Tramadol
"I take it for gastrointestinal pain and it works fairly well. My pain often gets to the point of me wanting to punch everything in sight, and tramadol helps to quiet it. The only downsides are that it takes a little longer to start working than I need it to, since this unbearable pain can arise in a few minutes. Additionally, it causes constipation even in low doses, which can contribute to further gastrointestinal pain."