Kliger B, Chaudhary S. Peppermint oil Am Fam Phys. 2007;75:1027-1030.Peppermint (Mentha x piperita) leaf and oil have been used historically to treat digestive disorders, to manage gallbladder disease, and to relieve headaches. The authors present an overview of the pharmacology of peppermint oil; its uses and effectiveness; the contraindications, adverse effects, and interactions related to its use; and the proper dosage.
The active constituents in peppermint oil, which is prepared through distillation of the ground parts of peppermint, include menthol, menthone, cineol, and several other volatile oils.1
Most studies on peppermint oil involve its use as a treatment of irritable bowel syndrome (IBS). Although studies have yielded mixed results, the authors report a trend indicating its mild effectiveness in reducing some IBS symptoms, especially flatulence and abdominal pain and distension. The authors cite two trials -- one in adults and one in children -- that reported modest but statistically significant benefits, most notably a reduction in severity of abdominal pain.
Because of its relaxing properties on smooth muscle, peppermint oil given via enema was examined in two trials and was shown to be modestly effective for relief of colonic spasm in patients undergoing barium enemas.
After reviewing several clinical trials and a meta-analysis of several trials, the authors suggest that combining enteric-coated peppermint oil and caraway oil seems to be moderately effective in treating non-ulcer dyspepsia.
The authors cite two trials that have shown that the topical application of peppermint oil is effective in reducing symptoms of tension headache.
Like many essential oils, peppermint oil can be toxic at excessive dosages and has been associated with interstitial nephritis and acute renal failure.2 It is contraindicated in patients with hiatal hernia, gallbladder disease, or gastroesophageal reflux disease, and should be used with caution during pregnancy and lactation. Common adverse effects reported in clinical trials include allergic reactions, heartburn, perianal burning, blurred vision, nausea, and vomiting.3 The authors report that laboratory studies suggest that peppermint leaf and peppermint oil may inhibit the cytochrome P450 1A2 system, which could lead to increased serum levels of drugs such as amitriptyline, cyclosporine, and haloperidol in patients who regularly consume large amounts of the leaf or oil.
The therapeutic dosage range in most IBS trials was 0.2 to 0.4 mL of peppermint oil taken three times daily in enteric-coated capsules. In children older than 8 years, the dosage is 0.1 to 0.2 mL three times daily.
1Blumenthal M, Goldberg A, Brinckmann J, eds. Herbal Medicine: Expanded Commission E Monographs. Austin, TX: American Botanical Council; Newton, MA: Integrative Medicine Communications; 2000.
2Schulz V, Hansel R, Tyler VE. Rational Phytotherapy: A Physician's Guide to Herbal Medicine. 3rd ed. New York, NY: Springer; 1998.
3Pittler MH, Ernst E. Peppermint oil for irritable bowel syndrome: a critical review and metaanalysis. Am J Gastroenterol. 1998;93:1131-1135.