When I was first diagnosed with depression, and it was really severe, I was put on Prozac, and had worked up to 40 mg per day before I stopped taking it. It definitely helped me at that point. I stopped on my own really, just ran out and stopped going to the doctor- but I think I started improving on my own just from there, even if just gradually, having a job helped.
But a few years later when I was thinking of going back to school (I had withdrawn because of the depression), I revisited the doctor, and they put me back on Prozac. I was only on 10mg a day, but it literally drove me nuts- my mind was racing, I was worrying about
everything (which isn't like me at all), and I felt like I was going to have a nervous breakdown. I did find out shortly after I stopped it that I was pregnant- so maybe hormones or something had to do with my reaction, I'm not sure.
But I guess it's probably different for everybody- and as my case might show, different for the same person under different circumstances. Good luck, I hope it helps