This is a well known side effect of SSRI drugs like Zoloft and Prozac. It generally doesn't go away completely. In some cases it can get worse the longer you take it. I dislike pharmaceuticals in general but SSRIs are especially unpredictable. Remember all those murders in the 90's when these drugs became really popular? It was always something like "oh he was such a devoted father and caring husband, then he started taking Prozac and went crazy and shot 4 people dead"...It's just a matter of time before they stop working completely, then you have to deal with withdrawals (look up the brain zaps), and you're right back where you started