Participants with a diagnosis of IBS will be enrolled as defined by Rome IV criteria and will be classified into cohorts according to the Rome IV classification of IBS subtypes.
Each cohort (Cohort C and Cohort D) will recruit participants who will randomly receive either Blautix or matching placebo in a 1:1 ratio overall of treated to control participants.
Participants will undergo five visits in total across approximately 13 weeks. During the study treatment phase, participants will be asked to complete a variety of Quality of Life questionnaires at certain time points. These will consist of abdominal pain intensity score, IBS symptom severity (IBS-SSS), IBS quality of life (IBS-QoL), hospital anxiety and depression score (HADS), stool frequency, stool consistency & food frequency questionnaire.
Participants will be required to produce relevant blood, urine and faecal samples at pre-determined timepoints from screening through to End of Treatment and follow up visits.