Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder characterized by recurrent abdominal pain and altered bowel habits. Under the Rome IV criteria, IBS can be classified into constipation-predominant (IBS-C), diarrhea-predominant (IBS-D), mixed (IBS-M), and unclassified (IBS-U) subtypes. IBS-D represents one of the most clinically disruptive phenotypes due to the combined burden of abdominal pain and frequent loose stools1. These symptoms are the major drivers of impaired quality of life and healthcare utilization. Despite available pharmacologic treatments, recurrence rates remain high and adverse effects often limit patient satisfaction, creating an unmet need for safe and effective alternative therapies.

Transcutaneous Electrical Acustimulation (TEA) is an emerging therapy which delivers appropriate electrical stimulation to acupoints that are in the vicinity of peripheral nerves through surface electrodes, has been demonstrated to improve bowel symptoms and visceral hypersensitivity by modulating autonomic function and brain-gut interaction2. Previous trials of TEA in IBS have shown improvement in bowel symptoms, pain, and quality of life, with good safety and tolerability2,3. However, multicenter evidence for IBS-D is lacking.

This trial aims to evaluate whether TEA can improve overall symptoms in patients with IBS-D. Specifically, the primary objective is to assess the effect of TEA on the composite responder rate, defined by concurrent improvement in both abdominal pain and loose stool days. Secondary objectives include evaluating broader symptom severity, stool characteristics, as well as on quality of life, psychological symptoms, and the durability of clinical benefits during follow-up.

Inclusion Criteria:1)Adults aged 18-65 years of either sex. 2)Diagnosis of diarrhea-predominant irritable bowel syndrome (IBS-D) will according to modified Rome IV criteria based on Asian consensus4: recurrent abdominal pain or discomfort (an unpleasant or bothersome sensation that is not described by the patient as pain, including fullness, bloating, or pressure), on average, at least 1 day per week in the last 3 months, associated with two or more of the following-related to defecation, associated with a change in stool frequency, or associated with a change in stool form-with symptom onset at least 6 months before diagnosis.

3)Mean daily abdominal pain score (APS) or abdominal discomfort score (ADS) ≥ 3 on a 0-10 Numerical Rating Scale (NRS) in the last week.

4)Type 6 or 7 of the Bristol Stool Form Scale (BSFS) appeared for at least 2 days in the last weeks.

5)Colonoscopy performed within the past 3 years without evidence of organic gastrointestinal disease. Patients with colonic polyps or colonic diverticula may be included, provided there are no related complications.

6)Willingness and ability to comply with all study procedures, and provide written informed consent.

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Exclusion Criteria:1)Presence of organic gastrointestinal diseases (e.g., inflammatory bowel disease, celiac disease and gastrointestinal malignancy).

2)Patients who cannot commit to abstaining from any IBS-targeted medications (e.g., antidiarrheals, antispasmodics, rifaximin, 5-HT3 antagonists, opioid analgesics, or other agents affecting bowel habits or visceral pain perception) or centrally acting drugs (Antidepressants or anxiolytics) throughout the study period. Patients with long-term stable use (at least 3 months) of probiotics/synbiotics who do not intend to change their regimen during the treatment period may be included.

3)Prior major abdominal surgery (except appendectomy, cholecystectomy). 4)Severe cerebrocardiovascular diseases, impaired hepatic or renal function indicating organ failure, uncontrolled diabetes or hyperthyroidism, or uncontrolled psychiatric disorders.

5)Implanted electrical devices (e.g., cardiac pacemaker, defibrillator) or other active implants that may be affected by electrical stimulation.

6)Local skin disease or infection at the stimulation site, severe dermatologic sensitivity to electrodes or adhesives.

7)Participants who are familiar with acupuncture acupoints and may therefore compromise study blinding will be excluded.

8)Pregnancy or lactation. Women of childbearing potential who cannot confirm non-pregnancy will be required to undergo a urine or serum hCG test during screening, those with positive results will be excluded.

9)Participation in another clinical trial within the past 3 months or currently enrolled in another interventional study.

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