PERSUADE Study: I Guarantee That It Will …

Peppermint oil (PO) products have been promoted for irritable bowel syndrome (IBS) for quite a long time.  When I have recommended PO as a possible treatment, I frequently say that “I guarantee that it will….give you fresh breath.  It might help your stomach symptoms.”

A recent randomized, double-blind “PERSUADE” study (Zsa Zsa R. M. Weerts et al Gastroenterol 2020; 158: 123-36) shows that PO likely has some efficacy for stomach symptoms in IBS. This trial enrolled 189 patients & 178 completed study (mean age, 34 years, 78% female) from the Netherlands.  Subjects were divided in three groups -instructed to take the study capsule 3/day for 8 weeks:

  • 182 mg small-intestinal release PO-SI
  • 182 mg ileocolonic release PO-IC
  • Placebo

The primary endpoint was at least a 30% decrease in the weekly average of worst daily abdominal pain

Key findings:

  • The primary endpoint did NOT differ significantly between the three groups: PO-SI with 46.8%, PO-IC with 41.3%, and Placebo with 34.4% response.
  • The PO-SI but not PO-IC was associated in secondary improvements compared to placebo in abdominal pain (P=.06), discomfort (P=.02), and IBS severity (P=.02).
  • Adverse events were mild with PO, but more common than placebo. Adverse events included heartburn, belching, and headache.
  • The authors calculate that the number needed to treat with PO-SI would be 8 which is higher than recent ACG monograph which suggested an NNT of 4 (Am J Gastroenterol 2018; 113: 1-18).  Even an NNT of 8 compares favorably with other treatments: linaclotide 6, plecanatide 10, and eluxadoline 12.5.


  • the studied population was mainly young adult, predominantly white and female; thus the findings may not be generalized to other groups
  • the peppermint smell could have undermined blinding despite presentation in capsule form
  • relatively short duration study

The associated editorial by BD Cash (pgs 36-37) notes that PO medicinal use began in 1753 by Carl Linnaeus.  PO is thought to work via smooth muscle calcium channel antagonism.  The findings of working in the small intestine and not ileocolonic release could “spur additional therapeutic development.”

My take (borrowed in part from editorial): “These results reaffirm that PO can improve viscerosensory symptoms of IBS …and is well-tolerated… [It is] clearly not a gangbuster as a monotherapy.”  While the findings show modest effect, the findings are supported by a “robust” study as this is the first randomized, double-blind placebo-controlled clinical trial of PO.

Related blog posts:

Also, fidaxomicin has received FDA approval for pediatric use for C diff infections:

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