Hi Toni....I have been on azathioprine now for about 4 scripts.  I started out at 50 mg initially and they have increased it twice so I am taking 150 mg total daily now.  I would say it has irritated my stomach the least of the drugs I've tried.  My problem with it now is that it has depleted my white blood cell count which explains why i've been sick now for going on 4 weeks.  So I am planning on going off of it after I see the doc this coming Thurs as I had labs again today to see what my count is at now.  I can't say that I have really seen much improvement in the pain in my hands since I've taken it.  I was told it is one of the lesser used one and since it didn't upset my stomach the doc said to go ahead and try it.  So I did.  I am going to talk to him about Methotrexate next.  Good luck!!!