Lactobacillus reuteri (L. reuteri) is a common probiotic bacterium naturally found in the human gut, often used to support digestive health or manage infant colic. Introducing any supplement containing live organisms can lead to a period of adjustment and potential side effects. Understanding the safety profile and adverse reactions of this probiotic is important for consumers. This discussion details the common, mild digestive changes, explains when to discontinue the supplement, and outlines rare but serious health risks and populations requiring medical supervision.
Expected Digestive Adjustments
The most frequently reported side effects of starting an L. reuteri supplement are related to the digestive tract and are typically mild and temporary. As the new bacteria colonize and interact with the existing gut microbiota, individuals may experience increased gas, known as flatulence, or temporary abdominal discomfort. This transient discomfort often includes bloating, a sensation of fullness or swelling in the abdomen. Minor changes in bowel movements are also common, sometimes manifesting as looser stools or mild diarrhea. For most people, these effects are dose-dependent and subside naturally within the first few days or weeks of consistent use.
When to Stop Taking the Probiotic
Managing these common digestive adjustments often involves simple strategies to help the body acclimate to the supplement. If symptoms like mild bloating or gas are bothersome, reducing the daily dosage can lessen the initial impact of the new bacteria. Taking the probiotic alongside a meal instead of on an empty stomach may also help improve tolerance and reduce gastrointestinal upset. If the mild digestive symptoms persist intensely for longer than two weeks, or if they significantly worsen, discontinue the product and consult a healthcare provider. Discontinuation is also warranted if any new, severe abdominal pain develops that is clearly distinct from minor discomfort.
Serious Health Risks and Rare Reactions
While L. reuteri is generally well-tolerated, rare but severe adverse events are possible, often involving a systemic reaction. The most serious risk is systemic infection, such as bacteremia, where the probiotic bacteria enter the bloodstream. This translocation from the gut to the circulatory system is extremely uncommon in healthy individuals. Symptoms of a systemic infection include persistent fever, chills, and a sore throat that does not resolve. Another rare but serious reaction is a severe allergic response, which can present as hives, swelling of the face or tongue, or difficulty breathing (anaphylaxis). Any sign of a severe allergic reaction or systemic infection requires immediate medical attention and complete cessation of the probiotic.
Populations Requiring Caution
Certain individuals face a significantly higher risk profile for complications from L. reuteri and should only use it under strict medical supervision. People who are severely immunocompromised, such as those undergoing chemotherapy or individuals with HIV/AIDS, are particularly vulnerable to probiotic-induced infections like bacteremia. The weakened immune system cannot effectively contain the live bacteria, which increases the chance of translocation into the bloodstream. Patients with damaged heart valves or those scheduled for surgical procedures are also advised to exercise caution, as there is a rare risk of the bacteria causing an infection in the heart’s inner lining. Furthermore, premature infants are considered a high-risk group due to their underdeveloped gut barriers and immune systems. Individuals with Short Bowel Syndrome or other severe gastrointestinal conditions also need medical guidance.