Prozac: side effects? a forever drug?

Ritz has been diagnosed with FHS, Feline Hyperesthesia Syndrome.  In Ritz the symptoms are primarily twitching around the flank area, frantic running back and forth, some biting of the flank.  While the cause is unknown, stress is known to exacerbate the symptoms.  In Ritz' case, the symptoms increased significantly after I took her to the vets for a wellness check, she got two shots, and I decreased the amount of food she was eating. 

The vet prescribed Prozac but I am reluctant to start her on that.  BUT:  could Prozac break the cycle could it help her from becoming habituated with the behavior?  Would I have to give it to her for a long time?

Thanks.

I don't know how long you would have to give it, but Prozac is an old SSRI and anti-anxiety drug. I would not give additional serotonin with it though, in humans it ends up being too much of a good thing.