It also supports the health of good bacteria that already exist in the gut through the release of short-chain fatty acids the bacteria love to eat.

  • Gut Lining (Trophic): S. boulardii protects the gut lining by supporting the health of the cells and villi, preventing bad bacteria from entering, and stimulating immune cells in the gut lining.

  • Inside the Gut Wall (Mucosal): S. boulardii helps lower inflammation by decreasing inflammatory compounds.

Due to these specific actions of S. boulardii, several studies have found it to be beneficial for gut health and treating specific infections.

With over 600 studies on the benefits of this particular yeast strain, it can be a challenge to sort through all the research.

A 2019 review is one of the most recent research summaries on its potential benefits. This review found that this specific strain of S. boulardii is beneficial for: (2)

  • Prevention of antibiotic-associated diarrhea in children and adults
  • Treating colitis and C. difficile diarrhea (challenging to treat with antibiotics)
  • Treating patients with general viral, bacterial, or parasitic infection of the gut
  • Reducing the duration of diarrhea and hospitalization due to gastrointestinal infections
  • Decreasing the risk of travelers diarrhea caused by coli, C.jejuni, Salmonella, and others
  • Protecting against infection by pylori, a major cause of gastric ulcers

One thing to note about S. boulardii is that it doesn’t change the composition of the gut microbiome. Instead, it helps the microbiome return to normal after infection and helps prevent infections from occurring in the first place.


S. boulardii CNCM I-745 has been found to be clinically effective for the prevention and treatment of multiple gastrointestinal illnesses.

Evaluation of the Product Line

Florastor Daily Probiotic

The Daily Probiotic contains 500 mg of S. boulardii or 10 billion colony forming units (CFUs) in 2 capsules daily, divided between breakfast and dinner.

One package only contains 20 capsules, enough for 10 days.

The Florastor Daily Probiotic is a simple, single-ingredient, but evidence-based product.

It would be ideal for someone who has just completed a round of antibiotics, wants to avoid traveler’s diarrhea, or to be used in combination with medical treatments for digestive illnesses.

FlorastorKids Daily Probitoic

The kid’s product is the same as the adult version, but it is just in a powdered form meant to be added to beverages. It is also slightly sweetened with a tutti-fruity flavor and can be easy to sneak into a child’s juice or water.

One sachet provides 250 mg of S. boulardii and is meant to be taken twice a day.

The FlorastorKids product is a great option for a child who has just finished a round of antibiotics or had a gastrointestinal infection to help normalize the gut microbiome.

FlorastorBaby Daily Probiotic

This product has the same ingredients as the kids and adult versions, but it is just available in a flavorless powder designed to be easily mixed into a bottle.

The label also specifies the amount of lactose in the product (32.5 mg) but states that those who are lactose intolerant can still use this product.

The reason is that the S. boulardii is meant to stimulate digestive enzymes to promote the digestion of lactose, improving tolerance.

If your baby is sensitive to lactose, I would recommend proceeding with caution or speaking to your pediatrician first.

FlorastorBaby is a good option for a baby that has just finished a round of antibiotics or is struggling with diarrhea.

As with any supplement, always speak to your pediatrician first to see if it is right for your baby.

FlorastorSelect Gut Boost

Gut Boost contains S. boulardii and a prebiotic fiber called inulin, found in chicory root.

Prebiotics feed healthy gut bacteria. This product would be ideal for someone looking to support overall gut health.

With the addition of the prebiotics, this product leans more towards supporting overall gut health rather than just addressing illness or post-antibiotic diarrhea.

The higher price point makes it a challenge to be used regularly to support general gut health.

FlorastorSelect Immunity Boost

Immunity Boost contains S. boulardii, vitamin C, zinc, and vitamin D.

S. boulardii can support immune health, but the addition of these nutrients helps make this product even more beneficial for immunity.

A review of micronutrients found these three nutrients to be the most beneficial for supporting immune health. (3)

For two capsules, Immunity Boost provides appropriate clinically effective dosages of each:

  • Vitamin C: 120 mg
  • Vitamin D: 800 IU
  • Zinc: 20 mg

Overall, Immune Boost provides additional vitamins and minerals in clinically effective dosages to help further support immune health.

Support for Claimed Benefits

Below is our summary of the available evidence for the claimed benefits of Florastor based on the available research:

Maintains digestive balance by flushing out bad bacteria5/5
Breaks down carbs and sugar for better digestion5/5
Withstands harsh stomach environment5/5
Stimulates immunity5/5
Thrives even during antibiotic use5/5
Destroys toxins from harmful bacteria5/5
Naturally strengthens digestive system5/5

With over 600 clinical studies on S. boulardii CNCM I-745, there is ample evidence and clinical understanding of its actions and benefits for digestive health.

