Lactobacillus rhamnosus GG, usually shortened to LGG, is one of the most widely used probiotic strains, according to a 2014 review of its host interactions. Its best-supported use is in diarrhea: a 2022 descriptive review of probiotics in pediatrics says LGG and Saccharomyces boulardii “may shorten their duration and symptoms” in acute diarrhea and antibiotic-associated diarrhea. The same 2014 review notes that not all intervention studies showed a clinical benefit, and that results for the same condition are not always the same.
What is Lactobacillus rhamnosus GG?
LGG is one strain of Lactobacillus rhamnosus, a bacterium that lives in the gut. The Thirty Years of Lactobacillus rhamnosus GG review says LGG was the first strain of its genus to be patented, in 1989, because it survives at gastric acid pH and in bile, and adheres to intestinal cells. It also says the strain produces a biofilm that can mechanically protect the gut lining.
BioPhysics Essentials, which sells its own multi-strain probiotic, says in its Gut Check blog that the species was renamed Lacticaseibacillus rhamnosus in 2020 and that both names refer to the same organism. You may see either name on a label.
For the basics of the gut microbiome, Harvard Health gut health article describes it as all the microorganisms, both good and bad, living in your gastrointestinal tract, mainly the large intestine.
What is LGG used for, and what do studies show?
The table below reports each use the way its source states it. Figures come from the BioPhysics Essentials Gut Check blog, which cites the trials it describes, and from the review named in each row.
| Use | What the research reports | Where it is reported |
|---|---|---|
| Antibiotic-associated diarrhea | In a 2015 meta-analysis of 12 randomized trials with 1,499 participants, the rate went from 22.4% to 12.3% compared with placebo or no added treatment | Gut Check blog, citing the 2015 meta-analysis by Szajewska and Kołodziej |
| Acute diarrhea in children | LGG and Saccharomyces boulardii “may shorten their duration and symptoms” | 2022 pediatric review |
| Acute gastroenteritis in children | A 2018 trial found no significant difference between LGG and placebo for children presenting to North American emergency departments | Gut Check blog, citing a 2018 trial in the New England Journal of Medicine |
| Infant colic | LGG and L. reuteri DSM 17938 “were effective to manage infant colic” | 2022 pediatric review |
| Eczema (atopic dermatitis) | Giving LGG during pregnancy “reduced its development in the infant” | 2022 pediatric review |
| Cow’s milk protein allergy | Use of the strain in infant formula “may promote an earlier tolerance acquisition” | 2022 pediatric review |
| Other areas | Gastrointestinal infections, irritable bowel syndrome, inflammatory bowel disease, respiratory infections, allergy, cardiovascular disease, fatty liver, cancer and sport | Thirty Years of Lactobacillus rhamnosus GG, which analysed these areas |
Why do LGG study results differ from one trial to the next?
Three things come up across the sources. First, the 2014 review says a person’s age, genetics and gut microbes help decide whether they respond to a probiotic. Second, the Gut Check blog says European studies have generally shown more positive results for children with acute gastroenteritis than North American ones, and proposes that differences in baseline gut microbes may explain it. Third, results depend on the strain. The blog stresses that strain-specific effects are critical.
A 2025 trial of yogurt in overweight or obese adults compared an Akkermansia postbiotic yogurt with a yogurt containing a Lactobacillus rhamnosus postbiotic over eight weeks, in 66 people. The trial reports that the Akkermansia yogurt showed benefits on several measures, while the Lactobacillus rhamnosus-fortified yogurt “did not demonstrate any beneficial impact on the health parameters.” That trial does not name GG as the strain.
Does Lactobacillus rhamnosus help with anxiety?
The anxiety research mostly uses a different strain, JB-1, not LGG. The Gut Check blog reports that a 2011 study in mice found JB-1 reduced anxiety-related behaviour, and that the effect depended on an intact vagus nerve. In a 2017 randomized trial in healthy young men, four weeks of JB-1 did not significantly change stress responses, anxiety or cognitive performance, according to the same blog. The blog also reports a 2025 rat study in which LGG showed antidepressant properties. That is an animal finding, not a human one.
