This randomized control trial aims to evaluate the effect of transcutaneous auricular vagal nerve stimulation in patients with irritable bowel syndrome. The intervention will be 8 weeks of treatment with a vagal nerve stimulator. The main objectives are:

• To evaluate the clinical response, defined as a decrease of at least 50 points on the IBS-SSS questionnaire, of the treatment.
• To ascertain whether the autonomic-vagal neurosignature, derived from pre-treatment registration of symptom profiles, autonomic responses and imaging of neuronal activity as a reaction to stress is able to predict therapeutic response to tVNS accurately.
• To evaluate the effect of treatment on quality of life
• To evaluate the effect of treatment on depression
• To evaluate the effect of treatment on anxiety Participants will be asked to wear a wearable (Fitbit) and fill out a daily questionnaire for one week. Thereafter, a functional brain MRI will be performed.

In the intervention group patients will receive transcutaneous nerve stimulation for 8-weeks at home. The comparison group will receive the same device but with a non-conducting electrode.

Patients fill out weekly questionnaires during the treatment period and at follow-up moments 3 and 6 months after finishing the treatment period.

Inclusion Criteria:

• A diagnosis of IBS according to Rome IV criteria (3), as follows:
• 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:
• Related to defecation.
• Associated with a change in stool frequency.
• Associated with a change in stool from (appearance).
• Criteria fulfilled for the last 3 months with symptom onset at least 6 months prior to diagnosis.
• Age between 18 and 75 years;
• Ability to understand and speak the Dutch language.
• Ability to understand how to utilize the ESM application.

Exclusion Criteria:

• A history of abdominal surgery, except for uncomplicated appendectomy, laparoscopic cholecystectomy and hysterectomy is present or otherwise based on the principal investigator's judgement.
• Presence of metallic prostheses, pacemakers, metal clips on blood vessels, metal parts in the eye, an intrauterine device (with the exception of the Mirena IUD), metal braces, facial tattoos and/or metal objects.
• History of major head trauma or head/brain surgery
• History of claustrophobia
• Pregnancy, lactation, intention to become pregnant during the study period
• Students and employees of Maastricht University are not precluded from participation, unless they have a direct personal, professional or hierarchical position with regards to any of the study team members or their department.
• If the subject has a cardiac arrhythmia, the attending physician will be consulted before participation.