Lexapro stopped working

I'm taking an escitalopram since September (20 mg since December) and unfortunately now I have anxiety in the morning and I am quite nervous all day. Of course I still feel much better then before I began to take this drug.

I think that I will switch Lexapro to Prozac (probably 40 - 60 mg). What do you think about this idea?
I read that 40 mg of Prozac is equivalent for 20 mg of Lexapro (which is the highest possible dose due to prolongation of QT interval) and as you know the highest allowed dose of Prozac is 80 mg so it is like 40 mg of Lexapro.

What do you think about it?

You have only been on Lexapro for a few months and already you have decided it is not working (when in fact it is, based on what you wrote). Lexapro is not a valium or klonipin that works immediately. Lexapro works over time. 20mg per day is sufficient. If you feel you need more help, you should add an additional medication, like a benzo, and continue with Lexapro. Changing long-term meds willy nilly will only exacerbate things. Talk to a real psychiatrist and get professional advise on this.