Melatonin improves bowel symptoms in female patients with irritable bowel syndrome: a double-blind placebo-controlled study

Aliment Pharmacol Ther. 2005 Nov 15;22(10):927-34. doi: 10.1111/j.1365-2036.2005.02673.x.


Background: Melatonin is involved in the regulation of gastrointestinal motility and sensation.

Aim: To determine the potential therapeutic effects of melatonin in irritable bowel syndrome (IBS).

Method: Seventeen female patients satisfying the Rome II criteria for IBS were randomized to receive either melatonin 3 mg nocte or identically appearing placebo 1 nocte for 8 weeks, followed by a 4-week washout period and placebo or melatonin in the reverse order for another 8 weeks. Three validated questionnaires - the GI symptom, the sleep questionnaires and the Hospital Anxiety and Depression Scale - were used to assess symptom severity and to compute the IBS, sleep and anxiety/depression scores, respectively.

Results: Improvements in mean IBS scores were significantly greater after treatment with melatonin (3.9 +/- 2.6) than with placebo (1.3 +/- 4.0, P = 0.037). Percent response rate, defined as percentage of subjects achieving mild-to-excellent improvement in IBS symptoms, was also greater in the melatonin-treated arm (88% vs. 47%, P = 0.04). The changes in mean sleep, anxiety, and depression scores were similar with either melatonin or placebo treatment.

Conclusions: Melatonin is a promising therapeutic agent for IBS. Its therapeutic effect is independent of its effects on sleep, anxiety or depression.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Adult
  • Aged
  • Anxiety / drug therapy
  • Anxiety / etiology
  • Depressive Disorder / drug therapy
  • Depressive Disorder / etiology
  • Double-Blind Method
  • Female
  • Gastrointestinal Agents / therapeutic use*
  • Humans
  • Irritable Bowel Syndrome / complications
  • Irritable Bowel Syndrome / drug therapy*
  • Melatonin / therapeutic use*
  • Middle Aged
  • Sleep Wake Disorders / drug therapy
  • Sleep Wake Disorders / etiology
  • Surveys and Questionnaires


  • Gastrointestinal Agents
  • Melatonin