Hi everyone, my fiance was diagnosed with Anca vasulitis in 2014. He started Azathioprine Aug 2015 and is currently still on it and so far doing well..thank God. My question for those of you who are on Azathioprine- how long have you been on it. : is there a limit to how long one can be on this drug? Is Azathioprine known to stop working after a certain amount of years? thank you so much for your reply.