HH, I think they are basically the same medication. As I understand it, imuran metabolizes into 6mp in your system. I have seen a few posts here from people who experienced some side effects from one but not from the other, but more often it is a matter of lowering doses. The two main side effects i have seen info on are leuk
openia (suppressiion of white count) and pancreatitis, the first being mroe common than the second, but in only a small percentage of patients. I think the white count problems show up in 10% or so. I have been on 6mp for 5 years now with no problems and good results. The dosage used for Crohn's -- usually 50-75 mg -- is far less than what the drug is used for in other conditions (leukemia for one.) And, there have been several long term studies showing no appreciable cancer increases in 6mp patients. The only thing shown is a very very slight increase in the incidence of lymphoma, but that can also be higher in Crohn's patients in general from long term inflammatory damage.