Interstitial Cystitis
"I was diagnosed with Interstitial Cystitis, had severe baldder pain and pressure for a couple of months. I used OTC meds and even low dose hydromorphone, but it did not help. My doctor prescribed amitriptyline 25mg, however told me to cut it in half and initially use 12.5mg to see if it helps, if not, increase to 25. 

I took the half pill in the evening, and in the morning I woke up with no bladder pain, first time in months. During the day I still had some bladder pressure, but no pain. After 2 weeks on the amitriptyline my pain and pressure are all gone. Have not noticed any side effects, perhaps An occasional constipation, so I started taking fiber."