Reviews Overview: Levilactobacillus brevis (L. brevis) is a probiotic bacteria that is available over the counter as a supplement and in some fermented foods. It is commonly used to improve mouth and gut health, but its benefits are not well defined. Common side effects include gas and an upset stomach. Serious side effects are rare but include infections in some people who are at high risk for infections. Before using L. brevis, make sure to tell your health care provider about any health conditions you have or medicines you are taking.
Uses
What is Levilactobacillus brevis (L. brevis) used for?
L. brevis is a probiotic that is commonly used to improve mouth and gut health, but its benefits are not well defined.
L. brevis is available as a dietary supplement in various strengths and dosage forms. Some dietary supplements that contain L. brevis also contain many other ingredients, including other probiotics.
Note: The FDA has not reviewed L. brevis for safety and effectiveness. Learn more about dietary supplements here.
How does L. brevis work (mechanism of action)?
L. brevis is a species of bacteria. It is a type of probiotic, which means it is a live microbe that may provide health benefits in some people.
Your gut and mouth are home to millions of different microbes, which make up part of your microbiome. L. brevis is naturally found in your gut. You can also get L. brevis from dietary supplements and some fermented foods, including certain vegetables and dairy products.
L. brevis makes a substance called lactic acid. Lactic acid can help improve the health of your microbiome by reducing the amount of bad bacteria and increasing the amount of good bacteria. When the microbiome in your gut is healthy, it can make you more able to digest foods and resist infections. When the microbiome in your mouth is healthy, you may be more able to resist dental cavities. Sucking on lozenges that contain L. brevis may also help increase the pH in your mouth. This may help fight off cavities and protect the enamel on your teeth. But the benefits of L. brevis for any use are not well defined.
Taking L. brevis by mouth increases the levels of this bacteria in your mouth or gut. This may help improve the health of your microbiome. But there are many factors that can affect whether a probiotic survives in your body. When you take L. brevis by mouth, it may not always survive long enough to grow and multiply in your mouth or gut. As a result, its benefits are not well defined and may be different for each person.
How should I store L. brevis?
You should store L. brevis according to the product label. Most dietary supplements should be kept in a cool, dry location that is out of the reach of children and pets and not in direct sunlight.
Side Effects
What are the most common side effects of L. brevis?
The most common side effects of L. brevis are listed below. These side effects may vary depending on the dose you are taking or the specific product you are using. Tell your health care provider if you have any of these side effects that bother you.
- Gas
- Upset stomach
There may be other side effects of L. brevis that are not listed here. Contact your health care provider if you think you are having a side effect of a supplement. In the U.S., you can report side effects to the FDA at www.safetyreporting.hhs.gov or by calling 888-SAFEFOOD (888-723-3366). In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.
What are the serious side effects of L. brevis?
While less common, the most serious side effects of L. brevis are described below, along with what to do if they happen.
Severe Allergic Reactions. L. brevis may cause allergic reactions, which can be serious. Stop using L. brevis and get help right away if you have any of the following symptoms of a serious allergic reaction.
- Breathing problems or wheezing
- Racing heart
- Fever or general ill feeling
- Swollen lymph nodes
- Swelling of the face, lips, mouth, tongue, or throat
- Trouble swallowing or throat tightness
- Itching or skin rash
- Bumps on the skin called hives that can be red, pink, white, or brown depending on your skin tone
- Nausea or vomiting
- Dizziness, feeling lightheaded, or fainting
- Stomach cramps
- Joint pain
Serious Infections. In very rare cases, some people who use probiotics, such as L. brevis, can get a serious infection. This happens when L. brevis moves into a part of the body where it is not supposed to be, such as your blood. This is most likely to happen in people who are very sick or who have very weak immune systems, such as people with cancer or who are receiving chemotherapy. Call your health care provider right away if you have any of the following symptoms.
- Fever, sweats, chills, or muscle aches
- Tiredness
- Shortness of breath
- Fast heartbeat
Warnings & Precautions
Who should not use L. brevis?
Allergies to Ingredients. People who are allergic to any of the following should not use L. brevis.
- L. brevis
- Lactobacillus brevis
- Levilactobacillus brevis
- Any of the ingredients in the specific product
Your pharmacist can tell you all of the ingredients in the specific L. brevis products they stock.
What should I know about L. brevis before using it?
L. brevis is a dietary supplement. It cannot be marketed to treat or cure a disease.
Read and follow the directions on the specific product you are using, or use it as recommended by your health care provider.
Keep L. brevis out of the reach of children.
Premature infants can be at greater risk of having side effects from probiotics, such as L. brevis. Talk to your health care provider about the risks if your infant was born prematurely.
The full name of L. brevis, Levilactobacillus brevis, has only been around since 2020. Before then, this species of bacteria was called Lactobacillus brevis. You may still see both of these names on product labels. These are the same species of bacteria.
L. brevis may be available as a lozenge, tablet, or capsule. Lozenges are similar to cough drops and are meant to be sucked on. Do not chew L. brevis lozenges or swallow them whole. If you have a cut or an open sore in your mouth, speak with a health care provider before using L. brevis lozenges.
Probiotics, such as L. brevis, are usually measured in colony forming units (CFUs). Each CFU is equal to one living bacteria. The number of CFUs listed on the product label tells you how many living bacteria should be in that product on the day that it expires. Since bacteria slowly die off over time, the number of living bacteria in the product may be higher than the amount on the label.
