Objective To determine the effect of fibre, antispasmodics,and peppermint oil in the treatment of irritable bowel syndrome.

Review methods Randomised controlled trials comparing fibre,antispasmodics, and peppermint oil with placebo or no treatmentin adults with irritable bowel syndrome were eligible for inclusion.The minimum duration of therapy considered was one week, andstudies had to report either a global assessment of cure orimprovement in symptoms, or cure of or improvement in abdominalpain, after treatment. A random effects model was used to pooldata on symptoms, and the effect of therapy compared with placeboor no treatment was reported as the relative risk (95% confidenceinterval) of symptoms persisting.

Results 12 studies compared fibre with placebo or no treatmentin 591 patients (relative risk of persistent symptoms 0.87,95% confidence interval 0.76 to 1.00). This effect was limitedto ispaghula (0.78, 0.63 to 0.96). Twenty two trials comparedantispasmodics with placebo in 1778 patients (0.68, 0.57 to0.81). Various antispasmodics were studied, but otilonium (fourtrials, 435 patients, relative risk of persistent symptoms 0.55,0.31 to 0.97) and hyoscine (three trials, 426 patients, 0.63,0.51 to 0.78) showed consistent evidence of efficacy. Four trialscompared peppermint oil with placebo in 392 patients (0.43,0.32 to 0.59).

Conclusion Fibre, antispasmodics, and peppermint oil were allmore effective than placebo in the treatment of irritable bowelsyndrome.