Is It Advisable To Take Steroids For A Long Time?

I suffered with low platelets count of 20000 during third week of November 2010. And I was given steroid which increased the count to 150000. Bone marrow test revealed production is normal, my physician advised to take steriod 40 mg for two weeks, in between my platelet counts comes down to 50000 , now my physician increase the OMNACARTIL 60 mg for another two weeks. I need your suitable advise, how long I have to be steroid, whether 60 mg Cartil, can I take for too long, please advise.