How Probiotics Can Help Manage Diarrhea

Written by: Kari Raman, PharmD, RPh
Published May 29, 2023

As an experienced pharmacist, I frequently field questions about the role of probiotics in managing gastrointestinal issues, particularly diarrhea. Patients are increasingly interested in the potential of these “good bacteria” to manage a variety of digestive problems. One of the most intriguing areas of research is the potential use of probiotics to treat and prevent diarrhea. Yes, we’re talking about diarrhea, so let’s dive into the gut of the matter – Yup, that’s a pharmacist pun. I’ll probably stick with my day job.

Unraveling the Mystery of Probiotics

Probiotics are live bacteria and yeasts that, in quite a few situations, can contribute to our health, particularly our digestive system. It might seem counterintuitive that bacteria could be beneficial, but your body is home to billions of these microbes, many of them beneficial. Certain strains of probiotics seem to be particularly effective in managing diarrhea, and I’ll delve into this in more detail.

Probiotics are an area where the pace of research that I’m seeing come out is pretty amazing. I actually started this blog in an attempt to try to keep up with all the research that I’m seeing. Researchers are finding ways that the gut, and the microbiome, are contributing to all sorts of health issues. For example, after you are done reading about diarrhea, check out my article on “can probiotics help make you feel happy.” Although, I would argue that if your gut is causing you a lot of pain, you aren’t going to be as happy as you can be.

6 Probiotics in the Spotlight for Diarrhea Management

  1. Lactobacillus rhamnosus GG: L. rhamnosus is one of the most extensively studied probiotics and has shown promising results in managing diarrhea. Studies have demonstrated its efficacy in reducing the duration of acute infectious diarrhea in children and adults, as well as preventing antibiotic-associated diarrhea. The medical research suggests that this is one of the most promising for treating this condition.
  2. Lactobacillus acidophilus: L. acidophilus is a friendly resident in our intestines and vagina, keeping harmful bacteria under control. Some studies have indicated that L. acidophilus can reduce the duration and severity of diarrhea in children.
  3. Lactobacillus casei: Yet another member of the Lactobacillus family, L. casei has been shown to have a protective effect in treating antibiotic-associated diarrhea and diarrhea in children.
  4. Bifidobacterium spp: Found naturally in the intestines and breast milk, Bifidobacterium spp has been used to treat several bowel conditions including diarrhea. Particularly, Bifidobacterium bifidum and Bifidobacterium longum have demonstrated effectiveness in managing antibiotic-associated diarrhea.
  5. Streptococcus spp: Streptococcus thermophilus, a strain of Streptococcus spp, has shown effectiveness in managing diarrhea. Specifically, it can help reduce the duration of acute diarrhea in infants and children. The value of Streptococcus spp in probiotic therapy lies in its resilience, allowing it to withstand the harsh conditions of the digestive system and deliver its benefits effectively.
  6. Saccharomyces boulardii: I listed this one last because it’s not a bacterium but a friendly yeast. S. boulardii has been proven effective in the treatment and prevention of antibiotic-associated diarrhea and traveler’s diarrhea. Its mechanism of action is fascinating as it appears to work by inhibiting harmful bacterial toxins and stimulating the body’s immune response, hence showing efficacy in managing diarrhea. This is the other top probiotic for treating this condition.

I’ll dig into the science behind the selected probiotics above later. 

Taking the Right Probiotics for Diarrhea Management

In my experience, generic probiotics really don’t do much for the treatment of diarrhea – you need to pay attention to what and how you take the supplement. And, it can take 7 to 10 days for a probiotic to successfully colonize your gut, so this means that I always recommend that patients stick with the supplementation for a while before expecting results. However, the best options I mention here may take about 2 to 3 days for probiotics to start to improve diarrhea. Here are some ways to pick the right probiotic to help treat this condition:

1. Read the label: Check for the genus, species, and strain of the probiotic. In addition, look for the number of organisms contained in a single dose, often denoted in Colony Forming Units (CFUs). 

2. Understand your needs: The choice of probiotic is based on your specific health condition. Different strains have different effects, so it’s crucial to match the probiotic strain to the health outcome you desire.

3. Professional advice: Severe diarrhea is a serious problem. Consult with healthcare professionals like your pharmacist or physician to guide you through the process and ensure you’re making an informed choice. Please read the next section where I lay out some of the times you’d want to consult with a doctor. Remember, if you think you need to see a doctor you probably do, so make that appointment! 

