[Eternal]

I've moved this over to General Health because I think it fits better here.
When I was on anti-depressants, mine caused my brain to produce more serotonin as I'm low on it. It will take at least 2 weeks before you'll notice a different as Kate said. Keep in mind though that these aren't "happy pills." Instead they typically make your low moods less low. As for which brand to use, your psychiatist/doctor will go over your different options and suggest ones that would work best for you. Prozac tends to be the most commonly prescribed.