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Probiotics are often used as a treatment for irritable bowel syndrome (IBS).1 Probiotics, also called “good bacteria,” are defined as live microorganisms that are similar to the beneficial bacteria found in the human gut.2 Although the exact cause of IBS is unknown, it is thought to be a combination of factors, with alterations in the muscle movements of the gut, bacterial overgrowth, hypersensitivity, and microscopic inflammation potentially contributing to the condition.4 Probiotics are believed to help restore the gut environment in delivering beneficial bacteria into the gut.1

Although bacteria are often considered as harmful “germs,” there are in fact a number of bacteria that naturally live in the human digestive tract and work in cooperation with the human body, helping it to function properly. Probiotics are the same or similar to these helpful bacteria.3

Research on Probiotics in the Treatment of IBS

The most well-studied probiotic is Bifidobacteria infantis, which has been proven to reduce the abdominal symptoms of IBS, particularly bloating and bowel function. Other studies have looked at strains of the Lactobacillus and Propionibacterium species.4 In addition, a recent analysis of the research that included multiple probiotics, many administered in combinations, found evidence to support that probiotics benefit IBS patients, but there is no consensus or recommendations on what the optimal strains, combinations or doses are for patients with IBS.1

Although their exact action is unknown, probiotics are believed to help IBS by improving the mucosal lining and restoring the gut’s barrier function.1 Probiotics suppress the growth and binding of destructive bacteria in the gut, and they alter the acidity level in the intestines and improve the immune response.4

There is some evidence that various probiotics are helpful in preventing diarrhea and improving symptoms of IBS, but there is no conclusive evidence to determine which probiotics are helpful and which are not. It is also unknown how much of the probiotic patients need to take or which patients would most benefit from taking probiotics.

Sources of Probiotics

Probiotics are available in several formulations. Oral products, including dietary supplements and yogurts, are available at many grocery stores, health food stores and pharmacies. Other products that deliver probiotics include suppositories and creams.3 It is worth noting that because probiotics are not considered pharmaceutical drugs, they are not currently regulated by the U. S. Food and Drug Administration, and there may be substantial differences in the quality and effectiveness of various brands.3,4 Patients are encouraged to talk to their doctor or pharmacist about recommended brands of probiotics.

When Considering Probiotics

Studies have shown that probiotics usually have few side effects, however the long-term safety data is limited. In healthy people, probiotics have minor side effects, if any. However, in people with other health conditions, such as weakened immune systems, there have been occasional serious complications reported, such as infections.3

Every person reacts differently to different treatments, including probiotics, medications, complementary and dietary changes. Discussing all possible treatment options with a health care professional is recommended.

Other Treatment Options

The management of IBS symptoms is usually accomplished by a combination of approaches, and determining the best combination for a patient may require some trial and error. Besides probiotics, other treatment strategies include adding exercise, making dietary changes, adding fiber, using medication, or trying complementary or alternative medicine.

Written by: Emily Downward | Last reviewed: July 2019
  1. Lacy BE, Chey WD, Lembo AJ. New and emerging treatment options for irritable bowel syndrome. Gastroenterol Hepatol (N Y). 2015;11(4 Suppl 2):1-19.
  2. National Center for Complementary and Alternative Medicine. An Introduction to Probiotics. Accessed online on 3/3/16 at
  3. National Center for Complementary and Integrative Health. Probiotics: in depth. Accessed online on 3/7/16 at
  4. Aragon G, Graham DB, Borum M, Doman DB. Probiotic therapy for irritable bowel syndrome. Gastroenterol Hepatol (N Y). 2010 Jan;6(1):39-44.