On Imuran's behalf, I believe it has been a stabilizing force in my MS adventure. I'm am very med sensitive and this one has no side effects that I've noticed. I took it for about 3 years, stopped because I moved across country. New neuro said no Imuran. Had me try another DMD and I didn't tolerate that one either. That was 3 strikes, no Av, Cop, or Rbf.
Finally he relented after a year of continuous exacerbations and no other treatments. I've been back on it and re-stabilized for 1-1/2 years and counting. I'm now back in my home state, with my old doc and happily taking Imuran.
When used at a high dose as chemotherapy the side effects are intense, I would think. I take one 50mg tab 3x day. At such a low dose it reduces the immune system made overactive by MS. Like I said, years without any issues.
Trust yourself and take your time making decisions. I wish you all the best.