Is peppermint oil good for individuals with irritable bowel syndrome?

Peppermint oil appears to significantly improve symptoms of irritable bowel syndrome (IBS), as does placebo, with no significant differences between groups, reports a study.

A team of investigators conducted a 6-week, randomized, double-blind, placebo-controlled trial at a single academic centre in the US. Patients with IBS (Rome IV criteria), with moderate to severe symptoms based on the IBS Severity Scoring System (IBS-SSS score ≥175), were randomized to enteric-coated peppermint oil 180 mg three times daily or placebo in a 1:2 ratio.

In modified intent-to-treat analysis, substantial mean improvements were noted from baseline to 6 weeks in the mean change in IBS-SSS scores for both peppermint oil (90.8; standard deviation [SD], 75.3) and placebo (100.3; SD, 99.6).

The peppermint oil group reported numerically lower improvement than the placebo group, but the effect size was small (d, –0.11). In addition, no statistically significant between-group difference was observed (p=0.97). Both groups also showed substantial improvements on secondary endpoints, but there were no statistically significant between-group differences on any of the secondary measures.

Similar results were found in sensitivity analyses using multiple imputation to replace missing data. In addition, there were no significant differences seen between peppermint oil and placebo on any outcome measures.

“Further large, rigorous trials are needed to evaluate the role of peppermint oil for the treatment of IBS,” the investigators said.