Following a deadly allergic reaction to Celebrex, I was given an injection of prednizone, and prescribed 60 mgs. of Prednizone per day for a week. By the third day, my anxiety and what they call "steroid psychosis" was so bad I thought I was going mad. I suffered horrible insomnia, crying attacks, paranoia, fear...you name it. On the fourth day, my knee swelled up horribly and walking was nearly impossible. I stopped taking Prednizone cold turkey on the fourth day (which you are NOT supposed to do, but my doctor didn't tell me that). It has been over 6 weeks since the episode and I am still suffering knee and joint pain, gained 26 pounds and have a red face and horrible acne. My knee has a horrific bulge still. I had an MRI on the knee, and they say that I have fluid buildup on the joint. I have no idea how long it will take to get this drug out of my system, but I would caution anyone to seriously reconsider taking it unless it is life threatening. I believe my allergic reaction could have been treated with just benadryl alone.