Overview

  • What are Probiotics?

    The World Health Organization says that probiotics are "live microorganisms which when administered in adequate amounts confer [give] health benefits on the host [person or living thing taking it in]."

    • Bacteria, viruses and yeast are all types of “microorganisms”. These are often called germs or bugs – different bugs than the creepy, crawly kind!
    • Good bugs live in your gut without making you sick. These bugs help you be healthy.
    • Sometimes there are too many bad bugs in the gut. This can make you sick.
    • Probiotic pills and some foods (like yogurt) have good bugs that may be helpful.
  • How do Probiotics Work?

    We don’t really know. They may make it harder for bad bugs to live in your gut. Bad gut bugs can give you more gas, belly swelling (bloating), or diarrhea. Some good gut bugs help the immune system fight infection. Other good gut bugs help keep the bad ones from going to the rest of your body.

  • Are All Probiotics the Same?

    There are A LOT of different probiotic pills – it can be overwhelming! Some have many types of good bugs (“strains”) and some have only one kind. Some have higher doses of these bugs (CFUs or “colony forming units”) than others. As of right now, we do not know if one type or dose is better than another.

  • How do I Know What Type Will Make Me Feel Better?

    Start by talking to your primary care provider or gastroenterologist.

    Scientific studies have not been done on many probiotics. The Food and Drug Administration (FDA) does not regulate probiotics. This means we do not know if probiotics are helpful or safe for certain symptoms or illnesses.

    Some probiotics have been scientifically studied in people with gastrointestinal problems. Some studies found the probiotics helpful. Other studies could not say for sure. We need more scientific studies.

    It is helpful to look at the science for each gastrointestinal condition individually. Probiotics may be helpful for the following conditions:

    Irritable Bowel Syndrome (IBS): Probiotics have been tested the most for IBS. Some probiotics seem to help people with IBS and others do not seem to help. The bugs that seem to help the most are called Bifidobacterium and Lactobacillus. However, not all experts recommend probiotics for IBS because the scientific evidence is limited. Your provider may be able to help guide you.

    Antibiotic Associated Diarrhea (AAD): Antibiotic Associated Diarrhea (AAD): A lot of scientific evidence shows that probiotics help prevent and lessen diarrhea from antibiotics.

    • Take the probiotic while you are taking the antibiotic, but at a different time of day.
      • For example, if you are taking an antibiotic in the morning and evening, take the probiotic in the middle of the day.
      • It seems Saccharomyces boulardii (S. boulardii), a yeast, and Lactobacillus rhamnosus GG are the most helpful bugs.
    • Infectious Diarrhea: Scientific studies have shown that good bugs can help diarrhea caused by bad bugs. We do not know what types of good bugs help the most though.
    • Clostridium difficile Associated Diarrhea (CDAD): Scientific studies have not found probiotics helpful in fighting diarrhea from this infection. Experts disagree about whether probiotics are helpful in preventing this infection.
    • Inflammatory Bowel Disease (IBD): Some scientific studies found probiotics may help some types of IBD.
      • Crohn's Disease (CD): Probiotics do not seem to help people with Crohn’s.
      • Ulcerative Colitis (UC): Two probiotics called Visbiome (formerly VSL #3) and E. Coli Nissle 1917 may help people with Ulcerative Colitis.
    • Pouchitis: What exactly is Pouchitis?
      • Some people with ulcerative colitis get their colon taken out.
      • Surgeons use the small intestine to make a new pocket (a “pouch”) for the poop. Poop sits in this pouch before it is passed from the body.
      • An inflamed pouch is red, swollen or has sores/ulcers on the inside (“pouchitis”)
      • Pouchitis causes people to poop more often and urgently, sometimes with blood or mucus.
      • About 2 to 5 people out of 10 people with a pouch will get pouchitis in the first year after surgery.
      • Pouchitis is treated with antibiotics. However, it can come back a lot.
      • A few scientific studies show that the probiotic called Visbiome (formerly VSL#3) taken soon after surgery can help prevent pouchitis. Not all experts recommend this because there is only a small amount of science.
  • How Long Should I Continue Taking My Probiotic if it Works?

    We do not know how long it is OK to take probiotics. Talk with your provider about whether to keep taking them or not.

  • Are Probiotics Safe?

    We think that probiotics are safe for most people. People have been using probiotics for more than 100 years without much trouble. However, the Food and Drug Administration (FDA) does not check probiotics to see if they are safe. Therefore, it is good to be careful when taking them.

    Probiotics may be dangerous for people with certain health problems. People with serious or chronic health conditions should definitely speak to their provider before taking probiotics.

  • Are Probiotics the Same as Prebiotics?

    No. Prebiotics are the stuff in food or pills that makes YOUR OWN good bugs grow (instead of GIVING YOU more good bugs). Your body cannot break down prebiotics. Prebiotics are left as food for the good bugs in your bowels.

Author(s) and Publication Date(s)

Darren M. Brenner, MD, Northwestern University, Feinberg School of Medicine, Chicago, IL – Published July 2011.

Chien-Huan Chen, MD, PhD, Washington University School of Medicine, St. Louis, MO – Updated 2020.

Lauren Tormey, Dartmouth-Hitchcock Medical Center, Lebanon, NH – Updated July 2022.

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