Objective: To discuss the clinical effects of Yichang Zhixie decoction on diarrhea predominant irritable bowel syndrome (IBS-D) and to investigate its influence on brain-gut peptide factors including serum 5-hydroxytryptamine (5-HT)

substance P (SP)

vasoactive intestinal peptide (VIP)

somatostatin (SS)

etc. Method: One hundred patients with IBS-D were randomly divided into the control group and the observation group (50 cases in each group). Patients in control group took orally 1 piece of flupentixol and melitracen tablet each morning and noon

and 2 g live combined bifidobacterium thrice daily. Based on the treatment of control group

patients in the observation group added 1 does of Yichang Zhixie decoction. Patients in both groups received a 4-week period of treatment. The digestive main symptom and the special quality of life scale (IBS-QOL) were scored before and after treatment. The prevalence and incidence situation of patients were recorded during 3-month period of follow-up. The levels of serum 5-HT

SP

VIP and SS were detected. Result: The clinical curative effect of observation group was superior to that of control group (P<0.05). The main digestive symptoms scores (abdominal pain

abdominal distension

defecation times

stool shape and mucous stool) in observation group were less than those in control group (P<0.01). IBS-QOL score of observation group was higher than that of control group after treatment and during follow-up period (P<0.01). The recurrence rate of observation group was 45.8%

which was inferior to 69.2% of control group during follow-up period (P<0.05). Levels of 5-HT

SP

VIP and SS in observation group were lower than those in control group (P<0.01). Conclusion: Yichang Zhixie decoction could reduce clinical symptoms

improve quality life and reduce long-term recurrence rate of IBS-QOL patients. Its action mechanism may be related to adjusting the levels of 5-HT

SP

VIP

and SS

although the exact mechanism deserves further study.