Key takeaways:
If you already have acute diarrhea from an infection, probiotics probably won’t do much to shorten it.
For this reason, probiotics aren’t generally recommended as a treatment. But probiotics may help prevent certain types of diarrhea. For example, some probiotics may help lower the risk of diarrhea caused by taking antibiotics.
If you have diarrhea, staying hydrated is more important than taking a probiotic.
Talk with a healthcare professional if your diarrhea lasts more than a few days or comes with symptoms such as blood in your stool, intense pain, or signs of dehydration.
When you have diarrhea, you probably want it to stop as quickly as possible. So it’s natural to wonder whether taking a probiotic could help.
Probiotics are live microorganisms that may provide health benefits when taken in certain amounts. They’re often marketed as a way to support a healthy gut. But when it comes to diarrhea, their benefits depend on the type of probiotic and whether you’re trying to treat diarrhea that has already started or prevent it in the first place.
Here’s what to know before reaching for a probiotic supplement for diarrhea.
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Should you take probiotics when you have diarrhea?
Probably not. If you already have diarrhea, probiotics may not do much to treat it.
Some earlier studies suggested that probiotics might shorten diarrhea caused by infection by about a day. But newer, higher-quality studies haven’t found a clear benefit. So experts don’t routinely recommend probiotics for children with acute infectious gastroenteritis, one of the most common causes of diarrhea.
That said, it’s possible that probiotics may help prevent certain kinds of diarrhea before they start.
When might probiotics help diarrhea?
While probiotics aren’t likely to help much once diarrhea has started, they may help prevent certain types of diarrhea or improve symptoms in some digestive conditions.
Diarrhea caused by antibiotics
Probiotics may be most helpful for preventing diarrhea caused by antibiotics. Antibiotics can disrupt the balance of bacteria in your gut, which can lead to loose stools. Research suggests that certain probiotics may lower the risk of antibiotic-associated diarrhea. In studies, children who took probiotics along with antibiotics were less likely to develop diarrhea.
Diarrhea associated with Clostridium difficile infection
Probiotics may also help lower the risk of Clostridium difficile (C. diff), a more serious, highly contagious infection that can cause diarrhea and sometimes develops after taking antibiotics.
This potential benefit appears to be greatest in people at higher risk for C. diff, such as some older adults or hospitalized people who are taking certain antibiotics. Probiotics don’t appear to make much difference for people at low or moderate risk.
Diarrhea associated with irritable bowel syndrome
Irritable bowel syndrome (IBS) is a common digestive condition that can cause bloating, gas, stomach cramps, and changes in bowel movements. One common type of IBS is IBS-D, which causes frequent diarrhea.
Probiotics may improve some symptoms in people with IBS-D. In one study, participants took probiotics daily for 8 weeks. Compared to participants who took a placebo, they had improved overall IBS symptoms, including fewer loose or watery stools. But other evidence is less clear about whether probiotics can meaningfully improve diarrhea itself in people with IBS-D.
How do probiotics work for diarrhea?
Probiotics may help with diarrhea in several ways, including:
Crowding out harmful bacteria: Probiotics can compete with harmful bacteria for food and space in the gut. This can make it harder for harmful bacteria to grow and multiply.
Creating an unfriendly environment for harmful bacteria: Some probiotics produce acids and other substances that can slow the growth of diarrhea-causing bacteria.
Strengthening the gut barrier: Probiotics may help support the lining of the intestines, which helps control how water, electrolytes, nutrients, and other compounds move between the gut and the rest of the body.
Regulating inflammation: Some probiotics may influence the immune response in ways that help reduce inflammation in the gut.
Which are the best probiotics for diarrhea?
There isn’t a single best probiotic for diarrhea. Different strains have been studied for different causes and situations.
Here are some strains that have been studied:
Antibiotic-associated diarrhea: Lactobacillus rhamnosus (L. rhamnosus) and Saccharomyces boulardii (S. boulardii) are among the best studied probiotics for preventing antibiotic-associated diarrhea. Studies suggest that higher doses — more than 5 billion colony-forming units (CFU) per day — may be more effective.
C. diff diarrhea: S. boulardii and combinations containing Lactobacillus acidophilus (L. acidophilus) and Lacticaseibacillus casei (L. casei) may help lower the risk of C. diff-associated diarrhea in some people. The benefit may depend on the specific probiotic, the dosage, and an individual’s underlying risk.
IBS with diarrhea: The evidence for probiotics in IBS-D is less certain. Some probiotic strains — including Lactiplantibacillus plantarum (L. plantarum), Bifidobacterium longum (B. longum), Saccharomyces cerevisiae (S. cerevisiae), and Bacillus coagulans (B. coagulans) — have been linked with improvements in IBS symptoms. But that doesn’t necessarily mean they specifically improve diarrhea in everyone with IBS-D.
