Peppermint Oil for the Treatment of Irritable Bowel Syndrome or Functional Abdominal Pain in Children: the MINT Study

Inclusion Criteria: * Children aged between 8 years and 18 years * Diagnosis of IBS or FAP-NOS according to the Rome IV criteria. According to these criteria, organic disorders will be ruled out after routine laboratory testing initiated by their general practitioner or treating physician as part of standard of care. In patients without alarm symptoms only celiac screening (anti-transglutaminase antibodies and IgA), and faecal calprotectin are necessary.37 In patients with diarrhea faecal testing for Giardia Lambliae will be added. If alarm symptoms are present, further diagnostic testing (like a full blood count, CRP, liver tests or an ultrasound) to rule out an organic disorder, is left to the discretion of the treating physician. * An average daily pain rate of ≥ 3 of 10 on the Wong Baker Faces Pain Scale (This is a validated pain scale to measure pain intensity). Informed Consent by both parents and by children aged ≥ 12 years. No informed consent from parents is necessary for children \>16 years. Exclusion Criteria: * Current treatment by another health care professional for abdominal symptoms * Previous use of peppermint oil for these abdominal complaints * Known hypersensitivity to mints or peppermint oil * Gastrointestinal blood loss * Recurrent or unexplained fevers * Decreased growth velocity * History of previous abdominal surgeries in the past 3 months * Significant chronic health condition requiring specialty care (e.g., lithiasis, ureteropelvic junction obst…