I've been on and off imuran (and prednisone) over the past 16 years. I don't recall having my blood tested that frequently. I currently test once a year and I'm on 200mg of imuran. My blood work always shows slight anemia attributed to imuran. Imuran can take 4-6 months or longer for it to 'kick in' so that seems counter to what you're asking.

Infection? If you mean the imuran being the cause of a blood related problem like leukemia then I have no idea. If you mean getting an infection as Annie mentions due to being immunosupressed, then yes, that can happen any time.

Wish I could be more helpful.
Jim