Product pages often describe mood benefits more broadly. Those are the seller’s own statements, not findings from trials.
Can I take probiotics if I have colitis?
The 2019 review lists inflammatory bowel disease among the areas it analysed for LGG. Its abstract gives that list rather than a single finding, so read the full paper if this is your question. Colitis is a diagnosis that needs a plan from your own clinician. Your gastroenterologist can tell you whether a probiotic fits your type of colitis and your current medicines.
The Gut Check blog lists people who should check with a clinician first: immunocompromised people, people with central venous catheters, people with severe acute pancreatitis, and premature infants.
Should I take probiotics with minocycline, and what should I avoid?
This page is about LGG and does not cover minocycline. It does not answer whether to take a probiotic with minocycline, whether dairy matters, what time of day to take it, what to avoid, or how risky minocycline is. The same applies to which antibiotics are hardest on the gut microbiome.
Ask the pharmacist who fills your prescription or the prescriber who wrote it. Bring the name of any probiotic you are considering and ask whether it should be spaced from your minocycline.
What are Culturelle probiotics used for?
Culturelle is a brand, and this page covers the LGG strain rather than any one product. To see which strains a Culturelle product lists and what its maker says it is for, read the product label and the maker’s product page. Then compare the strain names with the ones discussed here.
What are the side effects of Lactobacillus rhamnosus GG?
The Gut Check blog says that for most healthy people, LGG is safe and well tolerated. It describes the common side effects below, and the groups it says need caution.
| Effect or group | What the Gut Check blog reports |
|---|---|
| Mild bloating or gas | Usually resolves within 1 to 2 weeks |
| Temporary increase in bowel movements | Generally normalizes with continued use |
| Mild abdominal discomfort | More common at higher doses or with rapid initiation |
| Immunocompromised people | Rare cases of bacteremia have been reported |
| People with central venous catheters | A theoretical risk of contamination |
| People with severe acute pancreatitis | One study showed increased mortality with probiotic use |
| Premature infants | Should receive probiotics only under medical supervision |
For more on how studies report side effects, see probiotics side effects in studies (our research library).
Is Lactobacillus rhamnosus GG safe and regulated?
As of October 31, 2026, the Gut Check blog reports that the FDA has granted GRAS (Generally Recognized as Safe) status to multiple strains, and that the European Food Safety Authority has included L. rhamnosus on its QPS (Qualified Presumption of Safety) list. These are the blog’s statements. To check the status of a specific strain or product, start at the FDA’s home page. This is information, not legal advice.
What does Lactobacillus rhamnosus GG on a stool test mean?
Vibrant Wellness, which sells the Gut Zoomer test, says LGG is a key marker in its panel. The company says elevated levels may suggest a favorable gut environment, and low levels could signal an imbalance. Those are the company’s interpretations. Ask whoever ordered the test what the result means for you before you change anything.
How does LGG compare with other strains?
The 2022 review pairs LGG with Saccharomyces boulardii for shortening diarrhea, and with L. reuteri DSM 17938 for infant colic. For the yeast probiotic, see saccharomyces boulardii. For other strains on a label, see lactobacillus acidophilus.
Questions to ask your clinician
- Is a probiotic appropriate for my type of colitis, given my current medicines?
- If I take minocycline, should any probiotic be spaced from it, and do dairy or timing matter?
- Which of my antibiotics are most likely to affect my gut, and what should I watch for?
- Which study applies to my situation if I am considering LGG for diarrhea or anxiety?
- If a stool test lists LGG, what does the result mean for my care?
Practical next steps
- Read the exact strain name on any product label before you compare it with the strain discussed here.
- Bring your medicine list to your pharmacist before you start any probiotic.
- For a broader view of digestive topics, see digestive and oral health.
BioPhysics Essentials and Vibrant Wellness sell the products they describe. This page reports their statements as theirs. Some links on this page are affiliate links, and this site may earn a commission if you buy through them.
By Gut, Gum and Nail Health Editorial Team
This article is for general information purposes only and does not constitute medical advice. Consult your doctor or qualified healthcare provider before making changes to your health routine.