Many probiotic products contain multiple species of microbes. Different microbes can have different effects in the body. It is important to read the product label closely to understand which species of bacteria are in that product.
L. brevis is a species of bacteria. Within that species are many different strains. Each strain of L. brevis may have slightly different effects in the body. This means that some strains of L. brevis may have certain effects that other strains do not have. If the product you are using contains a specific strain, it should be listed on the product label as the string of numbers or letters that come after “L. brevis.” If you switch to a different strain of L. brevis, it may not have the same effects or side effects. Talk to your health care provider if you have questions or concerns.
Some probiotic products have been found to contain other microbes that are not listed on the label and that may cause serious health problems. The FDA has not tested L. brevis products to confirm that they contain the ingredients stated on their labels. Some dietary supplements have been tested by third-party organizations to confirm that they contain the ingredients listed on their labels and do not contain any harmful chemicals. Learn more about how to choose a safe dietary supplement product here.
What should I tell my health care provider before using L. brevis?
Tell your health care provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them know if L. brevis is right for you.
In particular, make sure that you discuss any of the following.
Central Line or Port. A central venous catheter (central line) or port is a small tube placed into a vein that can be used to give medicines and fluids directly into the vein (intravenously, or IV). These tubes can become infected by microbes, including probiotics. If you have a central line or port, speak with your health care provider before using L. brevis.
Other Current and Past Health Conditions. Tell your health care provider if you have any of the following.
- A serious infection in the mouth or an infection in the mouth that keeps coming back
- Cuts or open sores in the mouth
- An autoimmune condition
- Cancer
- Immune problems, such as a weak immune system
Other Medicines and Supplements. L. brevis may interact with other medicines and supplements. Before using L. brevis, tell your health care provider about any prescription or OTC medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section for more details.
Pregnancy. It is not known if or how L. brevis could affect pregnancy or harm a fetus. Tell your health care provider if you are pregnant or plan to become pregnant.
Breastfeeding. It is not known if L. brevis passes into breast milk. Tell your health care provider if you are breastfeeding or plan to breastfeed.
Interactions
Does L. brevis interact with foods or drinks?
There are no known interactions between L. brevis and foods or drinks.
It is unknown if drinking alcohol will affect L. brevis.
Does L. brevis interact with medicines (drug interactions)?
Always tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.
In particular, make sure that you discuss if you are using any of the following before using L. brevis.
- A medicine that suppresses the immune system
- An antibiotic, which is used to treat certain bacterial infections
- Chemotherapy, which is used to treat certain cancers
The interactions between L. brevis and medicines are not fully understood. As with most dietary supplements, the research on drug interactions with L. brevis is incomplete. Always check with your health care provider before using L. brevis with any medicines.
Overdose/Missed Dose
What should I do if I accidentally use too much L. brevis?
If you or someone else has used too much L. brevis, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.
L. brevis products may contain many ingredients, including other probiotics. Read the product label closely, and speak with a health care provider about how to use L. brevis safely. Do not use double or extra doses, even if you miss a dose.
Clinical Oral Investigations: “Effect of a daily dose of Lactobacillus brevis CD2 lozenges in high caries risk schoolchildren,” “Effect of Lactobacillus brevis CD2 containing lozenges and plaque pH and cariogenic bacteria in diabetic children: A randomised clinical trial.”
Journal of Translational Medicine: “Levilactobacillus brevis CD2 as a multifaceted probiotic to preserve oral health: results of a double-blind, randomized, placebo-controlled trial in healthy adults.”
International Journal of Food Sciences and Nutrition: “Effect of combined consumption of Lactobacillus brevis KB290 and β-carotene on minor diarrhoea-predominant irritable bowel syndrome-like symptoms in healthy subjects: A randomised, double-blind, placebo-controlled, parallel-group trial.”
National Center for Complementary and Integrative Health: “5 Things To Know About Probiotics,” “Probiotics: Usefulness and Safety.”
National Institutes of Health Office of Dietary Supplements: “Probiotics Fact Sheet for Consumers,” “Probiotics Fact Sheet for Health Professionals.”
FDA: “FDA Raises Concerns About Probiotic Products Sold for Use in Hospitalized Preterm Infants.”
Clinical Oral Investigations: “Effect of a daily dose of Lactobacillus brevis CD2 lozenges in high caries risk schoolchildren,” “Effect of Lactobacillus brevis CD2 containing lozenges and plaque pH and cariogenic bacteria in diabetic children: A randomised clinical trial.”
Journal of Translational Medicine: “Levilactobacillus brevis CD2 as a multifaceted probiotic to preserve oral health: results of a double-blind, randomized, placebo-controlled trial in healthy adults.”
International Journal of Food Sciences and Nutrition: “Effect of combined consumption of Lactobacillus brevis KB290 and β-carotene on minor diarrhoea-predominant irritable bowel syndrome-like symptoms in healthy subjects: A randomised, double-blind, placebo-controlled, parallel-group trial.”
National Center for Complementary and Integrative Health: “5 Things To Know About Probiotics,” “Probiotics: Usefulness and Safety.”
National Institutes of Health Office of Dietary Supplements: “Probiotics Fact Sheet for Consumers,” “Probiotics Fact Sheet for Health Professionals.”
FDA: “FDA Raises Concerns About Probiotic Products Sold for Use in Hospitalized Preterm Infants.”