Just a note to add that it's also really worth it to go to someone who can prescribe these and *also* has some expertise about the different choices, such as a psychiatric nurse-practitioner or a psychiatrist, since the SSRIs all do work differently for different people, as Brain said, but also some tend to generally have more of one kind of side effect than another and it takes someone with some expertise to know about all that.

I took an antidepressant in the past for about a year as I was going through a(another) difficult time in my life. I got the scrip from my general pracitioner doc at the time, it was the most commonly prescribed SSRId at the time (zoloft) and it did get rid of my depression but I also never got rid of a nasty side effect it had which was sometimes severe insomnia, and my GP kept saying to just try it for a little longer and "see if the insomnia goes away...."

Eventually I ended up decising the insomnia was worse than the depression and went off it and found I was doing OK without it. Later a psychiatrist freind of mine told me that someone who knew what they were doing would have prescribed me something else the first time I complained of insomnia.....