Participants will then begin a 7-day screening diary of bowel habit and symptoms. This will be used to confirm frequency of IBS symptoms and IBS subtype. Participants will complete the Rome IV diagnostic questionnaire as part of their eligibility assessment. If there is a discrepancy between diary data and participant report on the Rome IV questionnaire, then the PI may decide to exclude the participant. To reduce patient burden, it will be acceptable to return completed diaries by post (prepaid envelope), by electronic communication (scan or photo), or in person.