I'm no expert, have only had aza... Both are immune supressant meds so arguably do the same thing... Maybe adjusting the dose rather than the drug is the better idea in the first instance? It recommends 2mg for every kg of body weight... So I was on 125mg, if I was sick my doc just advised I up to 150mg... But went down to 75 when in remission to ease side effects...
Chat with the doc or specialist nurse, you might need a change or a dose of roids to control it again
Let us know how you get on!
xxx