Diarrhea irritable bowel syndrome(IBS-D）has seriously affected health and quality of life of patients.It may be important pathogenesis in development and recurrence of the process of IBS-D,excessive endoplasmic reticulum stress (ERS) activated PERK(proteinkinaseR-like ERkinase，PERK)-eIF2a(eukaryotic translation initiation factor 2 alpha,eIF2a) pathway and damaged intestinal mucosal epithelial Barrier. Tongxieyaofang(TXYF) had obtained satisfactory effect in treating IBS-D in clinic and previous study, but it is unknown that herbal formula how to work.This project applies metabolomics method to detect plasma,urine and stool metabolites for patients before and after treatment, to determine the effects of the"multiple ingredients"of TXYF in body.

Inclusion Criteria:

• Patients meeting the diagnostic criteria of Western medicine for IBS-D;
• aged 18-70 years old; with a baseline IBS-SSS score over 75 points;
• voluntarily signed the informed consent;
• local resident who could ensure follow-ups, with basic reading ability

Exclusion Criteria:

• Patients with IBS-C, -M, and uncertain forms;
• accompanied with serious lesions in major organs including heart, liver, and kidney, hematopoietic system diseases, and tumors;
• gastrointestinal organic disease (e.g., chronic pancreatitis), or systemic diseases affecting the digestive tract motion (e.g., hyperthyroidism,diabetes, chronic renal insufficiency, and nervous system diseases);
• undergoing or requiring constant use of drugs that may affect gastrointestinal functions (e.g., anti-cholinergic drugs, calcium channel blockers, 5-HT3 receptor antagonist, antidiarrheal agents, antacids, prokinetic agents, antidepressants, anxiolytics, and intestinal flora regulating drugs);
• with history of abdominal surgery (e.g., cholecystectomy);
• with an allergy history of tested drugs or severe allergy history of food;
• pregnant and lactating female;
• with a history of neurological or psychiatric disorders;
• or participating in other clinical trial.