Florastor can be taken at the same time as your antibiotic, and that’s one of its key advantages over other probiotics. Because Florastor contains a yeast (not bacteria), antibiotics can’t kill it. Most bacterial probiotics need to be separated from antibiotic doses by two to three hours, but Florastor doesn’t have this limitation. That said, there are still best practices for getting the most out of it during your antibiotic course.
Why Florastor Survives Antibiotics
Florastor’s active ingredient is a probiotic yeast called Saccharomyces boulardii. Antibiotics are designed to kill bacteria, not yeast, which makes this strain naturally resistant to every class of antibacterial antibiotic. Studies in both animals and humans have confirmed that taking Saccharomyces boulardii alongside antibiotics like ampicillin actually increases the number of viable yeast cells in the gut. In other words, the antibiotic doesn’t weaken Florastor at all.
This is a meaningful distinction. If you’re taking a standard bacterial probiotic (one containing Lactobacillus or Bifidobacterium strains, for example), you need to space it at least two to three hours away from each antibiotic dose so the antibiotic doesn’t destroy the probiotic bacteria before they reach your gut. Florastor doesn’t require that separation.
Timing and Dosage During Antibiotic Use
The standard adult dose is one capsule twice daily. Start taking Florastor on the same day you begin your antibiotic, and continue for at least a few days after your antibiotic course ends. This gives your gut flora time to begin recovering after the antibiotic pressure is gone.
You can take Florastor with or without food, and you can take it at the same time as your antibiotic dose if that’s simplest for your schedule. Some people find it easiest to pair each Florastor capsule with a meal, taking one in the morning and one in the evening. Consistency matters more than precise timing here.
How to Swallow or Mix Florastor
Capsules can be swallowed whole with at least four ounces of water or juice. If you have trouble swallowing capsules (or you’re giving it to a child), you can open the capsule and mix the contents with a soft food like applesauce or yogurt. You can also stir it into a cold, noncarbonated, nonalcoholic drink like water or juice.
Temperature matters. Saccharomyces boulardii is a living organism, and hot liquids will kill it. Don’t mix the powder into hot coffee, tea, soup, or any warm food. Stick to cold or room-temperature options.
How Well It Works for Antibiotic-Related Diarrhea
The main reason people take Florastor with antibiotics is to prevent the diarrhea that antibiotics commonly cause. Roughly 5 to 25 percent of people on antibiotics develop diarrhea, and the evidence for Florastor’s strain is strong. A systematic review and meta-analysis found that Saccharomyces boulardii reduced the risk of antibiotic-associated diarrhea by 72% in adults compared to placebo, dropping the rate from about 17% down to 8%. In children, the reduction was even larger: 81%, with rates falling from roughly 21% to 9%.
There’s also evidence that Florastor helps protect against C. difficile infections, a more serious complication of antibiotic use. A combined analysis of multiple studies showed that people taking Saccharomyces boulardii had significantly lower rates of C. difficile infection compared to those on placebo.
The One Drug That Does Kill Florastor
Antibiotics won’t harm Florastor, but antifungal medications will. Since Florastor is a yeast, any antifungal drug (like fluconazole or similar medications used for yeast infections, thrush, or fungal infections) will destroy it in the same way an antibiotic destroys bacterial probiotics. If you’re currently taking an antifungal, Florastor won’t be effective.
Who Should Avoid Florastor
Florastor is safe for most people, but there are exceptions. Cases of Saccharomyces fungemia (a yeast bloodstream infection) have been reported in patients who are critically ill, receiving tube feeding, or have a central venous catheter. People who are severely immunocompromised or hospitalized with central lines should not take Florastor without direct guidance from their care team. For generally healthy people taking a course of oral antibiotics at home, this risk does not apply.
People with yeast allergies should also avoid Florastor, since its active ingredient is a yeast strain.