Prednisone is a steroid drug. I assumed you wanted to stay away from those.
I know you're worried about the 'ballooning' that can happen with steroids, however they are the first line of treatment. Typically other immunosuppressive agents are used either because the disease is so severe that glucocorticoids alone are insufficient treatment, or because the long-term side-effects of these other drugs are less severe than those of glucocorticoids (“steroid-sparing”).
In general, cyclophosphamide is the strongest of the immunosuppressive drugs and is used to treat severe disease that endangers vital organs. Methotrexate, Azathioprine, and other drugs that are used more widely in treating other rheumatic diseases are also used to treat non-life-threatening vasculitis and are useful as steroid-sparing agents - if your doc would go along with that.
There are some new drugs that are developed for treating other autoimmune and inflammatory diseases and these are sometimes subsequently investigated in vasculitis. Plasma exchange (plasmapheresis) and intravenous immunoglobulin (IVIG) have been used (sometimes) in severe cases of particular forms of vasculitis that are thought to be caused by circulating autoantibodies. But it's not a typical thing.