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Moderate evidenceGut health

Lactobacillus Rhamnosus GG

The most-studied probiotic strain in the world, with decent meta-analytic support for antibiotic-associated diarrhoea — but a large, rigorous NEJM trial found it completely ineffective for acute gastroenteritis in children, which should temper expectations considerably.

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What the science says

  • No benefit for acute gastroenteritis in children (high-quality trial) Strong evidence

    In a double-blind trial of 971 children aged 3 months to 4 years (Schnadower, NEJM 2018), LGG at 10^10 CFU twice daily for 5 days produced no difference from placebo in moderate-to-severe gastroenteritis outcomes, duration of diarrhoea, vomiting or missed daycare days. This directly contradicts earlier, smaller, lower-quality meta-analyses and is the strongest single piece of evidence on the question.

  • Shortens acute diarrhoea — but mainly in older, lower-quality trials Limited evidence

    A 2019 meta-analysis update found LGG shortened diarrhoea duration by roughly a day, with the effect concentrated in European trials and largely absent in Asian populations and in trials at low risk of bias. Once the large rigorous trials are weighted properly, the benefit shrinks toward nothing; efficacy also appears reduced in rotavirus-vaccinated children.

  • Prevents antibiotic-associated diarrhoea Moderate evidence

    Pooled RCTs support LGG for reducing antibiotic-associated diarrhoea in children and adults, with risk reductions broadly comparable to S. boulardii (relative risk around 0.5) at 10-20 billion CFU/day. This remains its best-supported use.

  • Prevents atopic dermatitis or allergy Limited evidence

    Perinatal LGG showed benefit for eczema prevention in early Finnish trials but failed to replicate in later trials in other populations, and effects on asthma and food allergy have been consistently null. Population-specific at best.

Dosage & safety

Studied dose10^9 to 10^10 CFU (1-10 billion) once or twice daily. Trials for antibiotic-associated diarrhoea used 10-20 billion CFU/day started with the antibiotic and continued 1-2 weeks after. Take bacterial probiotics at least 2 hours apart from an antibiotic dose.
SafetyWell tolerated in healthy people; transient gas and bloating are common in the first days. Documented cases of LGG bacteraemia, endocarditis and liver abscess exist, essentially all in immunocompromised patients, those with central venous catheters, short bowel syndrome, or damaged heart valves — avoid in those groups. Probiotics should not be given to critically ill patients outside a trial: a landmark trial of a Lactobacillus-containing product in severe acute pancreatitis found increased mortality. Product quality varies widely; CFU counts decline with heat and time, so check expiry-dated potency rather than at-manufacture counts.

How to take it

TimingOnce or twice daily at a consistent time, and at least 2 hours away from any antibiotic dose.
With food?With a meal — food buffers stomach acid and more bacteria survive the transit.
Worth knowingBuy on CFU guaranteed at the expiry date, not at manufacture, and do not leave the bottle in a hot car.

Interactions

With medications

  • antibiotics

    An antibiotic taken at the same time kills the live bacteria before they reach the gut. separate by at least 2 hours

  • immunosuppressants and chemotherapy

    Nearly all reported cases of LGG bacteraemia and endocarditis occurred in immunocompromised patients. do not use while immunosuppressed without medical supervision

Well-established interactions only — this is not a complete list. Always tell your doctor and pharmacist what you take.

Frequently asked questions

Does Lactobacillus rhamnosus GG help diarrhea in children?

For acute gastroenteritis, strong evidence says no: a trial of 971 children found Lactobacillus rhamnosus GG no better than placebo for diarrhoea duration, vomiting or severity. Earlier positive results came mostly from smaller, lower-quality trials.

Does Lactobacillus rhamnosus GG prevent antibiotic-associated diarrhea?

Yes, with moderate evidence — preventing antibiotic-associated diarrhoea is Lactobacillus rhamnosus GG's best-supported use, at 10-20 billion CFU/day. Start with the antibiotic and continue 1-2 weeks after.

Should I take LGG apart from antibiotics?

Yes — take Lactobacillus rhamnosus GG at least 2 hours away from any antibiotic dose, since the antibiotic kills the live bacteria. Taking LGG with a meal helps more bacteria survive stomach acid.

Is Lactobacillus rhamnosus GG safe?

Lactobacillus rhamnosus GG is well tolerated in healthy people, with transient gas and bloating in the first days. Rare bacteraemia and endocarditis have occurred, almost all in immunocompromised patients or those with central lines or damaged heart valves, so avoid LGG in those groups.

Scientific references

Where to buy

Swanson Vitamins, Lactobacillus Rhamnosus With FOS, 60 Vegan Capsules

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