Lactobacillus

Best for

Prevent diarrhea from antibiotics

Likely strong benefit · 1 meta-analysis , n=8k

6 papers · 2 claims · 20 outcomes scored · 1 positive

Outcomes

What lactobacillus actually does, by outcome

Each row is one outcome with effect size, evidence base, the dose that worked in trials, and time to first effect. Magnitude tiers come from native-unit MCID where available, Cohen's d otherwise.

Outcome Effect size Evidence Dose Weeks Rank

Prevent diarrhea from antibiotics Likely strong benefit

Keeps your gut stable while antibiotics do their job.

1 meta-analysis n=8.0k — — #1/5

26955289

large

1 meta-analysis n=8.0k Meta-analyzed

—

#1 /5

Grow beneficial gut bacteria Not enough research

The species that produce vitamins and crowd out harmful bugs gain ground.

1 RCT n=— — 4 wk

35744774

—

1 RCT n=—

—

4 wk

—

Outcome	Effect	Evidence	Dose	Weeks	Rank
Prevent diarrhea from antibiotics Likely strong benefit	large	1 meta-analysis n=8.0k Meta-analyzed	—	—	#1/5
Grow beneficial gut bacteria Not enough research		1 RCT n=—	—	4 wk	—

Risk profile

Adverse events and known drug interactions

Safety events

D-lactic acidosis severe

headache mild

flatulence mild

muscle pain (myalgia) mild

muscle weakness mild

gastrointestinal upset / dyspepsia mild

itchy scalp mild

vomiting

Sources

Generated August 14, 2026

Lactobacillus

What lactobacillus actually does, by outcome

Adverse events and known drug interactions

More evidence for Lactobacillus

Bifidobacterium (unspecified)

Bifidobacterium adolescentis

Fructo-Oligosaccharides

Oligosaccharide (unspecified)

Lactobacillus

More evidence for Lactobacillus

NewBifidobacterium (unspecified)

NewBifidobacterium adolescentis

NewFructo-Oligosaccharides

NewOligosaccharide (unspecified)

Bifidobacterium (unspecified)

Bifidobacterium adolescentis

Fructo-Oligosaccharides

Oligosaccharide (unspecified)