Key takeaways:
Probiotics contain live bacteria or yeast that can help support digestive health. Their effects depend on the specific strain and the reason you’re taking them.
Probiotics can sometimes cause temporary diarrhea, especially when you first start taking them. Gas, bloating, and stomach cramps can also occur.
These symptoms are usually mild and improve as your body adjusts. Follow the product instructions and stop taking it if your symptoms are severe or don’t improve.
Probiotics are popular supplements that many people take to support their gut health. They can help balance the microorganisms in your digestive tract. They may also improve symptoms of certain digestive conditions, like irritable bowel syndrome (IBS).
But with all these effects on your gut, you may be wondering: Can probiotics cause diarrhea? The short answer is yes. Probiotics can sometimes cause temporary diarrhea, especially when you first start taking them. Let’s look at why this happens and what you can do about it.
What are probiotics?
Probiotics are live microorganisms that may provide different health benefits. Most are bacteria, but some are yeasts. Probiotics are available as dietary supplements and in some fermented foods (like yogurt or sauerkraut).
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How probiotics work in the body
Trillions of helpful microorganisms naturally live in your digestive tract. Together, they make up your gut microbiome. These microorganisms help your body:
Digest and absorb food
Support your immune system
Keep harmful microorganisms from growing
Produce certain vitamins (including some B vitamins and vitamin K)
Probiotics add beneficial microorganisms to your digestive tract. Depending on the strain, they may also help support the gut barrier or limit the growth of harmful microorganisms. Their effects are usually temporary and vary by probiotic strain.
Can probiotics cause diarrhea?
Yes, probiotics can sometimes cause temporary diarrhea when you first start taking them. They may also cause other bowel changes, like:
These symptoms are usually mild and temporary. And it’s not always clear whether the probiotic itself caused them. In a review of clinical trials, probiotics didn’t increase the overall risk of side effects compared with placebo or no treatment.
Probiotics are also sometimes used to treat constipation. They make stools softer and more frequent, and this can feel like diarrhea if you were constipated before taking them.
Why do probiotics cause diarrhea?
It’s not clear exactly why probiotics may cause temporary diarrhea. Probiotics introduce new microorganisms that can influence your gut microbiome and intestinal transit. In some people, these changes may lead to looser or more frequent stools. These effects can vary by probiotic strain and person.
How can you manage diarrhea from probiotics?
Temporary diarrhea may improve as your body adjusts to taking the probiotics. In the meantime, here are a few things to try if you’re experiencing diarrhea:
Stop the probiotics for a few days to see if your symptoms improve.
Take a smaller dose.
Take the probiotic with food (if the product instructions allow).
Try a different probiotic strain or product.
Drink plenty of fluids to prevent dehydration.
Stop taking the probiotic if your diarrhea is severe or lasts more than a few days. Contact a healthcare professional if you also have a fever, bloody stools, or signs of dehydration.
What is the best way to take probiotics?
There isn’t one best way to take probiotics. Their effects depend on the strain, dose, and reason you’re taking them. The product’s form — like capsule, powder, or drink — may be less important.
Stomach acid can destroy some probiotic microorganisms before they reach the intestines. Some products use protective coatings or other technology to improve their survival during digestion. But research hasn’t established that coated products (or any other formulation) provide greater health benefits.
For best results when taking a probiotic, aim to do the following:
Choose a probiotic containing a strain and dose studied for your specific health concern.
Follow the label’s directions about whether to take it with food.
Check the expiration date and storage instructions (some probiotics require refrigeration).
Take it consistently for the recommended amount of time.
Can you take too many probiotics?
There’s no established maximum dose of probiotics. Many supplements contain 1 billion to 10 billion colony-forming-units (CFUs) per dose, although some contain 50 billion CFUs or more. But a higher CFU coin doesn’t necessarily make a probiotic more effective.
More strains aren’t necessarily better either. Some research favors single-strain probiotics, while other studies suggest that multistrain products may work better. Overall, there isn’t enough evidence to say that one’s consistently more effective than the other.