Probiotics can’t fix all diarrhea

I always remind my patients: you should see a doctor if you have diarrhea that lasts more than 2 days, is accompanied by fever, blood, or mucus, or is severe enough to keep you from going to work or school. There are other reasons that you’d want to talk to a doctor if you have diarrhea: if you are pregnant, have a weakened immune system, or are taking certain medications.

Here are some other reasons why you might need to see a doctor for diarrhea:

  • You have a history of diarrhea-related complications, such as dehydration or electrolyte imbalance.
  • You are taking medication that can cause diarrhea, such as antibiotics or chemotherapy.
  • You have recently traveled to a country where diarrhea is common.
  • If you are concerned about your diarrhea, it is always best to see a doctor to rule out any underlying medical conditions.

Here are some tips to help prevent diarrhea:

  • Wash your hands often with soap and water, especially after using the toilet, changing diapers, or before eating.
  • Avoid contact with people who are sick with diarrhea.
  • Cook food thoroughly.
  • Avoid drinking water from streams or rivers.
  • If you are traveling to a country where diarrhea is common, drink bottled water and avoid ice cubes.
  • Eat a healthy diet with the right balance of fibers
  • Take a quality probiotic supplement with active probiotics known to help with diarrhea

Ok, now for the hardcore science part:

Scientific research on probiotics and diarrhea

Let’s dive into some of the research I reviewed to write this article. I’ll start with the two strains that show the most potential, L. rhamnosus GG and Saccharomyces boulardii. 

Lactobacillus rhamnosus GG (LGG): A large body of evidence from 11 studies involving around 2,444 participants suggests that LGG is effective in treating infectious diarrhea. The most effective daily dosage observed was at least 10 billion Colony Forming Units (CFU). Interestingly, this probiotic reduced the duration of acute infectious diarrhea by approximately a day. However, two subsequent trials found that LGG, taken alone or with another probiotic, L. helveticus R0052, wasn’t more effective than a placebo in treating or improving outcomes of acute gastroenteritis in infants and young children. Despite these mixed results, the European Society for Pediatric Gastroenterology, Hepatology, and Nutrition recommends LGG, typically at doses of 10 billion CFU per day for 5-7 days, as an adjunct to rehydration for managing acute infectious diarrhea in pediatric patients.

Saccharomyces boulardii: This friendly yeast also has supportive research behind it. A review of 22 studies with about 2,440 children aged between 1 month and 15 years found that Saccharomyces boulardii reduced both the duration and frequency of diarrhea. The most commonly used doses were between 1 to 10 billion CFU per day for 5 to 10 days. Similar to LGG, Saccharomyces boulardii also reduced the duration of acute infectious diarrhea by approximately one day. Based on this evidence, the European Society for Pediatric Gastroenterology, Hepatology, and Nutrition recommends Saccharomyces boulardii, typically at doses of 250-750 mg per day (equivalent to 1-10 billion CFU) for 5-7 days, as a helpful supplement alongside rehydration for managing acute infectious diarrhea in pediatric patients.

This presentation in the Journal of Clinical Gastroenterology summarizes research from many different sources, and gets into Lactobacillus acidophilus, Lactobacillus casei, Bifidobacterium ssp, Streptococcus ssp performed in a number of clinical trials. The paper says, “In general, most of these trials do show clear evidence of efficacy, with the 2 most effective strains being Lactobacillus GG and S. boulardii.” 


For many patients, probiotics can be an effective tool in managing diarrhea when used correctly. I recommend to my patients that they see a doctor if they are having serious problems, but that probiotics can be a helpful supplement to improve their digestive health. 

It’s fascinating to see the science unfolding as we deepen our understanding of the gut microbiota and its impact on our health. Remember, though, that probiotics are not a cure-all. A balanced diet, regular exercise, and good hydration remain essential components of a healthy lifestyle. Photo by Giorgio Trovato on Unsplash

Pharmacist Kari Raman

I’m Kari Raman PharmD, RPh, and I am a licensed, practicing pharmacist. I hold a Doctorate in Pharmacy from The University of the Pacific, and I’ve served patients in retail, compounding and hospital pharmacies.

Probiotics are confusing!

One of the most common questions I get asked by patients is about probiotics. And the truth is, probiotics are not as well understood by the healthcare community as they should be.

So I’ve been reading a lot of probiotic clinical trials, and sharing what I’m learning here.

I hope Pharmacist Probiotics helps you find out if there is a type of probiotic that works for you!