Were you equally reducing the Effexor and replacing it slowly with the Prozac? Maybe your system couldn't handle it which is a shame because you have to suffer miserably to get off the Effexor. I told my doctor getting off of Effexor had to be similar to getting off of heroin. Sorry it didn't work for you. I would take away a 37.5 mg and replace it with 20-40mg of Prozac and it worked so well. I would do that for close to a week and take away another 37.5 but still just used 20-40mg. of Prozac. Then wait close to another week drop another 37.5mg. I remember for a few days towards the end I used 60mg of prozac when I dropped the next 37.5mg of Effexor. It worked like a charm for me.