After analyzing over 40 probiotics across 69 trials, we’ve identified the most promising probiotics for managing nausea or vomiting in IBS. Our dataset (below) is ordered based on an automated scoring system, which we further refined using additional criteria (below) to select our top choices. Here are the results of our findings.

Our Top Choice(s)

• Lactospore (Bacillus coagulans MTCC 5856) 

Diarrhea Relief:
Lactospore has shown great promise in relieving diarrhea symptoms, particularly in adults with IBS-D (diarrhea-predominant IBS). In a small but encouraging study, participants experienced a 45.1% reduction in stool frequency over 90 days. Stool consistency also improved, with many shifting from loose stools to a more normal form. The effect size for stool frequency reduction was notably large, with a Cohen’s d of 2.93—indicating a substantial impact. Lactospore also had a strong effect size of 1.30 for overall diarrhea relief. (1)

Vomiting Relief:
In the same study, Lactospore also proved effective in reducing vomiting symptoms. Participants saw a 47% decrease in vomiting scores, a result that was statistically significant (p=0.0013) and had a large effect size (Cohen’s d = 1.89). This means that Lactospore had a meaningful and positive effect on vomiting symptoms in those with IBS-D. (1)

Our Criteria

The probiotics in our full database (below) are automatically ranked based on their 1) effect size for diarrhea, nausea, or vomiting relief, followed by 2) effect size for overall IBS symptoms (‘Global IBS Symptoms’), and finally by 3) the quality of evidence from the studies.

For this summary, we selected our top choices based on these rankings, along with the following additional criteria: 

• Evidence Quality Score: We only included probiotics backed by studies with an evidence quality score of 75% or higher.
• Effect Size: Only probiotics that demonstrated a moderate to high effect size (>0.5) for diarrhea, nausea, or vomiting relief made the cut.
• Clear Dosing Information: Only probiotics with clear and reliable dosing data were included.
• Commercial Availability: Probiotics needed to be commercially available to consumers.

No Direct Comparisons

It’s important to note that there are no direct comparisons between the probiotics in our database across identical study methods, so we can’t definitively rank one probiotic as superior to another. Lactospore shows promise for diarrhea and vomiting relief in IBS-D, but as with all probiotic supplements, always consult your healthcare provider before starting.

*Population values represent the per protocol population size from studies specifically assessing the above parameters.
*Effect sizes are reported as the weighted mean effect size across studies.

References

1. Majeed, M., Nagabhushanam, K., Natarajan, S. et al. Bacillus coagulans MTCC 5856 supplementation in the management of diarrhea predominant Irritable Bowel Syndrome: a double blind randomized placebo controlled pilot clinical study. Nutr J 15, 21 (2015). https://doi.org/10.1186/s12937-016-0140-6

When selecting our top probiotic picks, we ensure they are commercially available and backed by high-quality evidence, with an average score above 75% for the relevant symptom parameters. The probiotics must also demonstrate a moderate to high effect size (>0.5) for these symptoms. If there are more than five candidates, we limit our top picks to the best five based on the effect size for relevant symptoms and Global IBS symptoms, as well as evidence quality. This ensures our recommendations are practical and reliable.

When selecting our top probiotic picks, we ensure they are commercially available and backed by high-quality evidence, with an average score above 75% for the relevant symptom parameters. The probiotics must also demonstrate a moderate to high effect size (>0.5) for these symptoms. If there are more than five candidates, we limit our top picks to the best five based on the effect size for relevant symptoms and Global IBS symptoms, as well as evidence quality. This ensures our recommendations are practical and reliable.