Keep in mind that over-the-counter (OTC) supplements — including probiotics — aren’t regulated by the FDA in the same way medications are. When choosing a probiotic supplement, look for one that’s been third-party tested. This can provide some assurance that the product contains what the label says, and has been tested for certain contaminants. But third-party testing doesn’t mean that the probiotic has been proven to prevent or treat diarrhea.
Can probiotic foods help with diarrhea?
Foods that contain live cultures, such as certain yogurts and other fermented foods and drinks, may support gut health. But they’re not necessarily equivalent to probiotic supplements that have been studied for diarrhea.
That’s because the type and amount of live microorganisms in fermented foods can vary widely — and sometimes isn’t even known at all. It also depends on how much of the food you eat, and how often you eat it. In contrast, probiotic supplements can provide a more consistent dose of specific strains because they’re formulated to contain a set amount.
So you can’t assume that eating a serving of kimchi or yogurt will provide the same benefits as a probiotic supplement used in a clinical study. That said, probiotic foods can provide valuable nutrients, and foods with live cultures may support a healthy gut.
Foods that may contain live cultures include:
When to get help for diarrhea
Most short-term diarrhea gets better within a few days. But diarrhea can sometimes be a sign of a more serious infection or another condition that needs treatment.
Get medical care if you have:
Diarrhea that doesn’t improve after a few days
Diarrhea that keeps coming back or lasts for several weeks
Blood or pus in your stool
Black, tarry stools
Intense or persistent abdominal pain
A high fever
Frequent vomiting or trouble keeping fluids down
Signs of dehydration, such as very little urination, dizziness, or extreme thirst
Children, older adults, and people with certain medical conditions can become dehydrated more quickly. They may need medical attention sooner.
Frequently asked questions
You can usually take probiotics along with other diarrhea treatments, such as an oral rehydration solution. Depending on the cause of your diarrhea, you may also be able to take an over-the-counter (OTC) medication to help manage symptoms. To be clear, probiotics aren’t a substitute for treatment. For example, some bacterial infections may need antibiotics, while dehydration may require fluids and electrolytes.
Probiotics are generally considered safe for most healthy people. But they can cause temporary digestive symptoms, such as gas, bloating, or diarrhea, especially when you first start taking them. Research suggests that some groups of people may be at a higher risk of side effects from taking probiotics.
You can usually take probiotics along with other diarrhea treatments, such as an oral rehydration solution. Depending on the cause of your diarrhea, you may also be able to take an over-the-counter (OTC) medication to help manage symptoms. To be clear, probiotics aren’t a substitute for treatment. For example, some bacterial infections may need antibiotics, while dehydration may require fluids and electrolytes.
Probiotics are generally considered safe for most healthy people. But they can cause temporary digestive symptoms, such as gas, bloating, or diarrhea, especially when you first start taking them. Research suggests that some groups of people may be at a higher risk of side effects from taking probiotics.
Speak with a healthcare professional before taking them if you have a weakened immune system or are otherwise at higher risk for infection. Parents and caregivers should also check with a medical professional before giving probiotics to babies or young children.
The bottom line
Probiotics aren’t a magic fix for diarrhea. They aren’t likely to help much with acute diarrhea that’s already started. But certain strains may help prevent antibiotic-associated diarrhea or improve symptoms in some people with a common type of irritable bowel syndrome (IBS) that causes frequent diarrhea, known as IBS-D. If you have diarrhea, prioritize staying hydrated. And be sure to talk with a healthcare professional if symptoms are severe or keep coming back.
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References
Collinson, S., et al. (2020). Probiotics for treating acute infectious diarrhoea. Cochrane Database of Systematic Reviews.
Esmaeilinezhad, Z., et al. (2025). Probiotics for the prevention of Clostridioides difficile‐associated diarrhea in adults and children. Cochrane Database of Systematic Reviews.
Guo, Q., et al. (2019). Probiotics for the prevention of pediatric antibiotic‐associated diarrhea. Cochrane Database of Systematic Reviews.
Kopacz, K., et al. (2022). Probiotics for the prevention of antibiotic-associated diarrhea. Healthcare.
Martoni, C. J., et al. (2023). Efficacy and dose response of Lactiplantibacillus plantarum in diarrhea-predominant irritable bowel syndrome. World Journal of Gastroenterology.
Maslennikov, R., et al. (2026). Strain-specific systematic review with meta-analysis of probiotics efficacy in the treatment of irritable bowel syndrome. Journal of Clinical Medicine.
Merenstein, D., et al. (2023). Emerging issues in probiotic safety: 2023 perspectives. Gut Microbes.
Preidis, G. A., et al. (2014). Targeting the human microbiome with antibiotics, probiotics, and prebiotics: Gastroenterology enters the metagenomics era. Gastroenterology.
Su, G. L., et al. (2020). AGA clinical practice guidelines on the role of probiotics in the management of gastrointestinal disorders. Gastroenterology.
Wang, Y., et al. (2022). Probiotics therapy for adults with diarrhea-predominant irritable bowel syndrome: a systematic review and meta-analysis of 10 RCTs. International Journal of Colorectal Disease.
