Is Lactobacillus rhamnosus GG Safe with Metronidazole?
Free · No account · based on published sources including NIH ODS, FDA drug labels, and peer-reviewed literature
Separate administration by at least 2 hours. Take the probiotic at bedtime when metronidazole levels are declining. Extend probiotic use 2–4 weeks after completing metronidazole to support microbiome recovery, particularly if treating C. difficile-associated conditions.
Why this interaction occurs
Metronidazole has anaerobic bactericidal activity that can reduce viability of Lactobacillus strains in the GI tract. Additionally, metronidazole is commonly used for conditions where Lactobacillus supplementation is most beneficial (e.g., bacterial vaginosis, C. diff), making proper dosing timing critical to achieving therapeutic benefit from both agents.
Evidence
Evidence level: moderate.
Reported safety data
The FDA’s adverse event reporting system (FAERS) has received 52,138 reports mentioning Metronidazole. This reflects reported cases involving the medication in general — not confirmed causation, and not specific to the Metronidazole + supplement combination on this page.
FAERS reports are voluntary and cannot prove that a drug caused an event. Do not use report counts to assess the safety of this specific drug-supplement pair.
Frequently asked questions
Related interactions
All Lactobacillus rhamnosus GG interactions → · All Metronidazole interactions →
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Educational only — not medical advice.
Always confirm with your doctor or pharmacist.