This study will serve as a pilot randomized controlled trial to assess the feasibility of Psilocybin-Assisted Psychotherapy (PAP) in Treating Irritable Bowel Syndrome (IBS). Patients with severe IBS will undergo 3 pre-psychotherapy sessions with two licensed and trained psychedelic therapists, then will be randomized to undergo a guided psychotherapy session with single 25 mg oral "high" dose of psilocybin or a single 100 mg dose of niacin (active placebo) and attend 4 post-therapy integration sessions.
Severe IBS patients meeting Rome IV criteria. Severe IBS is defined by IBS-SS >300, or one or more emergency room (ER) visit for abdominal pain in the last year.
Experiencing persistent IBS symptoms despite pharmacologic therapy
Have an identified support person
Agree to be accompanied home (or to an otherwise safe destination) by the support person, or another responsible party, following dosing
Congestive heart failure
Clinically significant arrhythmias (e.g.,
Ventricular fibrillation, torsades) or clinically significant ECG abnormality (i.e., corrected QT interval > 450)
Recent acute myocardial infarction or