Follow the dose on the product label. Taking more than the recommended dose may increase digestive symptoms without providing additional benefits.
Probiotics are generally safe for healthy people. But they have occasionally caused serious infections in people who are severely ill or have weakened immune systems. Talk with a healthcare professional before taking probiotics if you fall into either group.
What are the benefits of taking probiotic supplements?
Certain probiotics may provide specific health benefits. Research suggests that they may:
Lower the risk of antibiotic-associated diarrhea
Possibly lower the risk of a Clostridioides difficile (C. diff) infection
Help treat IBS symptoms
Improve stool frequency and consistency in people with constipation
Lower the risk of eczema in some children when used during pregnancy and infancy
Help with symptoms of lactose intolerance
Researchers are still studying probiotics for many other conditions, ranging from obesity to the common cold. Keep in mind that a probiotic that helps with one condition may not help with another.
Frequently asked questions
Taking more probiotics than recommended on the product label may cause:
Gas
Stomach cramps
Loose or more frequent stools
These symptoms are usually mild and should improve after you lower the dose or stop taking the probiotic.
Probiotics may cause temporary digestive symptoms (like gas, bloating, and stomach cramps). These symptoms are usually mild and improve as your body adjusts. Rarely, probiotics can cause infections, especially in people with a weakened immune system.
Taking more probiotics than recommended on the product label may cause:
Gas
Stomach cramps
Loose or more frequent stools
These symptoms are usually mild and should improve after you lower the dose or stop taking the probiotic.
Probiotics may cause temporary digestive symptoms (like gas, bloating, and stomach cramps). These symptoms are usually mild and improve as your body adjusts. Rarely, probiotics can cause infections, especially in people with a weakened immune system.
High doses of vitamin C can cause diarrhea, nausea, and stomach cramps. Some multivitamins may also cause diarrhea because they contain magnesium, a mineral that can have a laxative effect. Check the supplement label and avoid taking more than the recommended dose.
The bottom line
Probiotics can sometimes cause temporary diarrhea, especially when you first start taking them. They may also cause gas, bloating, or stomach cramps while your digestive system adjusts. These symptoms are usually mild and improve with time. Follow the product instructions, and stop taking the probiotic if your symptoms are severe or don’t improve.
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References
Blaabjerg, S., et al. (2017). Probiotics for the prevention of antibiotic-associated diarrhea in outpatients—A systematic review and meta-analysis. Antibiotics.
Center for Ecogenetics and Environmental Health. (2014). Fast facts about the human microbiome. University of Washington.
Ciorba, M. A. (2012). A gastroenterologist's guide to probiotics. Clinical Gastroenterology and Hepatology.
Goldenberg, J. Z., et al. (2017). Probiotics for the prevention of Clostridium difficile‐associated diarrhea in adults and children. Cochrane Database of Systematic Reviews.
Katkowska, M., et al. (2021). Probiotics: Should all patients take them? Microorganisms.
Kechagia, M., et al. (2013). Health benefits of probiotics: A review. International Scholarly Research Notices Nutrition.
Kwoji, I. D., et al. (2021). Multi-strain probiotics: Synergy among isolates enhances biological activities. Biology.
McFarland, L. V. (2020). Efficacy of single-strain probiotics versus multi-strain mixtures: Systematic review of strain and disease specificity. Digestive Diseases and Sciences.
Mitelmão, F. C. R., et al. (2022). The effect of probiotics on functional constipation in adults: A randomized, double-blind controlled trial. Medicine.
National Center for Complementary and Integrative Health. (2019). Probiotics: What you need to know.
Office of Dietary Supplements. (2021). Vitamin C. National Institutes of Health.
Office of Dietary Supplements. (2025). Probiotics. National Institutes of Health.
Ouwehand, A. C., et al. (2018). Effectiveness of multi-strain versus single-strain probiotics: Current status and recommendations for the future. Journal of Clinical Gastroenterology.
Sarita, B., et al. (2025). A comprehensive review of probiotics and human health-current prospective and applications. Frontiers.
