Effexor or Zoloft?

I was recently switched from effexor to zoloft, can anyone tell me what the difference between the two? I didnt really experience any depression before, but now that I have stopped the effexor and started the zoloft, I do feel alittle down. I have been taking xanax until the zoloft gets in my system.I suffer from panic attacks. The docotor did tell me, that we may have to change the dosage until we find the right amount. I appreciate any suggestions.

[Paxiled]

Zoloft is an ssri, which targets serotonin receptors.  Effexor is an snri, which targets both serotonin and norepinephrine receptors.  Theoretically, this makes Effexor a more specific targeter of depression, but it's also a very difficult drug to take and come off of.  But as to which med will help you the most, that's very individual, and nobody can predict that.  A lot depends on how well you metabolize any particular medication.  As to feeling down, that's part of the withdrawal from Effexor, and could happen quitting any one of these.  You've removed something that's been affecting your brain in a certain way, and now it's no longer doing that so your brain is re-adapting to functioning on its own.  When the Zoloft kicks in, you'll be back to a brain on medication, but it won't target norepinephrine.  Since you don't seem to be being treated for depression, it was probably not the best drug for you anyway.  Zoloft would have been a better first choice.