Background

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.

Safety Safety definitions

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 & Warnings:

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.

Effectiveness

Dosing & administration

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.

Interactions with pharmaceuticals

Antibiotic drugs

Interaction Rating=Moderate Be cautious with this combination.

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)

Interaction Rating=Minor Be watchful with this combination.

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.

Interactions with herbs & supplements

There are no known interactions with herbs and supplements.

Interactions with foods

There are no known interactions with foods.