Long ago, before I even found out I had IBS, I asked my psychiatrist to put me on Elavil for my condition. I had my reasons for suspecting that Elavil would help, and sure enough I noticed it helping right away, but I also started out at a much higher dosage (50mg) as recommended by my Psychiatrist. It helped me sleep very well at night, and I woke up in much less pain than the morning after, but eventually it began to cause constipation problems for me so we lowered it to 25mg. But then once I finally saw a GI doctor, he said that 10mg of Elavil was the optimal dosage to treat IBS. Does anyone know why this may be? IIRC, he claimed that IBS (or at least, the pain) was primarily caused by "abnormal" serotonin levels in the gut, and that Elavil would help with that. So why would a lower dosage be better than higher dosage?And can anyone explain to me what it does to my Serotonin levels? I heard that having too low levels of serotonin can be responsible for constipation, and that too high of serotonin levels can cause diarrhea, but I don't suffer from one of those things in particular. My IBS symptoms are primarily just the pain.