Efficacy and Safety of Changkang Granules in the Treatment of Irritable Bowel Syndrome With Predominant Diarrhea (Liver qi Affecting the Spleen Pattern)

Inclusion Criteria: * Participants must meet all of the following inclusion criteria to be eligible for this trial: 1. Age 18-65 years (inclusive), regardless of gender; 2. Meet the Western medical diagnostic criteria for Irritable Bowel Syndrome with Predominant Diarrhea (Rome IV); 3. Meet the Traditional Chinese Medicine diagnostic criteria for Liver qi affecting the spleen pattern 4. Have a weekly average NRS score for abdominal pain ≥3.0 during the Run-In Period period, and have at least 2 days per week with stool form of type 6 or 7 (Bristol Stool Scale) during the Run-in period; 5. Have an IBS-SSS score \>175 at baseline; 6. Have completed a colonoscopy within the past 12 months prior to the Run-in period, and meet one of the following conditions: ① Normal colonoscopy results with no organic changes; ② Abnormal colonoscopy report, such as hemorrhoids, polyps (diameter ≤5mm and number ≤3), etc., which the investigator determines can be included; ③ Previous colonoscopy report indicating polyps \>5mm in diameter or \>3 in number, which after endoscopic treatment 6 months ago, residual polyps are ≤5mm in diameter and ≤3 in number, and the investigator determines can be included; 7. Voluntarily sign the informed consent form, and from the time of signing the informed consent form until the end of the last visit of the trial, the participant voluntarily accepts health education and maintains their usual diet and lifestyle, such as not changing dietary structure or exercise patterns. Exclusion Criteria: * Subjects with any of the following conditions are not eligible for enrollment in this study: 1. Subjects who have less than 3 spontaneous bowel movements per week during the run-in period; or at least 2 days per week during the run-in period with stool consistency classified as type 1 or 2 on the Bristol Stool Scale; 2. Patients with a history of severe mental or psychological disorders, or those scoring ≥63 on the Self-Rating Depression Scale (SDS), or ≥60 on the Self-Rating Anxiety Scale (SAS) during the screening period; 3. Patients with a confirmed history of organic gastrointestinal diseases, including both gastrointestinal and non-gastrointestinal digestive system diseases, such as chronic superficial gastritis with erosions or bleeding of grade II or higher, chronic atrophic gastritis, peptic ulcers, inflammatory bowel disease, intestinal tuberculosis, intestinal ulcers, intestinal obstruction, intestinal adhesions, eosinophilic gastroenteritis, cholelithiasis with recurrent cholecystitis (patients with gallstones or gallbladder polyps ≤0.5 cm in diameter and no significant symptoms may be exempted from exclusion upon investigator's judgment), tuberculous peritonitis, liver cirrhosis, and digestive system tumors, etc.; 4. Patients diagnosed with other diseases that affect the evaluation of abdominal pain and diarrhea, such as diarrhea caused by lactose intolerance, diarrhea after cholecystectomy, abdominal pain due to endometriosis, abdominal pain caused by hepatic and biliary stones or cholecystitis, abdominal pain due to chronic pancreatitis, etc.; 5. Patients with a history of systemic diseases affecting gastrointestinal function, such as diabetes mellitus, hyperthyroidism or hypothyroidism, chronic renal insufficiency, autoimmune diseases (such as allergic colitis, allergic purpura, Behcet's syndrome, systemic lupus erythematosus), etc.; 6. Patients with a history of major abdominal surgery involving the gastrointestinal tract, liver, gallbladder, spleen, or pancreas (subjects who have undergone appendectomy or cesarean section without impact on gut function may be exempted from exclusion upon investigator's judgment); 7. Patients with unexplained recurrent positive fecal occult blood, unintentional weight loss, anemia, fever, or jaundice prior to screening; 8. Abnormal liver function at baseline (ALT or AST \>1.5 times the upper limit of normal) or abnormal renal function at baseline (Cr \>upper limit of normal); 9. Patients with a history of severe diseases in the respiratory, cardiovascular, cerebral, hepatic, renal, endocrine, immune, hematopoietic systems, as well as tumors and neurological diseases, deemed unsuitable for participation in this trial by the investigator; 10. Patients who have used prokinetic agents, anticholinergic drugs, calcium channel blockers (excluding antihypertensive drugs), 5-HT3 receptor antagonists, antidiarrheals, antidepressants, anxiolytics, probiotics, analgesics, laxatives, etc., within 4 weeks before randomization; 11. Patients who took rescue medication (piroxicam) during the run-in period; 12. Pregnant or breastfeeding women, or those planning to conceive within 1 month after enrollment until the end of the trial; 13. Patients suspected or known to be allergic to the investigational drug, rescue medication, or its components; 14. Patients suspected or known to have a history of alcohol or drug abuse; 15. Patients who participated in another interventional clinical trial and took investigational drugs within 1 month before screening; 16. Patients whom the investigator deems unsuitable for clinical trial participation for any other reason.