Peppermint oil is commonly prescribed to treat irritable bowel syndrome (IBS) without any evidence from high-quality controlled trials. This double-blind study (NCT02716285) evaluated the safety and efficacy of small-intestinal–release peppermint oil and ileocolonic-release peppermint oil for the treatment of IBS in patients that met Rome IV criteria. Primary outcome measures included the Food and Drug Administration (FDA) definition of abdominal pain response (a 30% decrease in the weekly average compared to the baseline of 4 weeks prior) as well as the European Medicines Agency for overall relief of IBS symptoms. Secondary endpoints included abdominal pain, discomfort, symptom severity, and adverse events.
Neither primary endpoint of abdominal pain response (as defined by the FDA) nor overall relief of symptoms (as defined by the European Medicines Agency) was met. Abdominal pain improvement was noted in 29/62 patients (46.8%, P=0.170 vs placebo) in the small-intestinal–release group, 26/63 patients (41.3%, P=0.385 vs placebo) in the ileocolonic-release group, and 22/64 (34.4%) patients in the placebo arm. Moreover, there was no difference among groups in overall relief with small-intestinal release (9.7%, P=0.317), ileocolonic release (1.6%, P=0.351), or a placebo (4.7%). It is worthwhile to note that the small-intestinal peppermint oil capsule did produce improvements in secondary outcomes, including abdominal pain (P=.016), discomfort (P=.020), and IBS severity (P=.020).
These findings do not support ileocolonic-release peppermint oil capsules for treatment of IBS. However, it is reasonable to recommend small-intestinal–release peppermint oil in patients with IBS given its minimal side effect profile, outcomes indicating improvement of symptoms, and easy accessibility.
Weerts ZZRM, Masclee AAM, Witteman BJM, et al. Efficacy and safety of peppermint oil in a randomized double-blind trial of patients with irritable bowel syndrome. Gastroenterology
2019 Aug 27. (Epub ahead of print) (https://doi.org/10.1053/j.gastro.2019.08.026