Peppermint oil and placebo are similarly effective in alleviating symptoms of moderate to severe irritable bowel syndrome

Reference

Nee J, Ballou S, Kelley JM, et al. Peppermint oil treatment for irritable bowel syndrome: a randomized placebo-controlled trial. Am J Gastroenterol 2021;116(11):2279-2285.

Synopsis

These authors report the double-blind component of a larger trial of peppermint oil that had both an open-label phase and a double-blind phase. The authors randomized 133 adults with moderate to severe irritable bowel syndrome (IBS) (IBS Severity Scoring System [IBS-SSS] score of at least 175) 2:1 to receive 6 weeks of either peppermint oil (one 180-mg enteric-coated capsule three times daily) or placebo. At the end of 6 weeks, the study had a worrisome number of dropouts: 25% of all participants (35% of the intervention group and 18% of the placebo group). This seems inordinately high for such a short study period. The authors used a modified intention-to-treat analysis to assess the change in the IBS-SSS score. High numbers of dropouts and this analytic plan generally tend to favor the intervention. Although both groups showed improvement in their IBS-SSS scores (mean = 100.3 for placebo vs 90.8 for peppermint oil), the net difference was not statistically significant. Adverse events, mostly gastrointestinal, were more common in those taking peppermint oil (72% vs 51%; P = .03). Although dropouts due to adverse events occurred almost twice as frequently in those treated with peppermint oil (17% vs 9%), the difference was not statistically significant.