Here's some more info on immunosuppresants:
IBD is commonly treated with the immunomodulators azathioprine and its metabolite 6-MP.4 The appropriateness of immunosuppressants in the management of IBD was assessed this year using the RAND method.5 The results of this Italian study show that only azathioprine, 6-MP, and methotrexate are appropriate in the treatment of IBD. In addition, cyclosporine A was found to be appropriate only in severe UC after the failure of steroids.
The only drugs able to modify the disease course are azathioprine, 6-MP, and methotrexate.6 However, these drugs have a slow onset of action and are associated with important side effects in some patients, often necessitating the discontinuation of the drug. Moreover, up to 60 percent of patients do not respond to these drugs long-term. Furthermore, serious drug toxicity leads to cessation of therapy in 9 percent to 25 percent of patients, and there is failure to achieve efficacy in approximately 15 percent of cases.7
Data also suggest an approximate fourfold increased risk of lymphoma in IBD patients treated with azathioprine/ 6-MP.4 The increased risk of lymphoma could be a result of the medications, the severity of the underlying disease, or a combination of the two, the researchers concluded.
Nodular regenerative hyperplasia of the liver (NRH) also can develop in IBD patients treated with azathioprine.8 “Clinicians should be aware of this serious complication which may occur with any of the purine analogues (azathioprine, 6-MP, and 6-thioguanine),” according to the researchers who presented four such cases.
http://www.endonurse.com/articles/diseases_disorders/589_5c1feat2.html