Prednisone for Hayfever

Hi all,

Every year for the past 2 years I have been prescribed a "Pred Pack" to treat my seasonal allergies as there has been no other remedy that works. Prior to the past 2 years (about 3 years prior) I was given a shot of Prednisone in my hip. This means I have been taking Prednisone for about 5 years. When receiving the Prednisone therapy the results are outstanding and last about a full year (through both spring and fall allergy seasons)

Questions:

Okay, so how can this drug remain effective for so long if it's not in your system the entire time?

How long does it stay in your system? Does anyone know? Would you say I've been on steroid therapy for 5 years? Or, have my doses been spread out enough that you probably wouldn't say that.

I am concerned because I have read that long term use of steroids can be very dangerous and can have very, very negative side affects.

Do you guys think I'm risking it to keep getting these treatments each year?

I think I may be feeling some side effects such as moodiness (I'm also a 40 year old female so could be unrelated)
I've also gained about 40 pounds in the past 5 years going from 120-160. I don't want to be gaining anymore weight!