Hi Sara,
Had one just recently too, and asked the same question, as the first one I had made no difference. The answer I was given, was to think of the Depomedrone as a sponge and that it can only soak up so much, as in the inflamation. My second and third ones worked really well, although can't remember how quickly. Hope this makes sense, and hope that yours works really quickly for you.
Candy