Go to Google, type in "effexor withdrawal", read stories for 30 minutes...you'll never put another one in your body for sure!
Effexor is one of THE most difficult antidepressants to withdraw from; the nightmare stories & horrible side effects are simply astounding :(
While I'm no specialist or medical professional on anxiety and panic, I know of several people personally (and hundreds that I've read about), that have managed to handle it without addictive/toxic pharmaceutical meds.