This study is looking at how a drug called Psilocybin (TRP-8802) works with therapy for people who have Irritable Bowel Syndrome (IBS). IBS is a condition where the tummy hurts or feels funny, and you might need to go to the bathroom a lot. In the study, some people will get the treatment right away, and others will have to wait a bit. They'll take the drug two times, and they'll have therapy sessions before and after taking the medicine. The study will last about 52 days for the immediate group, but those who wait will have an extra 8 weeks before starting.

• The study includes a 28-day screening period and several weeks of treatment and therapy sessions.
• Participants will take the drug two times and have therapy sessions before and after.
• The study checks how the drug affects symptoms like pain and anxiety.

People who join must be between 21-64 years old, have IBS, and be willing to follow certain rules about medications and lifestyle during the study. This includes not using certain drugs, alcohol, or nicotine before and after taking the study medication.