I had been on Prozac 22 years with a few relapses of Panic and Anxiety, went 7 years panic free until Mid-April when I had a massive relapse. 11 weeks ago they switched me to Celexa and had no response even after 5 weeks at the max. 40 mg. So they have decided to change me back to Prozac just as I'm about to start teaching next week. A very quick change over 4 days 20 mg celexa and 20 prozac, followed by just prozac for the rest of next week then up fo 40. Terrified of the start up side effects. Have been on klonopin through the summer and to help with the cross over. Need some advice and encouragement.