Irritable bowel syndrome (IBS) is the most common functional bowel disorder with recurrent abdominal pain associating with defecation or a change in bowel habit. Several studies reported the efficacy of herbal medicines in improving IBS symptoms. This pilot study evaluated the efficacy of the herbal formula of Ocimmum basilicum (Reihan seeds), and Acasia arabica (Samgh-e-arabi) on symptoms severity score of patients with irritable bowel syndrome, Diarrhea predominant (IBS-D).

This double-blind randomized pilot controlled clinical trial (ethics code: IR.KMU.AH.REC1400.050), with parallel groups allocation ratio of 1:1, was conducted in a referral clinic of Afzalipour Hospital affiliated with Kerman University of Medical Sciences in Kerman, southeastern Iran. A total of 38 patients with IBS-D (diagnosed based on the Rome IV criteria) were included in this study. The patients with complications during the intervention, pregnancy or lactation, a history of allergy to herbal drugs, and severe organic or psychiatric disorders were excluded. The participants received one capsule containing 500 mg of Ocimmum basilicum seeds powder, and Acasia arabica powder; or placebo (Corn starch) three times a day, before meal, for 4 weeks. IBS Symptoms Severity Scale (IBS-SSS) were assessed via standard questionnaire.

A total 19 participants in each group completed the study, and their data were analyzed statistically. Abdominal pain severity, abdominal pain frequency, bowel habit dissatisfaction, and interaction with quality of life showed significant improvements in herbal formula group compared to the placebo without serious side effects. No significant difference was observed between the two groups in term of bloating/distention severity (independent t-test, P <0.05).

Although this pilot study showed the efficacy of this herbal formula in improving IBS-SSS, more studies with larger sample size are needed to confirm the efficacy and safety of this herbal fotmula in patients with IBS-D