Overview

Probiotics are live bacteria and yeasts that are thought to improve health. The most common are lactobacilli, bifidobacteria, and Saccharomyces boulardii.

Many bacteria and other organisms live in our bodies normally. These "good" bacteria and yeasts can help break down food, absorb nutrients, and fight off "bad" organisms that might cause diseases. Probiotics are sometimes taken as supplements and are also found in foods such as yogurt.

Probiotics are used for many different types of diarrhea, irritable bowel syndrome (IBS), constipation, and many other conditions. Keep in mind that not all probiotics have the same effects. One probiotic or combination of probiotics may be helpful for certain conditions, while other probiotics are not. Also, there is no good evidence to support using any probiotics for COVID-19.

Uses & Effectiveness

Possibly Effective for

  • Stomach pain. Taking a specific probiotic called L. reuteri by mouth seems to reduce stomach pain in children. It's not clear if other probiotic species help.
  • Diarrhea in people taking antibiotics (antibiotic-associated diarrhea). Taking probiotics by mouth, especially S. boulardii, B. subtilis, and some lactobacilli and bifidobacteria, seems to reduce the risk of getting diarrhea from antibiotics in both adults and children.
  • Eczema (atopic dermatitis). Taking probiotics by mouth, especially lactobacilli, seems to help prevent eczema in children. But it doesn't seem to help treat eczema.
  • Prone to allergies and allergic reactions (atopic disease). Taking a specific probiotic strain (L. rhamnosus GG; Culturelle) by mouth seems to help prevent allergic reactions in babies. Other probiotic products don't seem to work as well.
  • Overgrowth of bacteria in the vagina. Taking probiotics by mouth or applying to the vagina, either alone or with antibiotics, seems to help treat this condition.
  • Infection of the gastrointestinal tract by a bacteria called Clostridium difficile. Taking probiotics by mouth might reduce the chance of developing this infection for the first time in some high-risk people. Taking S. boulardii probiotics by mouth might reduce the chance of getting this infection again in certain people who've already had it. But it's not clear if taking any other probiotics can reduce the chance of getting this infection again.
  • Excessive crying in infants (colic). Giving infants L. reuteri DSM 17938 or B. animalis subsp. lactis BB-12 by mouth seems to decrease crying time in babies with colic. But probiotics don't seem to prevent colic.
  • Constipation. Taking probiotics by mouth seems to help adults with constipation, but not children.
  • Diarrhea. Probiotics seem to help prevent and treat diarrhea due to a variety of causes in adults and children.
  • A digestive tract infection that can lead to ulcers (Helicobacter pylori or H. pylori). Taking probiotics by mouth along with the standard medications for H. pylori infection can improve how well the treatment works in some people.
  • Reduced brain function in people with advanced liver disease (hepatic encephalopathy). Taking probiotics by mouth can improve brain function in people with advanced liver disease.
  • High cholesterol. Taking probiotics, especially L. plantarum and L. reuteri, by mouth seems to help lower cholesterol in some people with high cholesterol.
  • A long-term disorder of the large intestines that causes stomach pain (irritable bowel syndrome or IBS). Taking probiotics by mouth seems to improve symptoms such as stomach pain and bloating in people with IBS.
  • Liver transplant. Taking probiotics by mouth seems to improve recovery and reduce infections following a liver transplant.
  • A serious intestinal disease in premature infants (necrotizing enterocolitis or NEC). Giving products containing multiple probiotics by mouth to preterm infants seems to reduce the chance of developing this condition. However, it isn't clear which probiotic or group of probiotics might work best. Also, some probiotics have caused blood infections in very small premature infants.
  • Ear infection (otitis media). Taking a probiotic by mouth seems to help prevent ear infections in children.
  • A complication after surgery for ulcerative colitis (pouchitis). Taking products containing multiple probiotics by mouth seems to help treat pouchitis in some people.
  • A complication after surgery for ulcerative colitis (pouchitis). Taking products containing multiple probiotics by mouth seems to help treat pouchitis in some people.
  • Diarrhea caused by radiation therapy. Taking probiotics by mouth seems to help prevent diarrhea caused by radiation therapy.
  • Infection of the airways. Taking probiotics by mouth might reduce the chance of developing an airway infection in children and adults. It isn't clear which probiotic might work best.
  • Diarrhea caused by rotavirus. Taking S. boulardii probiotics by mouth can reduce the length of diarrhea in children with rotaviral diarrhea. It's not clear if other probiotics help.
  • Ulcerative colitis. Taking products containing multiple probiotics by mouth seems to help reduce symptoms of ulcerative colitis in some people.

