Amitriptyline
"I had Irritable Bowel Syndrome-Diarrhea for around 8 years. After GP tried everything, as a last resort I was prescribed 5mg before bed. The very next morning I was amazed at the difference. It also helped greatly with sleep. After 3 days I took it every other day, then after another week every 2-3 days, and so on. After 6 weeks I didn't need to take it continuously anymore. Only the occasional times when it flared up during the next year or so. 18 months later I was free of the problems and had to dispose of the remaining prescription! It's very underrated from what I have read."