Imuran is an old med (been around for 30 or 40 years) and has been taken by millions of patients, mostly without problems. Some react to the drug immediately and are taken off and another tried. Others have problems over time and it usually hits the blood which is why you should get tested every 2-3 months with CBC tests....not the one you are getting.
Probably the biggest risk is an increased risk of cancer. Cancer screening that is age and gender appropriate is wise. However, all of the suppression meds carry a higher risk of infection and cancer so you can't get away from that risk entirely no matter what you take. When deciding on any med there is a risk/benefit analysis that should be done....does the benefit of taking the drug outweigh the risk of side effects. That is true with every drug we might take including aspirin.
It is also used as a transplant med. It is very well known and documented unlike newer drugs so it is not that scary. I am still on it after 4 years and will probably be off in the next year. Other than lowering my rbc, wbc and platelets I had no side effects whatsoever. Blood tests caught the problem and my rheumy reduced the dosage and all is well.
MCTD (lupus, scleroderma, polymyositis). Diagnosed 2005. Kidney, liver, GI tract, dysphagia, raynauds, Barretts esophagus, quadriplegic in 2005. Recovered and now active in skiing, tai, chi, hiking, golf. Meds: prednisone 2.5mg, imuran 25mg, amlodipine, benazapril, omeprazole, potassium, folic acid, vitamins, maxide and various supplements and vitamins.
Remain optimistic and you can overcome the odds.