Possibly Ineffective for

  • Decline in memory and thinking skills that occurs normally with age. Taking probiotics containing B. breve by mouth does not seem to improve thinking and memory skills in older adults. It's not clear if other probiotics might help.
  • A type of inflammatory bowel disease (Crohn disease). Taking probiotics by mouth doesn't increase the chance of remission from Crohn disease. It also doesn't decrease the chance of relapse for people who are already in remission.
  • Airway infections caused by exercise. Taking probiotics by mouth, especially lactobacilli, doesn't reduce the risk of developing an airway infection after exercise.
  • Blood infection (sepsis). Taking probiotics by mouth doesn't seem to reduce the chance of sepsis in premature babies.
  • Vaginal yeast infections. Taking probiotics by mouth or using vaginal suppositories doesn't help treat or prevent vaginal yeast infections.

There is interest in using probiotics for a number of other purposes, but there isn't enough reliable information to say whether it might be helpful.

Side Effects

When taken by mouth: Commonly used probiotic species seem to be safe for most adults. Some of the most well-studied species include L. acidophilus, L. casei, L. paracasei, L. plantarum, L. reuteri, L. rhamnosus, B. bifidum, B. breve, B. lactis, B. longum, S. thermophilus, and/or S. boulardii. Side effects are usually mild and most often include gas or bloating. There isn't enough reliable information about the safety of other probiotic species.

When inserted into the vagina: Probiotics containing L. acidophilus, L. plantarum, and L. rhamnosus are likely safe when used short-term. There isn't enough reliable information to know if other probiotic species are safe.

Special Precautions and Warnings

When taken by mouth: Commonly used probiotic species seem to be safe for most adults. Some of the most well-studied species include L. acidophilus, L. casei, L. paracasei, L. plantarum, L. reuteri, L. rhamnosus, B. bifidum, B. breve, B. lactis, B. longum, S. thermophilus, and/or S. boulardii. Side effects are usually mild and most often include gas or bloating. There isn't enough reliable information about the safety of other probiotic species.

When inserted into the vagina: Probiotics containing L. acidophilus, L. plantarum, and L. rhamnosus are likely safe when used short-term. There isn't enough reliable information to know if other probiotic species are safe.

Pregnancy and breast-feeding: It is possibly safe to take probiotic products containing L. acidophilus, L. casei, L. fermentum, L. paracasei, L. plantarum, L. reuteri, L. rhamnosus, L. salivarius, B. bifidum, and/or B. longum by mouth while pregnant or breast-feeding. There isn't enough reliable information to know if other probiotic species are safe to use when pregnant or breast-feeding. Stay on the safe side and avoid use.

Children: It is likely safe for children to take probiotic products containing L. acidophilus, L. casei, L. paracasei, L. plantarum, L. reuteri, L. rhamnosus, B. bifidum, B. breve, B. lactis, and/or B. longum. It is possibly safe for children to take probiotic products containing B. coagulans, L. gasseri, L. helveticus, L. johnsonii, L. brevis, L. salivarius, L. fermentum, S. boulardii, and/or S. thermophilus. There isn't enough reliable information to know if other probiotic species are safe for children or if probiotics are safe for very small premature infants.

Central lines: Infections of the blood have been reported in people who have central lines and take probiotics, especially S. boulardii. In many cases, infections were caused when the catheter became contaminated. If you have a central line, talk with your healthcare provider before taking probiotics.

Digestive system problems: Infections of the blood have been reported in a small number of people with digestive system conditions such as short bowel syndrome, ulcerative colitis, or intestinal obstruction (after abdominal surgery) who were taking probiotics. If you have any of these conditions, talk with your healthcare provider before taking probiotics.

Weakened immune system: Probiotics have caused blood infections in a small number of people with weakened immune systems. If you have a weakened immune system, talk with your healthcare provider before taking probiotics.

Damaged heart valves: Probiotic preparations containing lactobacilli can cause an infection in the inner lining of the heart chambers and heart valve. This is extremely rare, but people with damaged heart valves should stop taking probiotics before dental procedures or surgical procedures.

Yeast allergy: People with yeast allergy can be allergic to probiotic products containing S. boulardii and should avoid these products if possible.

Interactions

    Minor Interaction

    Be watchful with this combination

  • Antibiotic drugs interacts with Probiotics

    Most probiotics are friendly bacteria. Antibiotics are used to reduce harmful bacteria in the body. Taking antibiotics along with these probiotics can reduce the effects of the probiotics. To avoid this interaction, take probiotic products at least 2 hours before or after antibiotics.

  • Medications for fungal infections (Antifungals) interacts with Probiotics

    Some probiotics are friendly yeasts (fungi). Medications for fungal infections help reduce fungus in and on the body. Taking antifungals along with probiotics that are yeasts can reduce the effects of these probiotics.

Dosing

Probiotics are commonly taken in dietary supplements and foods, such as yogurt. The most common probiotics found in these products include various types of lactobacilli, bifidobacteria, and Saccharomyces boulardii. But many other bacteria and yeast species can be found in probiotic products.

The strength of bacterial probiotics is usually given as the number of living organisms, or colony-forming units (CFU), per capsule. The strength of fungal probiotics may be given in micrograms or milligrams. To learn more about how specific probiotics are typically used, review our monographs on those topics.
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