Side Effects, Safety, and Dosage

The dosage for all Florastor products is two capsules or sachets twice per day.

S. boulardii is generally considered safe. As with any probiotics, common side effects are gas, bloating, and diarrhea. (4)

It may also cause fungal infections in the elderly or in people with a suppressed immune system, but the currently available research is a case report involving only one subject. (5)

People with yeast or soy allergies should avoid this product.

As mentioned previously, Florastor does contain lactose. If you have lactose intolerance, your digestive symptoms may worsen, but this will likely depend on the individual.

Since Florastor does make products for children and infants, it is always best to speak to your pediatrician before giving a probiotic to your child.

Adults should also speak to their doctor before trying any dietary supplement.


The Florastor products are expensive for a probiotic.

  • Florastor Daily Probiotic: $19.99 for a 10-day supply
  • FlorastorKids Daily Probiotic: $19.99 for a 10-day supply
  • FlorastorBaby Daily Probiotic: $19.99 for a 10-day supply
  • FlorastorSelect Gut Boost: $34.99 for a 2-week supply
  • FlorastorSelect Immunity Boost: $34.99 for a 2-week supply

Most quality probiotics cost between $20–$30 per month – less than half the price of Florastor.

But most alternative products do not contain the specialized, clinically effective yeast found in Florastor.

Since Florastor is a unique product not found anywhere else on the market in North America and is effective for preventing and treating illness, it is likely worth the cost in the short term.

How Florastor Compares to Alternatives

While there are many probiotics on the market, even ones containing S. boulardii, none include S. boulardii CNCM I-745, the specific strain used in clinical research.

Since alternative products do not use this specific strain, the benefits cannot be translated.

Other clinically effective products on the market work in slightly different ways compared to Florastor and contain different bacterial strains.

These are designed to increase the number of specific bacteria in your gut, not prevent infection or inflammation.


VSL#3 is a probiotic commonly used to treat symptoms of irritable bowel syndrome. It contains a blend of bacteria that has been found to be beneficial for this condition, which can cause diarrhea.

VSL#3 is less expensive than Florastor, at about $63 for a 60-day supply, if you take one capsule daily.

Klaire Labs Ther-Biotic Complete

Klaire Labs Ther-Biotic Complete helps treat diarrhea with different strains of Lactobacillus, which have also been found to be beneficial for gut health.

Klaire Labs is also less expensive than Florastor at $49.99 for a 60-day supply.

While these products are less expensive, none work exactly like Florastor; therefore, nothing on the market is exactly comparable.

The Bottom Line

While the specific strain of S. boulardii in Florastor has been extensively clinically evaluated for diarrhea and GI illness, with just one strain in the product, it may not resolve every digestive ailment.

Therefore, I would recommend Florastor after a round of antibiotics to help normalize gut health. It may also be worth trying if you are visiting a place where traveler’s diarrhea is common.

If you have ongoing digestive problems, especially diarrhea, it is best to speak to your doctor, who can provide a treatment plan for you.

Overall, Florastor is an evidence-backed, effective product for digestive health.

Next Steps

If you are interested in trying Florastor for diarrhea caused by antibiotics or other digestive ailments, you can make other lifestyle changes that may help.

Consider including fermented foods like kombucha or yogurt in your diet to help improve gut health. Drink plenty of water to stay hydrated, at least 8 glasses per day.

Avoid foods that upset your stomach. Common food intolerances include dairy and foods containing FODMAPs, fermentable sugars that can make symptoms work.

Aim to eat at least 25–35 grams of fiber per day, which can help normalize bowel movements and feed healthy gut bacteria.

If you think you have IBS or other gut illnesses, work with a doctor or registered dietitian to rule out underlying conditions, food allergies, and intolerances.

If your diarrhea is severe or you are getting dehydrated, always seek medical attention.

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At WellnessVerge, we only use reputable sources, including peer-reviewed medical journals and well-respected academic institutions.

  1. Efficacy and safety of the probiotic Saccharomyces boulardii for the prevention and therapy of gastrointestinal disorders:
  2. Diversity of Saccharomyces boulardii CNCM I-745 mechanisms of action against intestinal infections:
  3. A Review of Micronutrients and the Immune System-Working in Harmony to Reduce the Risk of Infection:
  4. Effect of Supplementation with Saccharomyces Boulardii on Academic Examination Performance and Related Stress in Healthy Medical Students: A Randomized, Double-Blind, Placebo-Controlled Trial:
  5. Saccharomyces cerevisiae fungemia in a critically ill patient with acute cholangitis and long term probiotic use: