Irritable Bowel Syndrome (IBS) is one of the most common luminal GI tract disorder. Multiple class of drugs and even psychotherapy modalities have been suggested for IBS treatment. Melatonin suggested in few studies for IBS treatment. The aim of this study was to determine the efficacy of oral melatonin on irritable bowel syndrome (IBS).

Forty patients with documented moderate to severe IBS diagnosis (Rom III) were randomized to receive either melatonin 3 mg or identically appearing placebo daily at bedtime for 8 weeks. A validated questionnaire, IBS-Severity Scoring System (IBS-SSS), was used to assess symptom severity and comparing the IBS symptoms before and after treatment, in both groups.

Improvements in IBS-SSS total scores were significantly greater after treatment with melatonin than with placebo (p=0.018). There was statistically significance decreased in bloating (p=0.023) and dissatisfaction of bowel habits(p=0.034) in melatonin than placebo. No significant side effects were seen in both groups.

We suggested that melatonin is a promising therapeutic agent for IBS.