Peppermint leaf and peppermint oil have a long history of use for digestive disorders. Recent evidence suggests that enteric-coated peppermint oil may be effective in relieving some of the symptoms of irritable bowel syndrome. A combination product including peppermint oil and caraway oil seems to be moderately effective in the treatment of non-ulcer dyspepsia. Topical application of peppermint oil may be effective in the treatment of tension headache. Because of its relaxing effects on smooth muscle, peppermint oil given via enema has been modestly effective for relief of colonic spasm in patients undergoing barium enemas. Peppermint oil is well tolerated at the commonly recommended dosage, but it may cause significant adverse effects at higher dosages.