Hi Hannah's mom,
I would encourage you to get another doctor's opinion. The part of your story that's worrying is that the doctor didn't have your daughter try Colazal -- a benign drug- FIRST. To jump to mercaptopurine (6MP) before you try other options makes no sense to me. I'm on 6MP but I spent 10 years on a variety of different drugs that eventually all stopped working for me. When I made the decision with my doctor to try 6MP -- which is not a completely benign drug -- I was confident that it was one of my last options.
Before going on 6MP, I would suggest that someone try EVERY drug in the 5ASA class-- asacol, colazol, dipentum, etc.
At the same time, I would suggest experimenting with different combinations of rectal meds -- rowasa, canasa, and the steroid rectal meds: Coritfoam and Cortenema.
Are you in the U.S. and can you easily get a second opinion from another doctor? It would be worth travelling to a good medical center so that your daughter can get a top-notch opinion about her meds.
By the way, 6MP can take 6 months to work, so being on that along with just 15 mg of prednisone is probably not doing much for her. 15 mg of pred is pretty low and assuming that the 6MP hasn't kicked in yet, then she is in effect barely getting her UC treated. She should try rectal steroid meds to see if she can control the bleeding that way.
So sorry that she's having a tough time. Also sorry if I sound too strong in my opinion; I get annoyed when doctors jump to immunosuppressors and steroids before trying the harmless drugs first.
UC for the last ten years
Current Meds: 6MP since 2006, Cortifoam
Past Meds: You name it; I've tried it. (Asacol, Colazol, Pentasa, DiPentum, Rowasa, Canasa, Cortenema, sulfasalazine)