Peppermint is a herb with spasmolytic, carminitive properties; the active constituent, menthol, has been shown to relax smooth muscle by blocking Ca2+ channels in the gut. This was a randomized double-blind placebo-controlled study of 90 patients with irritable bowel syndrome (IBS). Subjects took one enteric coated capsule containing 0.2 ml of peppermint oil (Colpermin) or placebo three times daily 30 minutes before each meal for 8 weeks. Patients’ symptoms and quality of life were assessed after the first, fourth, and eighth weeks. The number of patients who were free from abdominal pain or discomfort changed 0 at baseline to 14 (42.5%) at week 8 in the peppermint oil group, compared to from 0 to 6 (22.2%) in the control group (P < 0.001). The severity of abdominal pain was also significantly reduced in the peppermint oil group as compared to controls (p<0.001). Peppermint oil significantly improved patients’ quality of life. There were no significant adverse reactions. The peppermint oil preparation Colpermin is safe and effective in reducing abdominal pain or discomfort in patients with IBS. (Dig Dis Sci. 2010 May;55(5):1385-90.) PMID: 19507027
