Throughout the study the following tools will be utilized (and variables assessed): a subject diary (for documentation of concomitant medications and concomitant medication changes and adverse events) the IBS-36 Questionnaire (for assessment of treatment-induced changes in the IBS-specific Quality of Life score), and a 6-point Likert Scale for IBS symptoms severity scoring. This tool and has been developed specifically for this study, based, in part, on similar scales in the published literature.