Lactobacillus rhamnosus GG
The most-studied single probiotic strain on earth. The go-to for antibiotic-associated and traveler's diarrhea.
Strong for antibiotic-associated diarrhea (Cochrane support), pediatric acute gastroenteritis (reduces duration ~1 day), traveler's diarrhea prevention. Moderate for IBS-D, eczema prevention in at-risk infants. Effects: within days for acute diarrhea.
L. rhamnosus GG (LGG) was isolated by Goldin and Gorbach in 1985 (hence the GG) and has been the subject of more clinical trials than any other probiotic strain — well over 300. It's a hardy strain that survives stomach acid, adheres to intestinal mucosa, and produces lactic acid and antimicrobial compounds that displace pathogens. Strongest evidence is in antibiotic-associated diarrhea, C. difficile prevention, traveler's diarrhea, and pediatric acute gastroenteritis. Sold most prominently as Culturelle.
- Form
- Culturelle (brand-name LGG). Generic LGG also widely available. Refrigerated forms preserve potency longer; shelf-stable spore versions are fine for travel.
- Dose
- 10–20 billion CFU/day. Trials use 10 billion.
- Timing
- With food or shortly before. Separated by 2 hours from oral antibiotics.
- Schedule
- Daily during antibiotic course + 1–2 weeks after. Travel: starting a few days before trip and continuing throughout.
- Side effects
- Mild gas and bloating during the first 1–2 weeks. Rarely allergic reactions.
- Interactions
- Take 2 hours apart from oral antibiotics.
- Contraindications
- Severe immune compromise (organ transplant, neutropenia, advanced HIV) — rare sepsis risk. Central venous catheter. Critical illness.
- Lab markers
- Not standard. Symptom tracking.
- Food sources
- L. rhamnosus is present in some yogurts and fermented dairy — but the specific GG strain is only reliably delivered via supplements / Culturelle products.
Pairs with
Saccharomyces boulardii (different mechanism — additive against C. diff). Prebiotics (feed the bacteria). Lactoferrin (gut barrier).
within Probiotics & gut