NEUROMODULATION WITH TRANSCUTANEOUS AURICULAR VAGUS NERVE STIMULATION IN ADULTS WITH IRRITABLE BOWEL SYNDROME: A RANDOMIZED, SINGLE-BLIND, SHAM-CONTROLLED CROSSOVER STUDY

1. Male and female adults, aged 18 to 60 years, who can provide written, informed consent.

2. A diagnosis of IBS according to Rome IV criteria, as follows:

   a. Recurrent abdominal pain, on average, at least 1 day per week in the last 3 months, associated with 2 or more of the following criteria: i. Related to defecation. ii. Associated with a change in stool frequency. iii. Associated with a change in stool from (appearance). b. Criteria fulfilled for the last 3 months with symptom onset at least 6 months prior to diagnosis.

3. Completion of at least 4 of the 7 daily surveys during week prior to study intervention
4. Average daily abdominal intensity score between 4 and 8 (on a 10-point numeric rating scale) during week prior to study intervention.
5. Ability to read and speak English fluently.
6. Ability to provide own written informed consent (or assent) and comply with the requirements of the study.
7. Daily access to a computer with internet for online surveys

Exclusion Criteria:

1. Age under 18 years or over 60 years
2. Those who cannot provide informed consent.
3. Those who cannot read or speak English fluently.
4. Organic medical conditions associated with abdominal pain, including inflammatory bowel disease, celiac disease, peptic ulcer disease, chronic liver disease, cancer, or endometriosis.
5. Those who are pregnant, lactating, or intending to become pregnant during study period. Women of childbearing potential who are unwilling or unable to use effective contraception during the study period will also be excluded.
6. Those who have permanent implanted metal objects (e.g., stimulator, implants).
7. History of surgery involving the vagus nerve
8. History of abdominal surgeries other than appendectomy or cholecystectomy at least 6 months prior to study entry
9. Use of chronic opioids, benzodiazepines, glucagon-like peptide-1 receptor agonists
10. Underlying psychiatric conditions other than anxiety and depression on stable controlled medications in the past 6 months prior to study entry
11. Underlying neurological or neuropathic conditions, including history of seizures, cerebrovascular accident, uncontrolled migraines, traumatic brain injury, hydrocephalus, multiple sclerosis, movement disorder, complex regional pain syndrome, fibromyalgia
12. Presence of metallic prostheses, pacemakers, metal clips on blood vessels, metal parts in the eye, metallic intrauterine device, metal braces, facial tattoos and/or metal objects above the level of the neck
13. Dermatological conditions affecting the ear, face, or neck region, cuts or abrasions to the external ear that would interfere with ability to wear taVNS.